[pkg] unify client and server into a single python package

We have been discussing about this merge for a while.
Its main goal is to simplify things: code navigation, but also
packaging.

The rationale is that the code is more cohesive in this way, and there's
only one source package to install.

Dependencies that are only for the server or the client will not be
installed by default, and they are expected to be provided by the
environment. There are setuptools extras defined for the client and the
server.

Debianization is still expected to split the single source package into
3 binaries.

Another avantage is that the documentation can now install a single
package with a single step, and therefore include the docstrings into
the generated docs.

- Resolves: #8896

43 files changed, 8262 insertions, 0 deletions

diff --git a/src/leap/soledad/client/__init__.py b/src/leap/soledad/client/__init__.py
new file mode 100644
index 00000000..bcad78db
--- /dev/null
+++ b/src/leap/soledad/client/__init__.py
@@ -0,0 +1,30 @@
+# -*- coding: utf-8 -*-
+# __init__.py
+# Copyright (C) 2013, 2014 LEAP
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+"""
+Soledad - Synchronization Of Locally Encrypted Data Among Devices.
+"""
+from leap.soledad.common import soledad_assert
+
+from .api import Soledad
+from ._document import Document, AttachmentStates
+from ._version import get_versions
+
+__version__ = get_versions()['version']
+del get_versions
+
+__all__ = ['soledad_assert', 'Soledad', 'Document', 'AttachmentStates',
+           '__version__']
diff --git a/src/leap/soledad/client/_crypto.py b/src/leap/soledad/client/_crypto.py
new file mode 100644
index 00000000..8cedf52e
--- /dev/null
+++ b/src/leap/soledad/client/_crypto.py
@@ -0,0 +1,557 @@
+# -*- coding: utf-8 -*-
+# _crypto.py
+# Copyright (C) 2016 LEAP Encryption Access Project
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+"""
+Cryptographic operations for the soledad client.
+
+This module implements streaming crypto operations.
+It replaces the old client.crypto module, that will be deprecated in soledad
+0.12.
+
+The algorithm for encrypting and decrypting is as follow:
+
+The KEY is a 32 bytes value.
+The IV is a random 16 bytes value.
+The PREAMBLE is a packed_structure with encryption metadata, such as IV.
+The SEPARATOR is a space.
+
+Encryption
+----------
+
+IV = os.urandom(16)
+PREAMBLE = BLOB_SIGNATURE_MAGIC, ENC_SCHEME, ENC_METHOD, time, IV, doc_id, rev,
+and size.
+
+PREAMBLE = base64_encoded(PREAMBLE)
+CIPHERTEXT = base64_encoded(AES_GCM(KEY, cleartext) + resulting_tag) if armor
+
+CIPHERTEXT = AES_GCM(KEY, cleartext) + resulting_tag if not armor
+# "resulting_tag" came from AES-GCM encryption. It will be the last 16 bytes of
+# our ciphertext.
+
+encrypted_payload = PREAMBLE + SEPARATOR + CIPHERTEXT
+
+Decryption
+----------
+
+Ciphertext and Tag CAN come encoded in base64 (with armor=True) or raw (with
+armor=False). Preamble will always come encoded in base64.
+
+PREAMBLE, CIPHERTEXT = PAYLOAD.SPLIT(' ', 1)
+
+PREAMBLE = base64_decode(PREAMBLE)
+CIPHERTEXT = base64_decode(CIPHERTEXT) if armor else CIPHERTEXT
+
+CIPHERTEXT, TAG = CIPHERTEXT[:-16], CIPHERTEXT[-16:]
+CLEARTEXT = aes_gcm_decrypt(KEY, IV, CIPHERTEXT, TAG, associated_data=PREAMBLE)
+
+AES-GCM will check preamble authenticity as well, since we are using
+Authenticated Encryption with Associated Data (AEAD). Ciphertext and associated
+data (PREAMBLE) authenticity will both be checked together during decryption.
+PREAMBLE consistency (if it matches the desired document, for instance) is
+checked during PREAMBLE reading.
+"""
+
+
+import base64
+import hashlib
+import warnings
+import hmac
+import os
+import struct
+import time
+
+from io import BytesIO
+from collections import namedtuple
+
+from twisted.internet import defer
+from twisted.internet import interfaces
+from twisted.web.client import FileBodyProducer
+
+from leap.soledad.common import soledad_assert
+from cryptography.exceptions import InvalidTag
+from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
+from cryptography.hazmat.backends import default_backend
+
+from zope.interface import implementer
+
+
+SECRET_LENGTH = 64
+SEPARATOR = ' '  # Anything that doesn't belong to base64 encoding
+
+CRYPTO_BACKEND = default_backend()
+
+PACMAN = struct.Struct('2sbbQ16s255p255pQ')
+LEGACY_PACMAN = struct.Struct('2sbbQ16s255p255p')
+BLOB_SIGNATURE_MAGIC = '\x13\x37'
+
+
+ENC_SCHEME = namedtuple('SCHEME', 'symkey')(1)
+ENC_METHOD = namedtuple('METHOD', 'aes_256_ctr aes_256_gcm')(1, 2)
+DocInfo = namedtuple('DocInfo', 'doc_id rev')
+
+
+class EncryptionDecryptionError(Exception):
+    pass
+
+
+class InvalidBlob(Exception):
+    pass
+
+
+class SoledadCrypto(object):
+    """
+    This class provides convenient methods for document encryption and
+    decryption using BlobEncryptor and BlobDecryptor classes.
+    """
+    def __init__(self, secret):
+        """
+        Initialize the crypto object.
+
+        :param secret: The Soledad remote storage secret.
+        :type secret: str
+        """
+        self.secret = secret
+
+    def encrypt_doc(self, doc):
+        """
+        Creates and configures a BlobEncryptor, asking it to start encryption
+        and wrapping the result as a simple JSON string with a "raw" key.
+
+        :param doc: the document to be encrypted.
+        :type doc: Document
+        :return: A deferred whose callback will be invoked with a JSON string
+            containing the ciphertext as the value of "raw" key.
+        :rtype: twisted.internet.defer.Deferred
+        """
+
+        def put_raw(blob):
+            raw = blob.getvalue()
+            return '{"raw": "' + raw + '"}'
+
+        content = BytesIO(str(doc.get_json()))
+        info = DocInfo(doc.doc_id, doc.rev)
+        del doc
+        encryptor = BlobEncryptor(info, content, secret=self.secret)
+        d = encryptor.encrypt()
+        d.addCallback(put_raw)
+        return d
+
+    def decrypt_doc(self, doc):
+        """
+        Creates and configures a BlobDecryptor, asking it decrypt and returning
+        the decrypted cleartext content from the encrypted document.
+
+        :param doc: the document to be decrypted.
+        :type doc: Document
+        :return: The decrypted cleartext content of the document.
+        :rtype: str
+        """
+        info = DocInfo(doc.doc_id, doc.rev)
+        ciphertext = BytesIO()
+        payload = doc.content['raw']
+        del doc
+        ciphertext.write(str(payload))
+        decryptor = BlobDecryptor(info, ciphertext, secret=self.secret)
+        return decryptor.decrypt()
+
+
+def encrypt_sym(data, key, method=ENC_METHOD.aes_256_gcm):
+    """
+    Encrypt data using AES-256 cipher in selected mode.
+
+    :param data: The data to be encrypted.
+    :type data: str
+    :param key: The key used to encrypt data (must be 256 bits long).
+    :type key: str
+
+    :return: A tuple with the initialization vector and the ciphertext, both
+        encoded as base64.
+    :rtype: (str, str)
+    """
+    mode = _mode_by_method(method)
+    encryptor = AESWriter(key, mode=mode)
+    encryptor.write(data)
+    _, ciphertext = encryptor.end()
+    iv = base64.b64encode(encryptor.iv)
+    tag = encryptor.tag or ''
+    return iv, ciphertext + tag
+
+
+def decrypt_sym(data, key, iv, method=ENC_METHOD.aes_256_gcm):
+    """
+    Decrypt data using AES-256 cipher in selected mode.
+
+    :param data: The data to be decrypted.
+    :type data: str
+    :param key: The symmetric key used to decrypt data (must be 256 bits
+                long).
+    :type key: str
+    :param iv: The base64 encoded initialization vector.
+    :type iv: str
+
+    :return: The decrypted data.
+    :rtype: str
+    """
+    _iv = base64.b64decode(str(iv))
+    mode = _mode_by_method(method)
+    tag = None
+    if mode == modes.GCM:
+        data, tag = data[:-16], data[-16:]
+    decryptor = AESWriter(key, _iv, tag=tag, mode=mode)
+    decryptor.write(data)
+    _, plaintext = decryptor.end()
+    return plaintext
+
+
+# TODO maybe rename this to Encryptor, since it will be used by blobs an non
+# blobs in soledad.
+class BlobEncryptor(object):
+    """
+    Produces encrypted data from the cleartext data associated with a given
+    Document using AES-256 cipher in GCM mode.
+
+    The production happens using a Twisted's FileBodyProducer, which uses a
+    Cooperator to schedule calls and can be paused/resumed. Each call takes at
+    most 65536 bytes from the input.
+
+    Both the production input and output are file descriptors, so they can be
+    applied to a stream of data.
+    """
+    # TODO
+    # This class needs further work to allow for proper streaming.
+    # Right now we HAVE TO WAIT until the end of the stream before encoding the
+    # result. It should be possible to do that just encoding the chunks and
+    # passing them to a sink, but for that we have to encode the chunks at
+    # proper alignment (3 bytes?) with b64 if armor is defined.
+
+    def __init__(self, doc_info, content_fd, secret=None, armor=True,
+                 sink=None):
+        if not secret:
+            raise EncryptionDecryptionError('no secret given')
+
+        self.doc_id = doc_info.doc_id
+        self.rev = doc_info.rev
+        self.armor = armor
+
+        self._content_fd = content_fd
+        self._content_size = self._get_rounded_size(content_fd)
+        self._producer = FileBodyProducer(content_fd, readSize=2**16)
+
+        self.sym_key = _get_sym_key_for_doc(doc_info.doc_id, secret)
+        self._aes = AESWriter(self.sym_key, _buffer=sink)
+        self._aes.authenticate(self._encode_preamble())
+
+    def _get_rounded_size(self, fd):
+        """
+        Returns a rounded value in order to minimize information leaks due to
+        the original size being exposed.
+        """
+        fd.seek(0, os.SEEK_END)
+        size = _ceiling(fd.tell())
+        fd.seek(0)
+        return size
+
+    @property
+    def iv(self):
+        return self._aes.iv
+
+    @property
+    def tag(self):
+        return self._aes.tag
+
+    def encrypt(self):
+        """
+        Starts producing encrypted data from the cleartext data.
+
+        :return: A deferred which will be fired when encryption ends and whose
+                 callback will be invoked with the resulting ciphertext.
+        :rtype: twisted.internet.defer.Deferred
+        """
+        # XXX pass a sink to aes?
+        d = self._producer.startProducing(self._aes)
+        d.addCallback(lambda _: self._end_crypto_stream_and_encode_result())
+        return d
+
+    def _encode_preamble(self):
+        current_time = int(time.time())
+
+        preamble = PACMAN.pack(
+            BLOB_SIGNATURE_MAGIC,
+            ENC_SCHEME.symkey,
+            ENC_METHOD.aes_256_gcm,
+            current_time,
+            self.iv,
+            str(self.doc_id),
+            str(self.rev),
+            self._content_size)
+        return preamble
+
+    def _end_crypto_stream_and_encode_result(self):
+
+        # TODO ---- this needs to be refactored to allow PROPER streaming
+        # We should write the preamble as soon as possible,
+        # Is it possible to write the AES stream as soon as it is encrypted by
+        # chunks?
+        # FIXME also, it needs to be able to encode chunks with base64 if armor
+
+        preamble, encrypted = self._aes.end()
+        result = BytesIO()
+        result.write(
+            base64.urlsafe_b64encode(preamble))
+        result.write(SEPARATOR)
+
+        if self.armor:
+            result.write(
+                base64.urlsafe_b64encode(encrypted + self.tag))
+        else:
+            result.write(encrypted + self.tag)
+
+        result.seek(0)
+        return defer.succeed(result)
+
+
+# TODO maybe rename this to just Decryptor, since it will be used by blobs
+# and non blobs in soledad.
+class BlobDecryptor(object):
+    """
+    Decrypts an encrypted blob associated with a given Document.
+
+    Will raise an exception if the blob doesn't have the expected structure, or
+    if the GCM tag doesn't verify.
+    """
+    def __init__(self, doc_info, ciphertext_fd, result=None,
+                 secret=None, armor=True, start_stream=True, tag=None):
+        if not secret:
+            raise EncryptionDecryptionError('no secret given')
+
+        self.doc_id = doc_info.doc_id
+        self.rev = doc_info.rev
+        self.fd = ciphertext_fd
+        self.armor = armor
+        self._producer = None
+        self.result = result or BytesIO()
+        sym_key = _get_sym_key_for_doc(doc_info.doc_id, secret)
+        self.size = None
+        self.tag = None
+
+        preamble, iv = self._consume_preamble()
+        soledad_assert(preamble)
+        soledad_assert(iv)
+
+        self._aes = AESWriter(sym_key, iv, self.result, tag=tag or self.tag)
+        self._aes.authenticate(preamble)
+        if start_stream:
+            self._start_stream()
+
+    @property
+    def decrypted_content_size(self):
+        return self._aes.written
+
+    def _start_stream(self):
+        self._producer = FileBodyProducer(self.fd, readSize=2**16)
+
+    def _consume_preamble(self):
+        """
+        Consume the preamble and write remaining bytes as ciphertext. This
+        function is called during a stream and can be holding both, so we need
+        to consume only preamble and store the remaining.
+        """
+        self.fd.seek(0)
+        try:
+            parts = self.fd.getvalue().split(SEPARATOR, 1)
+            preamble = base64.urlsafe_b64decode(parts[0])
+            if len(parts) == 2:
+                ciphertext = parts[1]
+                if self.armor:
+                    ciphertext = base64.urlsafe_b64decode(ciphertext)
+                self.tag, ciphertext = ciphertext[-16:], ciphertext[:-16]
+                self.fd.seek(0)
+                self.fd.write(ciphertext)
+                self.fd.seek(len(ciphertext))
+                self.fd.truncate()
+                self.fd.seek(0)
+
+        except (TypeError, ValueError):
+            raise InvalidBlob
+
+        try:
+            if len(preamble) == LEGACY_PACMAN.size:
+                warnings.warn("Decrypting a legacy document without size. " +
+                              "This will be deprecated in 0.12. Doc was: " +
+                              "doc_id: %s rev: %s" % (self.doc_id, self.rev),
+                              Warning)
+                unpacked_data = LEGACY_PACMAN.unpack(preamble)
+                magic, sch, meth, ts, iv, doc_id, rev = unpacked_data
+            elif len(preamble) == PACMAN.size:
+                unpacked_data = PACMAN.unpack(preamble)
+                magic, sch, meth, ts, iv, doc_id, rev, doc_size = unpacked_data
+                self.size = doc_size
+            else:
+                raise InvalidBlob("Unexpected preamble size %d", len(preamble))
+        except struct.error as e:
+            raise InvalidBlob(e)
+
+        if magic != BLOB_SIGNATURE_MAGIC:
+            raise InvalidBlob
+        # TODO check timestamp. Just as a sanity check, but for instance
+        # we can refuse to process something that is in the future or
+        # too far in the past (1984 would be nice, hehe)
+        if sch != ENC_SCHEME.symkey:
+            raise InvalidBlob('Invalid scheme: %s' % sch)
+        if meth != ENC_METHOD.aes_256_gcm:
+            raise InvalidBlob('Invalid encryption scheme: %s' % meth)
+        if rev != self.rev:
+            msg = 'Invalid revision. Expected: %s, was: %s' % (self.rev, rev)
+            raise InvalidBlob(msg)
+        if doc_id != self.doc_id:
+            msg = 'Invalid doc_id. '
+            + 'Expected: %s, was: %s' % (self.doc_id, doc_id)
+            raise InvalidBlob(msg)
+
+        return preamble, iv
+
+    def _end_stream(self):
+        try:
+            self._aes.end()
+        except InvalidTag:
+            raise InvalidBlob('Invalid Tag. Blob authentication failed.')
+        fd = self.result
+        fd.seek(0)
+        return self.result
+
+    def decrypt(self):
+        """
+        Starts producing encrypted data from the cleartext data.
+
+        :return: A deferred which will be fired when encryption ends and whose
+            callback will be invoked with the resulting ciphertext.
+        :rtype: twisted.internet.defer.Deferred
+        """
+        d = self.startProducing()
+        d.addCallback(lambda _: self._end_stream())
+        return d
+
+    def startProducing(self):
+        if not self._producer:
+            self._start_stream()
+        return self._producer.startProducing(self._aes)
+
+    def endStream(self):
+        self._end_stream()
+
+    def write(self, data):
+        self._aes.write(data)
+
+    def close(self):
+        result = self._aes.end()
+        return result
+
+
+@implementer(interfaces.IConsumer)
+class AESWriter(object):
+    """
+    A Twisted's Consumer implementation that takes an input file descriptor and
+    applies AES-256 cipher in GCM mode.
+
+    It is used both for encryption and decryption of a stream, depending of the
+    value of the tag parameter. If you pass a tag, it will operate in
+    decryption mode, verifying the authenticity of the preamble and ciphertext.
+    If no tag is passed, encryption mode is assumed, which will generate a tag.
+    """
+
+    def __init__(self, key, iv=None, _buffer=None, tag=None, mode=modes.GCM):
+        if len(key) != 32:
+            raise EncryptionDecryptionError('key is not 256 bits')
+
+        if tag is not None:
+            # if tag, we're decrypting
+            assert iv is not None
+
+        self.iv = iv or os.urandom(16)
+        self.buffer = _buffer or BytesIO()
+        cipher = _get_aes_cipher(key, self.iv, tag, mode)
+        cipher = cipher.decryptor() if tag else cipher.encryptor()
+        self.cipher, self.aead = cipher, ''
+        self.written = 0
+
+    def authenticate(self, data):
+        self.aead += data
+        self.cipher.authenticate_additional_data(data)
+
+    @property
+    def tag(self):
+        return getattr(self.cipher, 'tag', None)
+
+    def write(self, data):
+        self.written += len(data)
+        self.buffer.write(self.cipher.update(data))
+
+    def end(self):
+        self.buffer.write(self.cipher.finalize())
+        return self.aead, self.buffer.getvalue()
+
+
+def is_symmetrically_encrypted(content):
+    """
+    Returns True if the document was symmetrically encrypted.
+    'EzcB' is the base64 encoding of \x13\x37 magic number and 1 (symmetrically
+    encrypted value for enc_scheme flag).
+
+    :param doc: The document content as string
+    :type doc: str
+
+    :rtype: bool
+    """
+    sym_signature = '{"raw": "EzcB'
+    return content and content.startswith(sym_signature)
+
+
+# utils
+
+
+def _hmac_sha256(key, data):
+    return hmac.new(key, data, hashlib.sha256).digest()
+
+
+def _get_sym_key_for_doc(doc_id, secret):
+    key = secret[SECRET_LENGTH:]
+    return _hmac_sha256(key, doc_id)
+
+
+def _get_aes_cipher(key, iv, tag, mode=modes.GCM):
+    mode = mode(iv, tag) if mode == modes.GCM else mode(iv)
+    return Cipher(algorithms.AES(key), mode, backend=CRYPTO_BACKEND)
+
+
+def _mode_by_method(method):
+    if method == ENC_METHOD.aes_256_gcm:
+        return modes.GCM
+    else:
+        return modes.CTR
+
+
+def _ceiling(size):
+    """
+    Some simplistic ceiling scheme that uses powers of 2.
+    We report everything below 4096 bytes as that minimum threshold.
+    See #8759 for research pending for less simplistic/aggresive strategies.
+    """
+    for i in xrange(12, 31):
+        step = 2 ** i
+        if size < step:
+            return step
diff --git a/src/leap/soledad/client/_db/__init__.py b/src/leap/soledad/client/_db/__init__.py
new file mode 100644
index 00000000..e69de29b
--- /dev/null
+++ b/src/leap/soledad/client/_db/__init__.py
diff --git a/src/leap/soledad/client/_db/adbapi.py b/src/leap/soledad/client/_db/adbapi.py
new file mode 100644
index 00000000..5c28d108
--- /dev/null
+++ b/src/leap/soledad/client/_db/adbapi.py
@@ -0,0 +1,298 @@
+# -*- coding: utf-8 -*-
+# adbapi.py
+# Copyright (C) 2013, 2014 LEAP
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+"""
+An asyncrhonous interface to soledad using sqlcipher backend.
+It uses twisted.enterprise.adbapi.
+"""
+import re
+import sys
+
+from functools import partial
+
+from twisted.enterprise import adbapi
+from twisted.internet.defer import DeferredSemaphore
+from twisted.python import compat
+from zope.proxy import ProxyBase, setProxiedObject
+
+from leap.soledad.common.log import getLogger
+from leap.soledad.common.errors import DatabaseAccessError
+
+from . import sqlcipher
+from . import pragmas
+
+if sys.version_info[0] < 3:
+    from pysqlcipher import dbapi2
+else:
+    from pysqlcipher3 import dbapi2
+
+
+logger = getLogger(__name__)
+
+
+"""
+How long the SQLCipher connection should wait for the lock to go away until
+raising an exception.
+"""
+SQLCIPHER_CONNECTION_TIMEOUT = 10
+
+"""
+How many times a SQLCipher query should be retried in case of timeout.
+"""
+SQLCIPHER_MAX_RETRIES = 20
+
+
+def getConnectionPool(opts, openfun=None, driver="pysqlcipher"):
+    """
+    Return a connection pool.
+
+    :param opts:
+        Options for the SQLCipher connection.
+    :type opts: SQLCipherOptions
+    :param openfun:
+        Callback invoked after every connect() on the underlying DB-API
+        object.
+    :type openfun: callable
+    :param driver:
+        The connection driver.
+    :type driver: str
+
+    :return: A U1DB connection pool.
+    :rtype: U1DBConnectionPool
+    """
+    if openfun is None and driver == "pysqlcipher":
+        openfun = partial(pragmas.set_init_pragmas, opts=opts)
+    return U1DBConnectionPool(
+        opts,
+        # the following params are relayed "as is" to twisted's
+        # ConnectionPool.
+        "%s.dbapi2" % driver, opts.path, timeout=SQLCIPHER_CONNECTION_TIMEOUT,
+        check_same_thread=False, cp_openfun=openfun)
+
+
+class U1DBConnection(adbapi.Connection):
+    """
+    A wrapper for a U1DB connection instance.
+    """
+
+    u1db_wrapper = sqlcipher.SoledadSQLCipherWrapper
+    """
+    The U1DB wrapper to use.
+    """
+
+    def __init__(self, pool, init_u1db=False):
+        """
+        :param pool: The pool of connections to that owns this connection.
+        :type pool: adbapi.ConnectionPool
+        :param init_u1db: Wether the u1db database should be initialized.
+        :type init_u1db: bool
+        """
+        self.init_u1db = init_u1db
+        try:
+            adbapi.Connection.__init__(self, pool)
+        except dbapi2.DatabaseError as e:
+            raise DatabaseAccessError(
+                'Error initializing connection to sqlcipher database: %s'
+                % str(e))
+
+    def reconnect(self):
+        """
+        Reconnect to the U1DB database.
+        """
+        if self._connection is not None:
+            self._pool.disconnect(self._connection)
+        self._connection = self._pool.connect()
+
+        if self.init_u1db:
+            self._u1db = self.u1db_wrapper(
+                self._connection,
+                self._pool.opts)
+
+    def __getattr__(self, name):
+        """
+        Route the requested attribute either to the U1DB wrapper or to the
+        connection.
+
+        :param name: The name of the attribute.
+        :type name: str
+        """
+        if name.startswith('u1db_'):
+            attr = re.sub('^u1db_', '', name)
+            return getattr(self._u1db, attr)
+        else:
+            return getattr(self._connection, name)
+
+
+class U1DBTransaction(adbapi.Transaction):
+    """
+    A wrapper for a U1DB 'cursor' object.
+    """
+
+    def __getattr__(self, name):
+        """
+        Route the requested attribute either to the U1DB wrapper of the
+        connection or to the actual connection cursor.
+
+        :param name: The name of the attribute.
+        :type name: str
+        """
+        if name.startswith('u1db_'):
+            attr = re.sub('^u1db_', '', name)
+            return getattr(self._connection._u1db, attr)
+        else:
+            return getattr(self._cursor, name)
+
+
+class U1DBConnectionPool(adbapi.ConnectionPool):
+    """
+    Represent a pool of connections to an U1DB database.
+    """
+
+    connectionFactory = U1DBConnection
+    transactionFactory = U1DBTransaction
+
+    def __init__(self, opts, *args, **kwargs):
+        """
+        Initialize the connection pool.
+        """
+        self.opts = opts
+        try:
+            adbapi.ConnectionPool.__init__(self, *args, **kwargs)
+        except dbapi2.DatabaseError as e:
+            raise DatabaseAccessError(
+                'Error initializing u1db connection pool: %s' % str(e))
+
+        # all u1db connections, hashed by thread-id
+        self._u1dbconnections = {}
+
+        # The replica uid, primed by the connections on init.
+        self.replica_uid = ProxyBase(None)
+
+        try:
+            conn = self.connectionFactory(
+                self, init_u1db=True)
+            replica_uid = conn._u1db._real_replica_uid
+            setProxiedObject(self.replica_uid, replica_uid)
+        except DatabaseAccessError as e:
+            self.threadpool.stop()
+            raise DatabaseAccessError(
+                "Error initializing connection factory: %s" % str(e))
+
+    def runU1DBQuery(self, meth, *args, **kw):
+        """
+        Execute a U1DB query in a thread, using a pooled connection.
+
+        Concurrent threads trying to update the same database may timeout
+        because of other threads holding the database lock. Because of this,
+        we will retry SQLCIPHER_MAX_RETRIES times and fail after that.
+
+        :param meth: The U1DB wrapper method name.
+        :type meth: str
+
+        :return: a Deferred which will fire the return value of
+            'self._runU1DBQuery(Transaction(...), *args, **kw)', or a Failure.
+        :rtype: twisted.internet.defer.Deferred
+        """
+        meth = "u1db_%s" % meth
+        semaphore = DeferredSemaphore(SQLCIPHER_MAX_RETRIES)
+
+        def _run_interaction():
+            return self.runInteraction(
+                self._runU1DBQuery, meth, *args, **kw)
+
+        def _errback(failure):
+            failure.trap(dbapi2.OperationalError)
+            if failure.getErrorMessage() == "database is locked":
+                logger.warn("database operation timed out")
+                should_retry = semaphore.acquire()
+                if should_retry:
+                    logger.warn("trying again...")
+                    return _run_interaction()
+                logger.warn("giving up!")
+            return failure
+
+        d = _run_interaction()
+        d.addErrback(_errback)
+        return d
+
+    def _runU1DBQuery(self, trans, meth, *args, **kw):
+        """
+        Execute a U1DB query.
+
+        :param trans: An U1DB transaction.
+        :type trans: adbapi.Transaction
+        :param meth: the U1DB wrapper method name.
+        :type meth: str
+        """
+        meth = getattr(trans, meth)
+        return meth(*args, **kw)
+        # XXX should return a fetchall?
+
+    # XXX add _runOperation too
+
+    def _runInteraction(self, interaction, *args, **kw):
+        """
+        Interact with the database and return the result.
+
+        :param interaction:
+            A callable object whose first argument is an
+            L{adbapi.Transaction}.
+        :type interaction: callable
+        :return: a Deferred which will fire the return value of
+            'interaction(Transaction(...), *args, **kw)', or a Failure.
+        :rtype: twisted.internet.defer.Deferred
+        """
+        tid = self.threadID()
+        u1db = self._u1dbconnections.get(tid)
+        conn = self.connectionFactory(
+            self, init_u1db=not bool(u1db))
+
+        if self.replica_uid is None:
+            replica_uid = conn._u1db._real_replica_uid
+            setProxiedObject(self.replica_uid, replica_uid)
+
+        if u1db is None:
+            self._u1dbconnections[tid] = conn._u1db
+        else:
+            conn._u1db = u1db
+
+        trans = self.transactionFactory(self, conn)
+        try:
+            result = interaction(trans, *args, **kw)
+            trans.close()
+            conn.commit()
+            return result
+        except:
+            excType, excValue, excTraceback = sys.exc_info()
+            try:
+                conn.rollback()
+            except:
+                logger.error(None, "Rollback failed")
+            compat.reraise(excValue, excTraceback)
+
+    def finalClose(self):
+        """
+        A final close, only called by the shutdown trigger.
+        """
+        self.shutdownID = None
+        if self.threadpool.started:
+            self.threadpool.stop()
+        self.running = False
+        for conn in self.connections.values():
+            self._close(conn)
+        for u1db in self._u1dbconnections.values():
+            self._close(u1db)
+        self.connections.clear()
diff --git a/src/leap/soledad/client/_db/blobs.py b/src/leap/soledad/client/_db/blobs.py
new file mode 100644
index 00000000..10b90c71
--- /dev/null
+++ b/src/leap/soledad/client/_db/blobs.py
@@ -0,0 +1,554 @@
+# -*- coding: utf-8 -*-
+# _blobs.py
+# Copyright (C) 2017 LEAP
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+"""
+Clientside BlobBackend Storage.
+"""
+
+from urlparse import urljoin
+
+import binascii
+import os
+import base64
+
+from io import BytesIO
+from functools import partial
+
+from twisted.logger import Logger
+from twisted.enterprise import adbapi
+from twisted.internet import defer
+from twisted.web.client import FileBodyProducer
+
+import treq
+
+from leap.soledad.common.errors import SoledadError
+from leap.common.files import mkdir_p
+
+from .._document import BlobDoc
+from .._crypto import DocInfo
+from .._crypto import BlobEncryptor
+from .._crypto import BlobDecryptor
+from .._http import HTTPClient
+from .._pipes import TruncatedTailPipe
+from .._pipes import PreamblePipe
+
+from . import pragmas
+from . import sqlcipher
+
+
+logger = Logger()
+FIXED_REV = 'ImmutableRevision'  # Blob content is immutable
+
+
+class BlobAlreadyExistsError(SoledadError):
+    pass
+
+
+class ConnectionPool(adbapi.ConnectionPool):
+
+    def insertAndGetLastRowid(self, *args, **kwargs):
+        """
+        Execute an SQL query and return the last rowid.
+
+        See: https://sqlite.org/c3ref/last_insert_rowid.html
+        """
+        return self.runInteraction(
+            self._insertAndGetLastRowid, *args, **kwargs)
+
+    def _insertAndGetLastRowid(self, trans, *args, **kw):
+        trans.execute(*args, **kw)
+        return trans.lastrowid
+
+    def blob(self, table, column, irow, flags):
+        """
+        Open a BLOB for incremental I/O.
+
+        Return a handle to the BLOB that would be selected by:
+
+          SELECT column FROM table WHERE rowid = irow;
+
+        See: https://sqlite.org/c3ref/blob_open.html
+
+        :param table: The table in which to lookup the blob.
+        :type table: str
+        :param column: The column where the BLOB is located.
+        :type column: str
+        :param rowid: The rowid of the BLOB.
+        :type rowid: int
+        :param flags: If zero, BLOB is opened for read-only. If non-zero,
+                      BLOB is opened for RW.
+        :type flags: int
+
+        :return: A BLOB handle.
+        :rtype: pysqlcipher.dbapi.Blob
+        """
+        return self.runInteraction(self._blob, table, column, irow, flags)
+
+    def _blob(self, trans, table, column, irow, flags):
+        # TODO: should not use transaction private variable here
+        handle = trans._connection.blob(table, column, irow, flags)
+        return handle
+
+
+def check_http_status(code):
+    if code == 409:
+        raise BlobAlreadyExistsError()
+    elif code != 200:
+        raise SoledadError("Server Error")
+
+
+class DecrypterBuffer(object):
+
+    def __init__(self, blob_id, secret, tag):
+        self.doc_info = DocInfo(blob_id, FIXED_REV)
+        self.secret = secret
+        self.tag = tag
+        self.preamble_pipe = PreamblePipe(self._make_decryptor)
+
+    def _make_decryptor(self, preamble):
+        self.decrypter = BlobDecryptor(
+            self.doc_info, preamble,
+            secret=self.secret,
+            armor=False,
+            start_stream=False,
+            tag=self.tag)
+        return TruncatedTailPipe(self.decrypter, tail_size=len(self.tag))
+
+    def write(self, data):
+        self.preamble_pipe.write(data)
+
+    def close(self):
+        real_size = self.decrypter.decrypted_content_size
+        return self.decrypter._end_stream(), real_size
+
+
+class BlobManager(object):
+    """
+    Ideally, the decrypting flow goes like this:
+
+    - GET a blob from remote server.
+    - Decrypt the preamble
+    - Allocate a zeroblob in the sqlcipher sink
+    - Mark the blob as unusable (ie, not verified)
+    - Decrypt the payload incrementally, and write chunks to sqlcipher
+      ** Is it possible to use a small buffer for the aes writer w/o
+      ** allocating all the memory in openssl?
+    - Finalize the AES decryption
+    - If preamble + payload verifies correctly, mark the blob as usable
+
+    """
+
+    def __init__(
+            self, local_path, remote, key, secret, user, token=None,
+            cert_file=None):
+        if local_path:
+            mkdir_p(os.path.dirname(local_path))
+            self.local = SQLiteBlobBackend(local_path, key)
+        self.remote = remote
+        self.secret = secret
+        self.user = user
+        self._client = HTTPClient(user, token, cert_file)
+
+    def close(self):
+        if hasattr(self, 'local') and self.local:
+            return self.local.close()
+
+    @defer.inlineCallbacks
+    def remote_list(self):
+        uri = urljoin(self.remote, self.user + '/')
+        data = yield self._client.get(uri)
+        defer.returnValue((yield data.json()))
+
+    def local_list(self):
+        return self.local.list()
+
+    @defer.inlineCallbacks
+    def send_missing(self):
+        our_blobs = yield self.local_list()
+        server_blobs = yield self.remote_list()
+        missing = [b_id for b_id in our_blobs if b_id not in server_blobs]
+        logger.info("Amount of documents missing on server: %s" % len(missing))
+        # TODO: Send concurrently when we are able to stream directly from db
+        for blob_id in missing:
+            fd = yield self.local.get(blob_id)
+            logger.info("Upload local blob: %s" % blob_id)
+            yield self._encrypt_and_upload(blob_id, fd)
+
+    @defer.inlineCallbacks
+    def fetch_missing(self):
+        # TODO: Use something to prioritize user requests over general new docs
+        our_blobs = yield self.local_list()
+        server_blobs = yield self.remote_list()
+        docs_we_want = [b_id for b_id in server_blobs if b_id not in our_blobs]
+        logger.info("Fetching new docs from server: %s" % len(docs_we_want))
+        # TODO: Fetch concurrently when we are able to stream directly into db
+        for blob_id in docs_we_want:
+            logger.info("Fetching new doc: %s" % blob_id)
+            yield self.get(blob_id)
+
+    @defer.inlineCallbacks
+    def put(self, doc, size):
+        if (yield self.local.exists(doc.blob_id)):
+            error_message = "Blob already exists: %s" % doc.blob_id
+            raise BlobAlreadyExistsError(error_message)
+        fd = doc.blob_fd
+        # TODO this is a tee really, but ok... could do db and upload
+        # concurrently. not sure if we'd gain something.
+        yield self.local.put(doc.blob_id, fd, size=size)
+        # In fact, some kind of pipe is needed here, where each write on db
+        # handle gets forwarded into a write on the connection handle
+        fd = yield self.local.get(doc.blob_id)
+        yield self._encrypt_and_upload(doc.blob_id, fd)
+
+    @defer.inlineCallbacks
+    def get(self, blob_id):
+        local_blob = yield self.local.get(blob_id)
+        if local_blob:
+            logger.info("Found blob in local database: %s" % blob_id)
+            defer.returnValue(local_blob)
+
+        result = yield self._download_and_decrypt(blob_id)
+
+        if not result:
+            defer.returnValue(None)
+        blob, size = result
+
+        if blob:
+            logger.info("Got decrypted blob of type: %s" % type(blob))
+            blob.seek(0)
+            yield self.local.put(blob_id, blob, size=size)
+            defer.returnValue((yield self.local.get(blob_id)))
+        else:
+            # XXX we shouldn't get here, but we will...
+            # lots of ugly error handling possible:
+            # 1. retry, might be network error
+            # 2. try later, maybe didn't finished streaming
+            # 3.. resignation, might be error while verifying
+            logger.error('sorry, dunno what happened')
+
+    @defer.inlineCallbacks
+    def _encrypt_and_upload(self, blob_id, fd):
+        # TODO ------------------------------------------
+        # this is wrong, is doing 2 stages.
+        # the crypto producer can be passed to
+        # the uploader and react as data is written.
+        # try to rewrite as a tube: pass the fd to aes and let aes writer
+        # produce data to the treq request fd.
+        # ------------------------------------------------
+        logger.info("Staring upload of blob: %s" % blob_id)
+        doc_info = DocInfo(blob_id, FIXED_REV)
+        uri = urljoin(self.remote, self.user + "/" + blob_id)
+        crypter = BlobEncryptor(doc_info, fd, secret=self.secret,
+                                armor=False)
+        fd = yield crypter.encrypt()
+        response = yield self._client.put(uri, data=fd)
+        check_http_status(response.code)
+        logger.info("Finished upload: %s" % (blob_id,))
+
+    @defer.inlineCallbacks
+    def _download_and_decrypt(self, blob_id):
+        logger.info("Staring download of blob: %s" % blob_id)
+        # TODO this needs to be connected in a tube
+        uri = urljoin(self.remote, self.user + '/' + blob_id)
+        data = yield self._client.get(uri)
+
+        if data.code == 404:
+            logger.warn("Blob not found in server: %s" % blob_id)
+            defer.returnValue(None)
+        elif not data.headers.hasHeader('Tag'):
+            logger.error("Server didn't send a tag header for: %s" % blob_id)
+            defer.returnValue(None)
+        tag = data.headers.getRawHeaders('Tag')[0]
+        tag = base64.urlsafe_b64decode(tag)
+        buf = DecrypterBuffer(blob_id, self.secret, tag)
+
+        # incrementally collect the body of the response
+        yield treq.collect(data, buf.write)
+        fd, size = buf.close()
+        logger.info("Finished download: (%s, %d)" % (blob_id, size))
+        defer.returnValue((fd, size))
+
+    @defer.inlineCallbacks
+    def delete(self, blob_id):
+        logger.info("Staring deletion of blob: %s" % blob_id)
+        yield self._delete_from_remote(blob_id)
+        if (yield self.local.exists(blob_id)):
+            yield self.local.delete(blob_id)
+
+    def _delete_from_remote(self, blob_id):
+        # TODO this needs to be connected in a tube
+        uri = urljoin(self.remote, self.user + '/' + blob_id)
+        return self._client.delete(uri)
+
+
+class SQLiteBlobBackend(object):
+
+    def __init__(self, path, key=None):
+        self.path = os.path.abspath(
+            os.path.join(path, 'soledad_blob.db'))
+        mkdir_p(os.path.dirname(self.path))
+        if not key:
+            raise ValueError('key cannot be None')
+        backend = 'pysqlcipher.dbapi2'
+        opts = sqlcipher.SQLCipherOptions(
+            '/tmp/ignored', binascii.b2a_hex(key),
+            is_raw_key=True, create=True)
+        pragmafun = partial(pragmas.set_init_pragmas, opts=opts)
+        openfun = _sqlcipherInitFactory(pragmafun)
+
+        self.dbpool = ConnectionPool(
+            backend, self.path, check_same_thread=False, timeout=5,
+            cp_openfun=openfun, cp_min=1, cp_max=2, cp_name='blob_pool')
+
+    def close(self):
+        from twisted._threads import AlreadyQuit
+        try:
+            self.dbpool.close()
+        except AlreadyQuit:
+            pass
+
+    @defer.inlineCallbacks
+    def put(self, blob_id, blob_fd, size=None):
+        logger.info("Saving blob in local database...")
+        insert = 'INSERT INTO blobs (blob_id, payload) VALUES (?, zeroblob(?))'
+        irow = yield self.dbpool.insertAndGetLastRowid(insert, (blob_id, size))
+        handle = yield self.dbpool.blob('blobs', 'payload', irow, 1)
+        blob_fd.seek(0)
+        # XXX I have to copy the buffer here so that I'm able to
+        # return a non-closed file to the caller (blobmanager.get)
+        # FIXME should remove this duplication!
+        # have a look at how treq does cope with closing the handle
+        # for uploading a file
+        producer = FileBodyProducer(blob_fd)
+        done = yield producer.startProducing(handle)
+        logger.info("Finished saving blob in local database.")
+        defer.returnValue(done)
+
+    @defer.inlineCallbacks
+    def get(self, blob_id):
+        # TODO we can also stream the blob value using sqlite
+        # incremental interface for blobs - and just return the raw fd instead
+        select = 'SELECT payload FROM blobs WHERE blob_id = ?'
+        result = yield self.dbpool.runQuery(select, (blob_id,))
+        if result:
+            defer.returnValue(BytesIO(str(result[0][0])))
+
+    @defer.inlineCallbacks
+    def list(self):
+        query = 'select blob_id from blobs'
+        result = yield self.dbpool.runQuery(query)
+        if result:
+            defer.returnValue([b_id[0] for b_id in result])
+        else:
+            defer.returnValue([])
+
+    @defer.inlineCallbacks
+    def exists(self, blob_id):
+        query = 'SELECT blob_id from blobs WHERE blob_id = ?'
+        result = yield self.dbpool.runQuery(query, (blob_id,))
+        defer.returnValue(bool(len(result)))
+
+    def delete(self, blob_id):
+        query = 'DELETE FROM blobs WHERE blob_id = ?'
+        return self.dbpool.runQuery(query, (blob_id,))
+
+
+def _init_blob_table(conn):
+    maybe_create = (
+        "CREATE TABLE IF NOT EXISTS "
+        "blobs ("
+        "blob_id PRIMARY KEY, "
+        "payload BLOB)")
+    conn.execute(maybe_create)
+
+
+def _sqlcipherInitFactory(fun):
+    def _initialize(conn):
+        fun(conn)
+        _init_blob_table(conn)
+    return _initialize
+
+
+#
+# testing facilities
+#
+
+@defer.inlineCallbacks
+def testit(reactor):
+    # configure logging to stdout
+    from twisted.python import log
+    import sys
+    log.startLogging(sys.stdout)
+
+    # parse command line arguments
+    import argparse
+
+    parser = argparse.ArgumentParser()
+    parser.add_argument('--url', default='http://localhost:9000/')
+    parser.add_argument('--path', default='/tmp/blobs')
+    parser.add_argument('--secret', default='secret')
+    parser.add_argument('--uuid', default='user')
+    parser.add_argument('--token', default=None)
+    parser.add_argument('--cert-file', default='')
+
+    subparsers = parser.add_subparsers(help='sub-command help', dest='action')
+
+    # parse upload command
+    parser_upload = subparsers.add_parser(
+        'upload', help='upload blob and bypass local db')
+    parser_upload.add_argument('payload')
+    parser_upload.add_argument('blob_id')
+
+    # parse download command
+    parser_download = subparsers.add_parser(
+        'download', help='download blob and bypass local db')
+    parser_download.add_argument('blob_id')
+    parser_download.add_argument('--output-file', default='/tmp/incoming-file')
+
+    # parse put command
+    parser_put = subparsers.add_parser(
+        'put', help='put blob in local db and upload')
+    parser_put.add_argument('payload')
+    parser_put.add_argument('blob_id')
+
+    # parse get command
+    parser_get = subparsers.add_parser(
+        'get', help='get blob from local db, get if needed')
+    parser_get.add_argument('blob_id')
+
+    # parse delete command
+    parser_get = subparsers.add_parser(
+        'delete', help='delete blob from local and remote db')
+    parser_get.add_argument('blob_id')
+
+    # parse list command
+    parser_get = subparsers.add_parser(
+        'list', help='list local and remote blob ids')
+
+    # parse send_missing command
+    parser_get = subparsers.add_parser(
+        'send_missing', help='send all pending upload blobs')
+
+    # parse send_missing command
+    parser_get = subparsers.add_parser(
+        'fetch_missing', help='fetch all new server blobs')
+
+    # parse arguments
+    args = parser.parse_args()
+
+    # TODO convert these into proper unittests
+
+    def _manager():
+        mkdir_p(os.path.dirname(args.path))
+        manager = BlobManager(
+            args.path, args.url,
+            'A' * 32, args.secret,
+            args.uuid, args.token, args.cert_file)
+        return manager
+
+    @defer.inlineCallbacks
+    def _upload(blob_id, payload):
+        logger.info(":: Starting upload only: %s" % str((blob_id, payload)))
+        manager = _manager()
+        with open(payload, 'r') as fd:
+            yield manager._encrypt_and_upload(blob_id, fd)
+        logger.info(":: Finished upload only: %s" % str((blob_id, payload)))
+
+    @defer.inlineCallbacks
+    def _download(blob_id):
+        logger.info(":: Starting download only: %s" % blob_id)
+        manager = _manager()
+        result = yield manager._download_and_decrypt(blob_id)
+        logger.info(":: Result of download: %s" % str(result))
+        if result:
+            fd, _ = result
+            with open(args.output_file, 'w') as f:
+                logger.info(":: Writing data to %s" % args.output_file)
+                f.write(fd.read())
+        logger.info(":: Finished download only: %s" % blob_id)
+
+    @defer.inlineCallbacks
+    def _put(blob_id, payload):
+        logger.info(":: Starting full put: %s" % blob_id)
+        manager = _manager()
+        size = os.path.getsize(payload)
+        with open(payload) as fd:
+            doc = BlobDoc(fd, blob_id)
+            result = yield manager.put(doc, size=size)
+        logger.info(":: Result of put: %s" % str(result))
+        logger.info(":: Finished full put: %s" % blob_id)
+
+    @defer.inlineCallbacks
+    def _get(blob_id):
+        logger.info(":: Starting full get: %s" % blob_id)
+        manager = _manager()
+        fd = yield manager.get(blob_id)
+        if fd:
+            logger.info(":: Result of get: " + fd.getvalue())
+        logger.info(":: Finished full get: %s" % blob_id)
+
+    @defer.inlineCallbacks
+    def _delete(blob_id):
+        logger.info(":: Starting deletion of: %s" % blob_id)
+        manager = _manager()
+        yield manager.delete(blob_id)
+        logger.info(":: Finished deletion of: %s" % blob_id)
+
+    @defer.inlineCallbacks
+    def _list():
+        logger.info(":: Listing local blobs")
+        manager = _manager()
+        local_list = yield manager.local_list()
+        logger.info(":: Local list: %s" % local_list)
+        logger.info(":: Listing remote blobs")
+        remote_list = yield manager.remote_list()
+        logger.info(":: Remote list: %s" % remote_list)
+
+    @defer.inlineCallbacks
+    def _send_missing():
+        logger.info(":: Sending local pending upload docs")
+        manager = _manager()
+        yield manager.send_missing()
+        logger.info(":: Finished sending missing docs")
+
+    @defer.inlineCallbacks
+    def _fetch_missing():
+        logger.info(":: Fetching remote new docs")
+        manager = _manager()
+        yield manager.fetch_missing()
+        logger.info(":: Finished fetching new docs")
+
+    if args.action == 'upload':
+        yield _upload(args.blob_id, args.payload)
+    elif args.action == 'download':
+        yield _download(args.blob_id)
+    elif args.action == 'put':
+        yield _put(args.blob_id, args.payload)
+    elif args.action == 'get':
+        yield _get(args.blob_id)
+    elif args.action == 'delete':
+        yield _delete(args.blob_id)
+    elif args.action == 'list':
+        yield _list()
+    elif args.action == 'send_missing':
+        yield _send_missing()
+    elif args.action == 'fetch_missing':
+        yield _fetch_missing()
+
+
+if __name__ == '__main__':
+    from twisted.internet.task import react
+    react(testit)
diff --git a/src/leap/soledad/client/_db/dbschema.sql b/src/leap/soledad/client/_db/dbschema.sql
new file mode 100644
index 00000000..ae027fc5
--- /dev/null
+++ b/src/leap/soledad/client/_db/dbschema.sql
@@ -0,0 +1,42 @@
+-- Database schema
+CREATE TABLE transaction_log (
+    generation INTEGER PRIMARY KEY AUTOINCREMENT,
+    doc_id TEXT NOT NULL,
+    transaction_id TEXT NOT NULL
+);
+CREATE TABLE document (
+    doc_id TEXT PRIMARY KEY,
+    doc_rev TEXT NOT NULL,
+    content TEXT
+);
+CREATE TABLE document_fields (
+    doc_id TEXT NOT NULL,
+    field_name TEXT NOT NULL,
+    value TEXT
+);
+CREATE INDEX document_fields_field_value_doc_idx
+    ON document_fields(field_name, value, doc_id);
+
+CREATE TABLE sync_log (
+    replica_uid TEXT PRIMARY KEY,
+    known_generation INTEGER,
+    known_transaction_id TEXT
+);
+CREATE TABLE conflicts (
+    doc_id TEXT,
+    doc_rev TEXT,
+    content TEXT,
+    CONSTRAINT conflicts_pkey PRIMARY KEY (doc_id, doc_rev)
+);
+CREATE TABLE index_definitions (
+    name TEXT,
+    offset INT,
+    field TEXT,
+    CONSTRAINT index_definitions_pkey PRIMARY KEY (name, offset)
+);
+create index index_definitions_field on index_definitions(field);
+CREATE TABLE u1db_config (
+    name TEXT PRIMARY KEY,
+    value TEXT
+);
+INSERT INTO u1db_config VALUES ('sql_schema', '0');
diff --git a/src/leap/soledad/client/_db/pragmas.py b/src/leap/soledad/client/_db/pragmas.py
new file mode 100644
index 00000000..870ed63e
--- /dev/null
+++ b/src/leap/soledad/client/_db/pragmas.py
@@ -0,0 +1,379 @@
+# -*- coding: utf-8 -*-
+# pragmas.py
+# Copyright (C) 2013, 2014 LEAP
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+"""
+Different pragmas used in the initialization of the SQLCipher database.
+"""
+import string
+import threading
+import os
+
+from leap.soledad.common import soledad_assert
+from leap.soledad.common.log import getLogger
+
+
+logger = getLogger(__name__)
+
+
+_db_init_lock = threading.Lock()
+
+
+def set_init_pragmas(conn, opts=None, extra_queries=None):
+    """
+    Set the initialization pragmas.
+
+    This includes the crypto pragmas, and any other options that must
+    be passed early to sqlcipher db.
+    """
+    soledad_assert(opts is not None)
+    extra_queries = [] if extra_queries is None else extra_queries
+    with _db_init_lock:
+        # only one execution path should initialize the db
+        _set_init_pragmas(conn, opts, extra_queries)
+
+
+def _set_init_pragmas(conn, opts, extra_queries):
+
+    sync_off = os.environ.get('LEAP_SQLITE_NOSYNC')
+    memstore = os.environ.get('LEAP_SQLITE_MEMSTORE')
+    nowal = os.environ.get('LEAP_SQLITE_NOWAL')
+
+    set_crypto_pragmas(conn, opts)
+
+    if not nowal:
+        set_write_ahead_logging(conn)
+    if sync_off:
+        set_synchronous_off(conn)
+    else:
+        set_synchronous_normal(conn)
+    if memstore:
+        set_mem_temp_store(conn)
+
+    for query in extra_queries:
+        conn.cursor().execute(query)
+
+
+def set_crypto_pragmas(db_handle, sqlcipher_opts):
+    """
+    Set cryptographic params (key, cipher, KDF number of iterations and
+    cipher page size).
+
+    :param db_handle:
+    :type db_handle:
+    :param sqlcipher_opts: options for the SQLCipherDatabase
+    :type sqlcipher_opts: SQLCipherOpts instance
+    """
+    # XXX assert CryptoOptions
+    opts = sqlcipher_opts
+    _set_key(db_handle, opts.key, opts.is_raw_key)
+    _set_cipher(db_handle, opts.cipher)
+    _set_kdf_iter(db_handle, opts.kdf_iter)
+    _set_cipher_page_size(db_handle, opts.cipher_page_size)
+
+
+def _set_key(db_handle, key, is_raw_key):
+    """
+    Set the ``key`` for use with the database.
+
+    The process of creating a new, encrypted database is called 'keying'
+    the database. SQLCipher uses just-in-time key derivation at the point
+    it is first needed for an operation. This means that the key (and any
+    options) must be set before the first operation on the database. As
+    soon as the database is touched (e.g. SELECT, CREATE TABLE, UPDATE,
+    etc.) and pages need to be read or written, the key is prepared for
+    use.
+
+    Implementation Notes:
+
+    * PRAGMA key should generally be called as the first operation on a
+        database.
+
+    :param key: The key for use with the database.
+    :type key: str
+    :param is_raw_key:
+        Whether C{key} is a raw 64-char hex string or a passphrase that should
+        be hashed to obtain the encyrption key.
+    :type is_raw_key: bool
+    """
+    if is_raw_key:
+        _set_key_raw(db_handle, key)
+    else:
+        _set_key_passphrase(db_handle, key)
+
+
+def _set_key_passphrase(db_handle, passphrase):
+    """
+    Set a passphrase for encryption key derivation.
+
+    The key itself can be a passphrase, which is converted to a key using
+    PBKDF2 key derivation. The result is used as the encryption key for
+    the database. By using this method, there is no way to alter the KDF;
+    if you want to do so you should use a raw key instead and derive the
+    key using your own KDF.
+
+    :param db_handle: A handle to the SQLCipher database.
+    :type db_handle: pysqlcipher.Connection
+    :param passphrase: The passphrase used to derive the encryption key.
+    :type passphrase: str
+    """
+    db_handle.cursor().execute("PRAGMA key = '%s'" % passphrase)
+
+
+def _set_key_raw(db_handle, key):
+    """
+    Set a raw hexadecimal encryption key.
+
+    It is possible to specify an exact byte sequence using a blob literal.
+    With this method, it is the calling application's responsibility to
+    ensure that the data provided is a 64 character hex string, which will
+    be converted directly to 32 bytes (256 bits) of key data.
+
+    :param db_handle: A handle to the SQLCipher database.
+    :type db_handle: pysqlcipher.Connection
+    :param key: A 64 character hex string.
+    :type key: str
+    """
+    if not all(c in string.hexdigits for c in key):
+        raise NotAnHexString(key)
+    db_handle.cursor().execute('PRAGMA key = "x\'%s"' % key)
+
+
+def _set_cipher(db_handle, cipher='aes-256-cbc'):
+    """
+    Set the cipher and mode to use for symmetric encryption.
+
+    SQLCipher uses aes-256-cbc as the default cipher and mode of
+    operation. It is possible to change this, though not generally
+    recommended, using PRAGMA cipher.
+
+    SQLCipher makes direct use of libssl, so all cipher options available
+    to libssl are also available for use with SQLCipher. See `man enc` for
+    OpenSSL's supported ciphers.
+
+    Implementation Notes:
+
+    * PRAGMA cipher must be called after PRAGMA key and before the first
+        actual database operation or it will have no effect.
+
+    * If a non-default value is used PRAGMA cipher to create a database,
+        it must also be called every time that database is opened.
+
+    * SQLCipher does not implement its own encryption. Instead it uses the
+        widely available and peer-reviewed OpenSSL libcrypto for all
+        cryptographic functions.
+
+    :param db_handle: A handle to the SQLCipher database.
+    :type db_handle: pysqlcipher.Connection
+    :param cipher: The cipher and mode to use.
+    :type cipher: str
+    """
+    db_handle.cursor().execute("PRAGMA cipher = '%s'" % cipher)
+
+
+def _set_kdf_iter(db_handle, kdf_iter=4000):
+    """
+    Set the number of iterations for the key derivation function.
+
+    SQLCipher uses PBKDF2 key derivation to strengthen the key and make it
+    resistent to brute force and dictionary attacks. The default
+    configuration uses 4000 PBKDF2 iterations (effectively 16,000 SHA1
+    operations). PRAGMA kdf_iter can be used to increase or decrease the
+    number of iterations used.
+
+    Implementation Notes:
+
+    * PRAGMA kdf_iter must be called after PRAGMA key and before the first
+        actual database operation or it will have no effect.
+
+    * If a non-default value is used PRAGMA kdf_iter to create a database,
+        it must also be called every time that database is opened.
+
+    * It is not recommended to reduce the number of iterations if a
+        passphrase is in use.
+
+    :param db_handle: A handle to the SQLCipher database.
+    :type db_handle: pysqlcipher.Connection
+    :param kdf_iter: The number of iterations to use.
+    :type kdf_iter: int
+    """
+    db_handle.cursor().execute("PRAGMA kdf_iter = '%d'" % kdf_iter)
+
+
+def _set_cipher_page_size(db_handle, cipher_page_size=1024):
+    """
+    Set the page size of the encrypted database.
+
+    SQLCipher 2 introduced the new PRAGMA cipher_page_size that can be
+    used to adjust the page size for the encrypted database. The default
+    page size is 1024 bytes, but it can be desirable for some applications
+    to use a larger page size for increased performance. For instance,
+    some recent testing shows that increasing the page size can noticeably
+    improve performance (5-30%) for certain queries that manipulate a
+    large number of pages (e.g. selects without an index, large inserts in
+    a transaction, big deletes).
+
+    To adjust the page size, call the pragma immediately after setting the
+    key for the first time and each subsequent time that you open the
+    database.
+
+    Implementation Notes:
+
+    * PRAGMA cipher_page_size must be called after PRAGMA key and before
+        the first actual database operation or it will have no effect.
+
+    * If a non-default value is used PRAGMA cipher_page_size to create a
+        database, it must also be called every time that database is opened.
+
+    :param db_handle: A handle to the SQLCipher database.
+    :type db_handle: pysqlcipher.Connection
+    :param cipher_page_size: The page size.
+    :type cipher_page_size: int
+    """
+    db_handle.cursor().execute(
+        "PRAGMA cipher_page_size = '%d'" % cipher_page_size)
+
+
+# XXX UNUSED ?
+def set_rekey(db_handle, new_key, is_raw_key):
+    """
+    Change the key of an existing encrypted database.
+
+    To change the key on an existing encrypted database, it must first be
+    unlocked with the current encryption key. Once the database is
+    readable and writeable, PRAGMA rekey can be used to re-encrypt every
+    page in the database with a new key.
+
+    * PRAGMA rekey must be called after PRAGMA key. It can be called at any
+        time once the database is readable.
+
+    * PRAGMA rekey can not be used to encrypted a standard SQLite
+        database! It is only useful for changing the key on an existing
+        database.
+
+    * Previous versions of SQLCipher provided a PRAGMA rekey_cipher and
+        code>PRAGMA rekey_kdf_iter. These are deprecated and should not be
+        used. Instead, use sqlcipher_export().
+
+    :param db_handle: A handle to the SQLCipher database.
+    :type db_handle: pysqlcipher.Connection
+    :param new_key: The new key.
+    :type new_key: str
+    :param is_raw_key: Whether C{password} is a raw 64-char hex string or a
+                    passphrase that should be hashed to obtain the encyrption
+                    key.
+    :type is_raw_key: bool
+    """
+    if is_raw_key:
+        _set_rekey_raw(db_handle, new_key)
+    else:
+        _set_rekey_passphrase(db_handle, new_key)
+
+
+def _set_rekey_passphrase(db_handle, passphrase):
+    """
+    Change the passphrase for encryption key derivation.
+
+    The key itself can be a passphrase, which is converted to a key using
+    PBKDF2 key derivation. The result is used as the encryption key for
+    the database.
+
+    :param db_handle: A handle to the SQLCipher database.
+    :type db_handle: pysqlcipher.Connection
+    :param passphrase: The passphrase used to derive the encryption key.
+    :type passphrase: str
+    """
+    db_handle.cursor().execute("PRAGMA rekey = '%s'" % passphrase)
+
+
+def _set_rekey_raw(db_handle, key):
+    """
+    Change the raw hexadecimal encryption key.
+
+    It is possible to specify an exact byte sequence using a blob literal.
+    With this method, it is the calling application's responsibility to
+    ensure that the data provided is a 64 character hex string, which will
+    be converted directly to 32 bytes (256 bits) of key data.
+
+    :param db_handle: A handle to the SQLCipher database.
+    :type db_handle: pysqlcipher.Connection
+    :param key: A 64 character hex string.
+    :type key: str
+    """
+    if not all(c in string.hexdigits for c in key):
+        raise NotAnHexString(key)
+    db_handle.cursor().execute('PRAGMA rekey = "x\'%s"' % key)
+
+
+def set_synchronous_off(db_handle):
+    """
+    Change the setting of the "synchronous" flag to OFF.
+    """
+    logger.debug("sqlcipher: setting synchronous off")
+    db_handle.cursor().execute('PRAGMA synchronous=OFF')
+
+
+def set_synchronous_normal(db_handle):
+    """
+    Change the setting of the "synchronous" flag to NORMAL.
+    """
+    logger.debug("sqlcipher: setting synchronous normal")
+    db_handle.cursor().execute('PRAGMA synchronous=NORMAL')
+
+
+def set_mem_temp_store(db_handle):
+    """
+    Use a in-memory store for temporary tables.
+    """
+    logger.debug("sqlcipher: setting temp_store memory")
+    db_handle.cursor().execute('PRAGMA temp_store=MEMORY')
+
+
+def set_write_ahead_logging(db_handle):
+    """
+    Enable write-ahead logging, and set the autocheckpoint to 50 pages.
+
+    Setting the autocheckpoint to a small value, we make the reads not
+    suffer too much performance degradation.
+
+    From the sqlite docs:
+
+    "There is a tradeoff between average read performance and average write
+    performance. To maximize the read performance, one wants to keep the
+    WAL as small as possible and hence run checkpoints frequently, perhaps
+    as often as every COMMIT. To maximize write performance, one wants to
+    amortize the cost of each checkpoint over as many writes as possible,
+    meaning that one wants to run checkpoints infrequently and let the WAL
+    grow as large as possible before each checkpoint. The decision of how
+    often to run checkpoints may therefore vary from one application to
+    another depending on the relative read and write performance
+    requirements of the application. The default strategy is to run a
+    checkpoint once the WAL reaches 1000 pages"
+    """
+    logger.debug("sqlcipher: setting write-ahead logging")
+    db_handle.cursor().execute('PRAGMA journal_mode=WAL')
+
+    # The optimum value can still use a little bit of tuning, but we favor
+    # small sizes of the WAL file to get fast reads, since we assume that
+    # the writes will be quick enough to not block too much.
+
+    db_handle.cursor().execute('PRAGMA wal_autocheckpoint=50')
+
+
+class NotAnHexString(Exception):
+    """
+    Raised when trying to (raw) key the database with a non-hex string.
+    """
+    pass
diff --git a/src/leap/soledad/client/_db/sqlcipher.py b/src/leap/soledad/client/_db/sqlcipher.py
new file mode 100644
index 00000000..d22017bd
--- /dev/null
+++ b/src/leap/soledad/client/_db/sqlcipher.py
@@ -0,0 +1,633 @@
+# -*- coding: utf-8 -*-
+# sqlcipher.py
+# Copyright (C) 2013, 2014 LEAP
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+"""
+A U1DB backend that uses SQLCipher as its persistence layer.
+
+The SQLCipher API (http://sqlcipher.net/sqlcipher-api/) is fully implemented,
+with the exception of the following statements:
+
+  * PRAGMA cipher_use_hmac
+  * PRAGMA cipher_default_use_mac
+
+SQLCipher 2.0 introduced a per-page HMAC to validate that the page data has
+not be tampered with. By default, when creating or opening a database using
+SQLCipher 2, SQLCipher will attempt to use an HMAC check. This change in
+database format means that SQLCipher 2 can't operate on version 1.1.x
+databases by default. Thus, in order to provide backward compatibility with
+SQLCipher 1.1.x, PRAGMA cipher_use_hmac can be used to disable the HMAC
+functionality on specific databases.
+
+In some very specific cases, it is not possible to call PRAGMA cipher_use_hmac
+as one of the first operations on a database. An example of this is when
+trying to ATTACH a 1.1.x database to the main database. In these cases PRAGMA
+cipher_default_use_hmac can be used to globally alter the default use of HMAC
+when opening a database.
+
+So, as the statements above were introduced for backwards compatibility with
+SQLCipher 1.1 databases, we do not implement them as all SQLCipher databases
+handled by Soledad should be created by SQLCipher >= 2.0.
+"""
+import os
+import sys
+
+from functools import partial
+
+from twisted.internet import reactor
+from twisted.internet import defer
+from twisted.enterprise import adbapi
+
+from leap.soledad.common.log import getLogger
+from leap.soledad.common.l2db import errors as u1db_errors
+from leap.soledad.common.errors import DatabaseAccessError
+
+from leap.soledad.client.http_target import SoledadHTTPSyncTarget
+from leap.soledad.client.sync import SoledadSynchronizer
+
+from .._document import Document
+from . import sqlite
+from . import pragmas
+
+if sys.version_info[0] < 3:
+    from pysqlcipher import dbapi2 as sqlcipher_dbapi2
+else:
+    from pysqlcipher3 import dbapi2 as sqlcipher_dbapi2
+
+logger = getLogger(__name__)
+
+
+# Monkey-patch u1db.backends.sqlite with pysqlcipher.dbapi2
+sqlite.dbapi2 = sqlcipher_dbapi2
+
+
+# we may want to collect statistics from the sync process
+DO_STATS = False
+if os.environ.get('SOLEDAD_STATS'):
+    DO_STATS = True
+
+
+def initialize_sqlcipher_db(opts, on_init=None, check_same_thread=True):
+    """
+    Initialize a SQLCipher database.
+
+    :param opts:
+    :type opts: SQLCipherOptions
+    :param on_init: a tuple of queries to be executed on initialization
+    :type on_init: tuple
+    :return: pysqlcipher.dbapi2.Connection
+    """
+    # Note: There seemed to be a bug in sqlite 3.5.9 (with python2.6)
+    #       where without re-opening the database on Windows, it
+    #       doesn't see the transaction that was just committed
+    # Removing from here now, look at the pysqlite implementation if the
+    # bug shows up in windows.
+
+    if not os.path.isfile(opts.path) and not opts.create:
+        raise u1db_errors.DatabaseDoesNotExist()
+
+    conn = sqlcipher_dbapi2.connect(
+        opts.path, check_same_thread=check_same_thread)
+    pragmas.set_init_pragmas(conn, opts, extra_queries=on_init)
+    return conn
+
+
+def initialize_sqlcipher_adbapi_db(opts, extra_queries=None):
+    from leap.soledad.client import sqlcipher_adbapi
+    return sqlcipher_adbapi.getConnectionPool(
+        opts, extra_queries=extra_queries)
+
+
+class SQLCipherOptions(object):
+    """
+    A container with options for the initialization of an SQLCipher database.
+    """
+
+    @classmethod
+    def copy(cls, source, path=None, key=None, create=None,
+             is_raw_key=None, cipher=None, kdf_iter=None,
+             cipher_page_size=None, sync_db_key=None):
+        """
+        Return a copy of C{source} with parameters different than None
+        replaced by new values.
+        """
+        local_vars = locals()
+        args = []
+        kwargs = {}
+
+        for name in ["path", "key"]:
+            val = local_vars[name]
+            if val is not None:
+                args.append(val)
+            else:
+                args.append(getattr(source, name))
+
+        for name in ["create", "is_raw_key", "cipher", "kdf_iter",
+                     "cipher_page_size", "sync_db_key"]:
+            val = local_vars[name]
+            if val is not None:
+                kwargs[name] = val
+            else:
+                kwargs[name] = getattr(source, name)
+
+        return SQLCipherOptions(*args, **kwargs)
+
+    def __init__(self, path, key, create=True, is_raw_key=False,
+                 cipher='aes-256-cbc', kdf_iter=4000, cipher_page_size=1024,
+                 sync_db_key=None):
+        """
+        :param path: The filesystem path for the database to open.
+        :type path: str
+        :param create:
+            True/False, should the database be created if it doesn't
+            already exist?
+        :param create: bool
+        :param is_raw_key:
+            Whether ``password`` is a raw 64-char hex string or a passphrase
+            that should be hashed to obtain the encyrption key.
+        :type raw_key: bool
+        :param cipher: The cipher and mode to use.
+        :type cipher: str
+        :param kdf_iter: The number of iterations to use.
+        :type kdf_iter: int
+        :param cipher_page_size: The page size.
+        :type cipher_page_size: int
+        """
+        self.path = path
+        self.key = key
+        self.is_raw_key = is_raw_key
+        self.create = create
+        self.cipher = cipher
+        self.kdf_iter = kdf_iter
+        self.cipher_page_size = cipher_page_size
+        self.sync_db_key = sync_db_key
+
+    def __str__(self):
+        """
+        Return string representation of options, for easy debugging.
+
+        :return: String representation of options.
+        :rtype: str
+        """
+        attr_names = filter(lambda a: not a.startswith('_'), dir(self))
+        attr_str = []
+        for a in attr_names:
+            attr_str.append(a + "=" + str(getattr(self, a)))
+        name = self.__class__.__name__
+        return "%s(%s)" % (name, ', '.join(attr_str))
+
+
+#
+# The SQLCipher database
+#
+
+class SQLCipherDatabase(sqlite.SQLitePartialExpandDatabase):
+    """
+    A U1DB implementation that uses SQLCipher as its persistence layer.
+    """
+
+    # The attribute _index_storage_value will be used as the lookup key for the
+    # implementation of the SQLCipher storage backend.
+    _index_storage_value = 'expand referenced encrypted'
+
+    def __init__(self, opts):
+        """
+        Connect to an existing SQLCipher database, creating a new sqlcipher
+        database file if needed.
+
+        *** IMPORTANT ***
+
+        Don't forget to close the database after use by calling the close()
+        method otherwise some resources might not be freed and you may
+        experience several kinds of leakages.
+
+        *** IMPORTANT ***
+
+        :param opts: options for initialization of the SQLCipher database.
+        :type opts: SQLCipherOptions
+        """
+        # ensure the db is encrypted if the file already exists
+        if os.path.isfile(opts.path):
+            self._db_handle = _assert_db_is_encrypted(opts)
+        else:
+            # connect to the sqlcipher database
+            self._db_handle = initialize_sqlcipher_db(opts)
+
+        # TODO ---------------------------------------------------
+        # Everything else in this initialization has to be factored
+        # out, so it can be used from SoledadSQLCipherWrapper.__init__
+        # too.
+        # ---------------------------------------------------------
+
+        self._ensure_schema()
+        self.set_document_factory(doc_factory)
+        self._prime_replica_uid()
+
+    def _prime_replica_uid(self):
+        """
+        In the u1db implementation, _replica_uid is a property
+        that returns the value in _real_replica_uid, and does
+        a db query if no value found.
+        Here we prime the replica uid during initialization so
+        that we don't have to wait for the query afterwards.
+        """
+        self._real_replica_uid = None
+        self._get_replica_uid()
+
+    def _extra_schema_init(self, c):
+        """
+        Add any extra fields, etc to the basic table definitions.
+
+        This method is called by u1db.backends.sqlite_backend._initialize()
+        method, which is executed when the database schema is created. Here,
+        we use it to include the "syncable" property for LeapDocuments.
+
+        :param c: The cursor for querying the database.
+        :type c: dbapi2.cursor
+        """
+        c.execute(
+            'ALTER TABLE document '
+            'ADD COLUMN syncable BOOL NOT NULL DEFAULT TRUE')
+
+    #
+    # SQLCipher API methods
+    #
+
+    # Extra query methods: extensions to the base u1db sqlite implmentation.
+
+    def get_count_from_index(self, index_name, *key_values):
+        """
+        Return the count for a given combination of index_name
+        and key values.
+
+        Extension method made from similar methods in u1db version 13.09
+
+        :param index_name: The index to query
+        :type index_name: str
+        :param key_values: values to match. eg, if you have
+                           an index with 3 fields then you would have:
+                           get_from_index(index_name, val1, val2, val3)
+        :type key_values: tuple
+        :return: count.
+        :rtype: int
+        """
+        c = self._db_handle.cursor()
+        definition = self._get_index_definition(index_name)
+
+        if len(key_values) != len(definition):
+            raise u1db_errors.InvalidValueForIndex()
+        tables = ["document_fields d%d" % i for i in range(len(definition))]
+        novalue_where = ["d.doc_id = d%d.doc_id"
+                         " AND d%d.field_name = ?"
+                         % (i, i) for i in range(len(definition))]
+        exact_where = [novalue_where[i] + (" AND d%d.value = ?" % (i,))
+                       for i in range(len(definition))]
+        args = []
+        where = []
+        for idx, (field, value) in enumerate(zip(definition, key_values)):
+            args.append(field)
+            where.append(exact_where[idx])
+            args.append(value)
+
+        tables = ["document_fields d%d" % i for i in range(len(definition))]
+        statement = (
+            "SELECT COUNT(*) FROM document d, %s WHERE %s " % (
+                ', '.join(tables),
+                ' AND '.join(where),
+            ))
+        try:
+            c.execute(statement, tuple(args))
+        except sqlcipher_dbapi2.OperationalError as e:
+            raise sqlcipher_dbapi2.OperationalError(
+                str(e) + '\nstatement: %s\nargs: %s\n' % (statement, args))
+        res = c.fetchall()
+        return res[0][0]
+
+    def close(self):
+        """
+        Close db connections.
+        """
+        # TODO should be handled by adbapi instead
+        # TODO syncdb should be stopped first
+
+        if logger is not None:  # logger might be none if called from __del__
+            logger.debug("SQLCipher backend: closing")
+
+        # close the actual database
+        if getattr(self, '_db_handle', False):
+            self._db_handle.close()
+            self._db_handle = None
+
+    # indexes
+
+    def _put_and_update_indexes(self, old_doc, doc):
+        """
+        Update a document and all indexes related to it.
+
+        :param old_doc: The old version of the document.
+        :type old_doc: u1db.Document
+        :param doc: The new version of the document.
+        :type doc: u1db.Document
+        """
+        sqlite.SQLitePartialExpandDatabase._put_and_update_indexes(
+            self, old_doc, doc)
+        c = self._db_handle.cursor()
+        c.execute('UPDATE document SET syncable=? WHERE doc_id=?',
+                  (doc.syncable, doc.doc_id))
+
+    def _get_doc(self, doc_id, check_for_conflicts=False):
+        """
+        Get just the document content, without fancy handling.
+
+        :param doc_id: The unique document identifier
+        :type doc_id: str
+        :param include_deleted: If set to True, deleted documents will be
+            returned with empty content. Otherwise asking for a deleted
+            document will return None.
+        :type include_deleted: bool
+
+        :return: a Document object.
+        :type: u1db.Document
+        """
+        doc = sqlite.SQLitePartialExpandDatabase._get_doc(
+            self, doc_id, check_for_conflicts)
+        if doc:
+            c = self._db_handle.cursor()
+            c.execute('SELECT syncable FROM document WHERE doc_id=?',
+                      (doc.doc_id,))
+            result = c.fetchone()
+            doc.syncable = bool(result[0])
+        return doc
+
+    def __del__(self):
+        """
+        Free resources when deleting or garbage collecting the database.
+
+        This is only here to minimze problems if someone ever forgets to call
+        the close() method after using the database; you should not rely on
+        garbage collecting to free up the database resources.
+        """
+        self.close()
+
+
+class SQLCipherU1DBSync(SQLCipherDatabase):
+    """
+    Soledad syncer implementation.
+    """
+
+    """
+    The name of the local symmetrically encrypted documents to
+    sync database file.
+    """
+    LOCAL_SYMMETRIC_SYNC_FILE_NAME = 'sync.u1db'
+
+    """
+    Period or recurrence of the Looping Call that will do the encryption to the
+    syncdb (in seconds).
+    """
+    ENCRYPT_LOOP_PERIOD = 1
+
+    def __init__(self, opts, soledad_crypto, replica_uid, cert_file):
+        self._opts = opts
+        self._path = opts.path
+        self._crypto = soledad_crypto
+        self.__replica_uid = replica_uid
+        self._cert_file = cert_file
+
+        # storage for the documents received during a sync
+        self.received_docs = []
+
+        self.running = False
+        self._db_handle = None
+
+        # initialize the main db before scheduling a start
+        self._initialize_main_db()
+        self._reactor = reactor
+        self._reactor.callWhenRunning(self._start)
+
+        if DO_STATS:
+            self.sync_phase = None
+
+    def commit(self):
+        self._db_handle.commit()
+
+    @property
+    def _replica_uid(self):
+        return str(self.__replica_uid)
+
+    def _start(self):
+        if not self.running:
+            self.running = True
+
+    def _initialize_main_db(self):
+        try:
+            self._db_handle = initialize_sqlcipher_db(
+                self._opts, check_same_thread=False)
+            self._real_replica_uid = None
+            self._ensure_schema()
+            self.set_document_factory(doc_factory)
+        except sqlcipher_dbapi2.DatabaseError as e:
+            raise DatabaseAccessError(str(e))
+
+    @defer.inlineCallbacks
+    def sync(self, url, creds=None):
+        """
+        Synchronize documents with remote replica exposed at url.
+
+        It is not safe to initiate more than one sync process and let them run
+        concurrently. It is responsibility of the caller to ensure that there
+        are no concurrent sync processes running. This is currently controlled
+        by the main Soledad object because it may also run post-sync hooks,
+        which should be run while the lock is locked.
+
+        :param url: The url of the target replica to sync with.
+        :type url: str
+        :param creds: optional dictionary giving credentials to authorize the
+                      operation with the server.
+        :type creds: dict
+
+        :return:
+            A Deferred, that will fire with the local generation (type `int`)
+            before the synchronisation was performed.
+        :rtype: Deferred
+        """
+        syncer = self._get_syncer(url, creds=creds)
+        if DO_STATS:
+            self.sync_phase = syncer.sync_phase
+            self.syncer = syncer
+            self.sync_exchange_phase = syncer.sync_exchange_phase
+        local_gen_before_sync = yield syncer.sync()
+        self.received_docs = syncer.received_docs
+        defer.returnValue(local_gen_before_sync)
+
+    def _get_syncer(self, url, creds=None):
+        """
+        Get a synchronizer for ``url`` using ``creds``.
+
+        :param url: The url of the target replica to sync with.
+        :type url: str
+        :param creds: optional dictionary giving credentials.
+                      to authorize the operation with the server.
+        :type creds: dict
+
+        :return: A synchronizer.
+        :rtype: Synchronizer
+        """
+        return SoledadSynchronizer(
+            self,
+            SoledadHTTPSyncTarget(
+                url,
+                # XXX is the replica_uid ready?
+                self._replica_uid,
+                creds=creds,
+                crypto=self._crypto,
+                cert_file=self._cert_file))
+
+    #
+    # Symmetric encryption of syncing docs
+    #
+
+    def get_generation(self):
+        # FIXME
+        # XXX this SHOULD BE a callback
+        return self._get_generation()
+
+
+class U1DBSQLiteBackend(sqlite.SQLitePartialExpandDatabase):
+    """
+    A very simple wrapper for u1db around sqlcipher backend.
+
+    Instead of initializing the database on the fly, it just uses an existing
+    connection that is passed to it in the initializer.
+
+    It can be used in tests and debug runs to initialize the adbapi with plain
+    sqlite connections, decoupled from the sqlcipher layer.
+    """
+
+    def __init__(self, conn):
+        self._db_handle = conn
+        self._real_replica_uid = None
+        self._ensure_schema()
+        self._factory = Document
+
+
+class SoledadSQLCipherWrapper(SQLCipherDatabase):
+    """
+    A wrapper for u1db that uses the Soledad-extended sqlcipher backend.
+
+    Instead of initializing the database on the fly, it just uses an existing
+    connection that is passed to it in the initializer.
+
+    It can be used from adbapi to initialize a soledad database after
+    getting a regular connection to a sqlcipher database.
+    """
+    def __init__(self, conn, opts):
+        self._db_handle = conn
+        self._real_replica_uid = None
+        self._ensure_schema()
+        self.set_document_factory(doc_factory)
+        self._prime_replica_uid()
+
+
+def _assert_db_is_encrypted(opts):
+    """
+    Assert that the sqlcipher file contains an encrypted database.
+
+    When opening an existing database, PRAGMA key will not immediately
+    throw an error if the key provided is incorrect. To test that the
+    database can be successfully opened with the provided key, it is
+    necessary to perform some operation on the database (i.e. read from
+    it) and confirm it is success.
+
+    The easiest way to do this is select off the sqlite_master table,
+    which will attempt to read the first page of the database and will
+    parse the schema.
+
+    :param opts:
+    """
+    # We try to open an encrypted database with the regular u1db
+    # backend should raise a DatabaseError exception.
+    # If the regular backend succeeds, then we need to stop because
+    # the database was not properly initialized.
+    try:
+        sqlite.SQLitePartialExpandDatabase(opts.path)
+    except sqlcipher_dbapi2.DatabaseError:
+        # assert that we can access it using SQLCipher with the given
+        # key
+        dummy_query = ('SELECT count(*) FROM sqlite_master',)
+        return initialize_sqlcipher_db(opts, on_init=dummy_query)
+    else:
+        raise DatabaseIsNotEncrypted()
+
+#
+# Exceptions
+#
+
+
+class DatabaseIsNotEncrypted(Exception):
+    """
+    Exception raised when trying to open non-encrypted databases.
+    """
+    pass
+
+
+def doc_factory(doc_id=None, rev=None, json='{}', has_conflicts=False,
+                syncable=True):
+    """
+    Return a default Soledad Document.
+    Used in the initialization for SQLCipherDatabase
+    """
+    return Document(doc_id=doc_id, rev=rev, json=json,
+                    has_conflicts=has_conflicts, syncable=syncable)
+
+
+sqlite.SQLiteDatabase.register_implementation(SQLCipherDatabase)
+
+
+#
+# twisted.enterprise.adbapi SQLCipher implementation
+#
+
+SQLCIPHER_CONNECTION_TIMEOUT = 10
+
+
+def getConnectionPool(opts, extra_queries=None):
+    openfun = partial(
+        pragmas.set_init_pragmas,
+        opts=opts,
+        extra_queries=extra_queries)
+    return SQLCipherConnectionPool(
+        database=opts.path,
+        check_same_thread=False,
+        cp_openfun=openfun,
+        timeout=SQLCIPHER_CONNECTION_TIMEOUT)
+
+
+class SQLCipherConnection(adbapi.Connection):
+    pass
+
+
+class SQLCipherTransaction(adbapi.Transaction):
+    pass
+
+
+class SQLCipherConnectionPool(adbapi.ConnectionPool):
+
+    connectionFactory = SQLCipherConnection
+    transactionFactory = SQLCipherTransaction
+
+    def __init__(self, *args, **kwargs):
+        adbapi.ConnectionPool.__init__(
+            self, "pysqlcipher.dbapi2", *args, **kwargs)
diff --git a/src/leap/soledad/client/_db/sqlite.py b/src/leap/soledad/client/_db/sqlite.py
new file mode 100644
index 00000000..4f7b1259
--- /dev/null
+++ b/src/leap/soledad/client/_db/sqlite.py
@@ -0,0 +1,930 @@
+# Copyright 2011 Canonical Ltd.
+# Copyright 2016 LEAP Encryption Access Project
+#
+# This file is part of u1db.
+#
+# u1db is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License version 3
+# as published by the Free Software Foundation.
+#
+# u1db is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with u1db.  If not, see <http://www.gnu.org/licenses/>.
+
+"""
+A L2DB implementation that uses SQLite as its persistence layer.
+"""
+
+import errno
+import os
+import json
+import sys
+import time
+import uuid
+import pkg_resources
+
+from sqlite3 import dbapi2
+
+from leap.soledad.common.l2db.backends import CommonBackend, CommonSyncTarget
+from leap.soledad.common.l2db import (
+    Document, errors,
+    query_parser, vectorclock)
+
+
+class SQLiteDatabase(CommonBackend):
+    """A U1DB implementation that uses SQLite as its persistence layer."""
+
+    _sqlite_registry = {}
+
+    def __init__(self, sqlite_file, document_factory=None):
+        """Create a new sqlite file."""
+        self._db_handle = dbapi2.connect(sqlite_file)
+        self._real_replica_uid = None
+        self._ensure_schema()
+        self._factory = document_factory or Document
+
+    def set_document_factory(self, factory):
+        self._factory = factory
+
+    def get_sync_target(self):
+        return SQLiteSyncTarget(self)
+
+    @classmethod
+    def _which_index_storage(cls, c):
+        try:
+            c.execute("SELECT value FROM u1db_config"
+                      " WHERE name = 'index_storage'")
+        except dbapi2.OperationalError as e:
+            # The table does not exist yet
+            return None, e
+        else:
+            return c.fetchone()[0], None
+
+    WAIT_FOR_PARALLEL_INIT_HALF_INTERVAL = 0.5
+
+    @classmethod
+    def _open_database(cls, sqlite_file, document_factory=None):
+        if not os.path.isfile(sqlite_file):
+            raise errors.DatabaseDoesNotExist()
+        tries = 2
+        while True:
+            # Note: There seems to be a bug in sqlite 3.5.9 (with python2.6)
+            #       where without re-opening the database on Windows, it
+            #       doesn't see the transaction that was just committed
+            db_handle = dbapi2.connect(sqlite_file)
+            c = db_handle.cursor()
+            v, err = cls._which_index_storage(c)
+            db_handle.close()
+            if v is not None:
+                break
+            # possibly another process is initializing it, wait for it to be
+            # done
+            if tries == 0:
+                raise err  # go for the richest error?
+            tries -= 1
+            time.sleep(cls.WAIT_FOR_PARALLEL_INIT_HALF_INTERVAL)
+        return SQLiteDatabase._sqlite_registry[v](
+            sqlite_file, document_factory=document_factory)
+
+    @classmethod
+    def open_database(cls, sqlite_file, create, backend_cls=None,
+                      document_factory=None):
+        try:
+            return cls._open_database(
+                sqlite_file, document_factory=document_factory)
+        except errors.DatabaseDoesNotExist:
+            if not create:
+                raise
+            if backend_cls is None:
+                # default is SQLitePartialExpandDatabase
+                backend_cls = SQLitePartialExpandDatabase
+            return backend_cls(sqlite_file, document_factory=document_factory)
+
+    @staticmethod
+    def delete_database(sqlite_file):
+        try:
+            os.unlink(sqlite_file)
+        except OSError as ex:
+            if ex.errno == errno.ENOENT:
+                raise errors.DatabaseDoesNotExist()
+            raise
+
+    @staticmethod
+    def register_implementation(klass):
+        """Register that we implement an SQLiteDatabase.
+
+        The attribute _index_storage_value will be used as the lookup key.
+        """
+        SQLiteDatabase._sqlite_registry[klass._index_storage_value] = klass
+
+    def _get_sqlite_handle(self):
+        """Get access to the underlying sqlite database.
+
+        This should only be used by the test suite, etc, for examining the
+        state of the underlying database.
+        """
+        return self._db_handle
+
+    def _close_sqlite_handle(self):
+        """Release access to the underlying sqlite database."""
+        self._db_handle.close()
+
+    def close(self):
+        self._close_sqlite_handle()
+
+    def _is_initialized(self, c):
+        """Check if this database has been initialized."""
+        c.execute("PRAGMA case_sensitive_like=ON")
+        try:
+            c.execute("SELECT value FROM u1db_config"
+                      " WHERE name = 'sql_schema'")
+        except dbapi2.OperationalError:
+            # The table does not exist yet
+            val = None
+        else:
+            val = c.fetchone()
+        if val is not None:
+            return True
+        return False
+
+    def _initialize(self, c):
+        """Create the schema in the database."""
+        # read the script with sql commands
+        # TODO: Change how we set up the dependency. Most likely use something
+        #   like lp:dirspec to grab the file from a common resource
+        #   directory. Doesn't specifically need to be handled until we get
+        #   to the point of packaging this.
+        schema_content = pkg_resources.resource_string(
+            __name__, 'dbschema.sql')
+        # Note: We'd like to use c.executescript() here, but it seems that
+        #       executescript always commits, even if you set
+        #       isolation_level = None, so if we want to properly handle
+        #       exclusive locking and rollbacks between processes, we need
+        #       to execute it line-by-line
+        for line in schema_content.split(';'):
+            if not line:
+                continue
+            c.execute(line)
+        # add extra fields
+        self._extra_schema_init(c)
+        # A unique identifier should be set for this replica. Implementations
+        # don't have to strictly use uuid here, but we do want the uid to be
+        # unique amongst all databases that will sync with each other.
+        # We might extend this to using something with hostname for easier
+        # debugging.
+        self._set_replica_uid_in_transaction(uuid.uuid4().hex)
+        c.execute("INSERT INTO u1db_config VALUES" " ('index_storage', ?)",
+                  (self._index_storage_value,))
+
+    def _ensure_schema(self):
+        """Ensure that the database schema has been created."""
+        old_isolation_level = self._db_handle.isolation_level
+        c = self._db_handle.cursor()
+        if self._is_initialized(c):
+            return
+        try:
+            # autocommit/own mgmt of transactions
+            self._db_handle.isolation_level = None
+            with self._db_handle:
+                # only one execution path should initialize the db
+                c.execute("begin exclusive")
+                if self._is_initialized(c):
+                    return
+                self._initialize(c)
+        finally:
+            self._db_handle.isolation_level = old_isolation_level
+
+    def _extra_schema_init(self, c):
+        """Add any extra fields, etc to the basic table definitions."""
+
+    def _parse_index_definition(self, index_field):
+        """Parse a field definition for an index, returning a Getter."""
+        # Note: We may want to keep a Parser object around, and cache the
+        #       Getter objects for a greater length of time. Specifically, if
+        #       you create a bunch of indexes, and then insert 50k docs, you'll
+        #       re-parse the indexes between puts. The time to insert the docs
+        #       is still likely to dominate put_doc time, though.
+        parser = query_parser.Parser()
+        getter = parser.parse(index_field)
+        return getter
+
+    def _update_indexes(self, doc_id, raw_doc, getters, db_cursor):
+        """Update document_fields for a single document.
+
+        :param doc_id: Identifier for this document
+        :param raw_doc: The python dict representation of the document.
+        :param getters: A list of [(field_name, Getter)]. Getter.get will be
+            called to evaluate the index definition for this document, and the
+            results will be inserted into the db.
+        :param db_cursor: An sqlite Cursor.
+        :return: None
+        """
+        values = []
+        for field_name, getter in getters:
+            for idx_value in getter.get(raw_doc):
+                values.append((doc_id, field_name, idx_value))
+        if values:
+            db_cursor.executemany(
+                "INSERT INTO document_fields VALUES (?, ?, ?)", values)
+
+    def _set_replica_uid(self, replica_uid):
+        """Force the replica_uid to be set."""
+        with self._db_handle:
+            self._set_replica_uid_in_transaction(replica_uid)
+
+    def _set_replica_uid_in_transaction(self, replica_uid):
+        """Set the replica_uid. A transaction should already be held."""
+        c = self._db_handle.cursor()
+        c.execute("INSERT OR REPLACE INTO u1db_config"
+                  " VALUES ('replica_uid', ?)",
+                  (replica_uid,))
+        self._real_replica_uid = replica_uid
+
+    def _get_replica_uid(self):
+        if self._real_replica_uid is not None:
+            return self._real_replica_uid
+        c = self._db_handle.cursor()
+        c.execute("SELECT value FROM u1db_config WHERE name = 'replica_uid'")
+        val = c.fetchone()
+        if val is None:
+            return None
+        self._real_replica_uid = val[0]
+        return self._real_replica_uid
+
+    _replica_uid = property(_get_replica_uid)
+
+    def _get_generation(self):
+        c = self._db_handle.cursor()
+        c.execute('SELECT max(generation) FROM transaction_log')
+        val = c.fetchone()[0]
+        if val is None:
+            return 0
+        return val
+
+    def _get_generation_info(self):
+        c = self._db_handle.cursor()
+        c.execute(
+            'SELECT max(generation), transaction_id FROM transaction_log ')
+        val = c.fetchone()
+        if val[0] is None:
+            return(0, '')
+        return val
+
+    def _get_trans_id_for_gen(self, generation):
+        if generation == 0:
+            return ''
+        c = self._db_handle.cursor()
+        c.execute(
+            'SELECT transaction_id FROM transaction_log WHERE generation = ?',
+            (generation,))
+        val = c.fetchone()
+        if val is None:
+            raise errors.InvalidGeneration
+        return val[0]
+
+    def _get_transaction_log(self):
+        c = self._db_handle.cursor()
+        c.execute("SELECT doc_id, transaction_id FROM transaction_log"
+                  " ORDER BY generation")
+        return c.fetchall()
+
+    def _get_doc(self, doc_id, check_for_conflicts=False):
+        """Get just the document content, without fancy handling."""
+        c = self._db_handle.cursor()
+        if check_for_conflicts:
+            c.execute(
+                "SELECT document.doc_rev, document.content, "
+                "count(conflicts.doc_rev) FROM document LEFT OUTER JOIN "
+                "conflicts ON conflicts.doc_id = document.doc_id WHERE "
+                "document.doc_id = ? GROUP BY document.doc_id, "
+                "document.doc_rev, document.content;", (doc_id,))
+        else:
+            c.execute(
+                "SELECT doc_rev, content, 0 FROM document WHERE doc_id = ?",
+                (doc_id,))
+        val = c.fetchone()
+        if val is None:
+            return None
+        doc_rev, content, conflicts = val
+        doc = self._factory(doc_id, doc_rev, content)
+        doc.has_conflicts = conflicts > 0
+        return doc
+
+    def _has_conflicts(self, doc_id):
+        c = self._db_handle.cursor()
+        c.execute("SELECT 1 FROM conflicts WHERE doc_id = ? LIMIT 1",
+                  (doc_id,))
+        val = c.fetchone()
+        if val is None:
+            return False
+        else:
+            return True
+
+    def get_doc(self, doc_id, include_deleted=False):
+        doc = self._get_doc(doc_id, check_for_conflicts=True)
+        if doc is None:
+            return None
+        if doc.is_tombstone() and not include_deleted:
+            return None
+        return doc
+
+    def get_all_docs(self, include_deleted=False):
+        """Get all documents from the database."""
+        generation = self._get_generation()
+        results = []
+        c = self._db_handle.cursor()
+        c.execute(
+            "SELECT document.doc_id, document.doc_rev, document.content, "
+            "count(conflicts.doc_rev) FROM document LEFT OUTER JOIN conflicts "
+            "ON conflicts.doc_id = document.doc_id GROUP BY document.doc_id, "
+            "document.doc_rev, document.content;")
+        rows = c.fetchall()
+        for doc_id, doc_rev, content, conflicts in rows:
+            if content is None and not include_deleted:
+                continue
+            doc = self._factory(doc_id, doc_rev, content)
+            doc.has_conflicts = conflicts > 0
+            results.append(doc)
+        return (generation, results)
+
+    def put_doc(self, doc):
+        if doc.doc_id is None:
+            raise errors.InvalidDocId()
+        self._check_doc_id(doc.doc_id)
+        self._check_doc_size(doc)
+        with self._db_handle:
+            old_doc = self._get_doc(doc.doc_id, check_for_conflicts=True)
+            if old_doc and old_doc.has_conflicts:
+                raise errors.ConflictedDoc()
+            if old_doc and doc.rev is None and old_doc.is_tombstone():
+                new_rev = self._allocate_doc_rev(old_doc.rev)
+            else:
+                if old_doc is not None:
+                        if old_doc.rev != doc.rev:
+                            raise errors.RevisionConflict()
+                else:
+                    if doc.rev is not None:
+                        raise errors.RevisionConflict()
+                new_rev = self._allocate_doc_rev(doc.rev)
+            doc.rev = new_rev
+            self._put_and_update_indexes(old_doc, doc)
+        return new_rev
+
+    def _expand_to_fields(self, doc_id, base_field, raw_doc, save_none):
+        """Convert a dict representation into named fields.
+
+        So something like: {'key1': 'val1', 'key2': 'val2'}
+        gets converted into: [(doc_id, 'key1', 'val1', 0)
+                              (doc_id, 'key2', 'val2', 0)]
+        :param doc_id: Just added to every record.
+        :param base_field: if set, these are nested keys, so each field should
+            be appropriately prefixed.
+        :param raw_doc: The python dictionary.
+        """
+        # TODO: Handle lists
+        values = []
+        for field_name, value in raw_doc.iteritems():
+            if value is None and not save_none:
+                continue
+            if base_field:
+                full_name = base_field + '.' + field_name
+            else:
+                full_name = field_name
+            if value is None or isinstance(value, (int, float, basestring)):
+                values.append((doc_id, full_name, value, len(values)))
+            else:
+                subvalues = self._expand_to_fields(doc_id, full_name, value,
+                                                   save_none)
+                for _, subfield_name, val, _ in subvalues:
+                    values.append((doc_id, subfield_name, val, len(values)))
+        return values
+
+    def _put_and_update_indexes(self, old_doc, doc):
+        """Actually insert a document into the database.
+
+        This both updates the existing documents content, and any indexes that
+        refer to this document.
+        """
+        raise NotImplementedError(self._put_and_update_indexes)
+
+    def whats_changed(self, old_generation=0):
+        c = self._db_handle.cursor()
+        c.execute("SELECT generation, doc_id, transaction_id"
+                  " FROM transaction_log"
+                  " WHERE generation > ? ORDER BY generation DESC",
+                  (old_generation,))
+        results = c.fetchall()
+        cur_gen = old_generation
+        seen = set()
+        changes = []
+        newest_trans_id = ''
+        for generation, doc_id, trans_id in results:
+            if doc_id not in seen:
+                changes.append((doc_id, generation, trans_id))
+                seen.add(doc_id)
+        if changes:
+            cur_gen = changes[0][1]  # max generation
+            newest_trans_id = changes[0][2]
+            changes.reverse()
+        else:
+            c.execute("SELECT generation, transaction_id"
+                      " FROM transaction_log ORDER BY generation DESC LIMIT 1")
+            results = c.fetchone()
+            if not results:
+                cur_gen = 0
+                newest_trans_id = ''
+            else:
+                cur_gen, newest_trans_id = results
+
+        return cur_gen, newest_trans_id, changes
+
+    def delete_doc(self, doc):
+        with self._db_handle:
+            old_doc = self._get_doc(doc.doc_id, check_for_conflicts=True)
+            if old_doc is None:
+                raise errors.DocumentDoesNotExist
+            if old_doc.rev != doc.rev:
+                raise errors.RevisionConflict()
+            if old_doc.is_tombstone():
+                raise errors.DocumentAlreadyDeleted
+            if old_doc.has_conflicts:
+                raise errors.ConflictedDoc()
+            new_rev = self._allocate_doc_rev(doc.rev)
+            doc.rev = new_rev
+            doc.make_tombstone()
+            self._put_and_update_indexes(old_doc, doc)
+        return new_rev
+
+    def _get_conflicts(self, doc_id):
+        c = self._db_handle.cursor()
+        c.execute("SELECT doc_rev, content FROM conflicts WHERE doc_id = ?",
+                  (doc_id,))
+        return [self._factory(doc_id, doc_rev, content)
+                for doc_rev, content in c.fetchall()]
+
+    def get_doc_conflicts(self, doc_id):
+        with self._db_handle:
+            conflict_docs = self._get_conflicts(doc_id)
+            if not conflict_docs:
+                return []
+            this_doc = self._get_doc(doc_id)
+            this_doc.has_conflicts = True
+            return [this_doc] + conflict_docs
+
+    def _get_replica_gen_and_trans_id(self, other_replica_uid):
+        c = self._db_handle.cursor()
+        c.execute("SELECT known_generation, known_transaction_id FROM sync_log"
+                  " WHERE replica_uid = ?",
+                  (other_replica_uid,))
+        val = c.fetchone()
+        if val is None:
+            other_gen = 0
+            trans_id = ''
+        else:
+            other_gen = val[0]
+            trans_id = val[1]
+        return other_gen, trans_id
+
+    def _set_replica_gen_and_trans_id(self, other_replica_uid,
+                                      other_generation, other_transaction_id):
+        with self._db_handle:
+            self._do_set_replica_gen_and_trans_id(
+                other_replica_uid, other_generation, other_transaction_id)
+
+    def _do_set_replica_gen_and_trans_id(self, other_replica_uid,
+                                         other_generation,
+                                         other_transaction_id):
+            c = self._db_handle.cursor()
+            c.execute("INSERT OR REPLACE INTO sync_log VALUES (?, ?, ?)",
+                      (other_replica_uid, other_generation,
+                       other_transaction_id))
+
+    def _put_doc_if_newer(self, doc, save_conflict, replica_uid=None,
+                          replica_gen=None, replica_trans_id=None):
+        return super(SQLiteDatabase, self)._put_doc_if_newer(
+            doc,
+            save_conflict=save_conflict,
+            replica_uid=replica_uid, replica_gen=replica_gen,
+            replica_trans_id=replica_trans_id)
+
+    def _add_conflict(self, c, doc_id, my_doc_rev, my_content):
+        c.execute("INSERT INTO conflicts VALUES (?, ?, ?)",
+                  (doc_id, my_doc_rev, my_content))
+
+    def _delete_conflicts(self, c, doc, conflict_revs):
+        deleting = [(doc.doc_id, c_rev) for c_rev in conflict_revs]
+        c.executemany("DELETE FROM conflicts"
+                      " WHERE doc_id=? AND doc_rev=?", deleting)
+        doc.has_conflicts = self._has_conflicts(doc.doc_id)
+
+    def _prune_conflicts(self, doc, doc_vcr):
+        if self._has_conflicts(doc.doc_id):
+            autoresolved = False
+            c_revs_to_prune = []
+            for c_doc in self._get_conflicts(doc.doc_id):
+                c_vcr = vectorclock.VectorClockRev(c_doc.rev)
+                if doc_vcr.is_newer(c_vcr):
+                    c_revs_to_prune.append(c_doc.rev)
+                elif doc.same_content_as(c_doc):
+                    c_revs_to_prune.append(c_doc.rev)
+                    doc_vcr.maximize(c_vcr)
+                    autoresolved = True
+            if autoresolved:
+                doc_vcr.increment(self._replica_uid)
+                doc.rev = doc_vcr.as_str()
+            c = self._db_handle.cursor()
+            self._delete_conflicts(c, doc, c_revs_to_prune)
+
+    def _force_doc_sync_conflict(self, doc):
+        my_doc = self._get_doc(doc.doc_id)
+        c = self._db_handle.cursor()
+        self._prune_conflicts(doc, vectorclock.VectorClockRev(doc.rev))
+        self._add_conflict(c, doc.doc_id, my_doc.rev, my_doc.get_json())
+        doc.has_conflicts = True
+        self._put_and_update_indexes(my_doc, doc)
+
+    def resolve_doc(self, doc, conflicted_doc_revs):
+        with self._db_handle:
+            cur_doc = self._get_doc(doc.doc_id)
+            # TODO: https://bugs.launchpad.net/u1db/+bug/928274
+            #       I think we have a logic bug in resolve_doc
+            #       Specifically, cur_doc.rev is always in the final vector
+            #       clock of revisions that we supersede, even if it wasn't in
+            #       conflicted_doc_revs. We still add it as a conflict, but the
+            #       fact that _put_doc_if_newer propagates resolutions means I
+            #       think that conflict could accidentally be resolved. We need
+            #       to add a test for this case first. (create a rev, create a
+            #       conflict, create another conflict, resolve the first rev
+            #       and first conflict, then make sure that the resolved
+            #       rev doesn't supersede the second conflict rev.) It *might*
+            #       not matter, because the superseding rev is in as a
+            #       conflict, but it does seem incorrect
+            new_rev = self._ensure_maximal_rev(cur_doc.rev,
+                                               conflicted_doc_revs)
+            superseded_revs = set(conflicted_doc_revs)
+            c = self._db_handle.cursor()
+            doc.rev = new_rev
+            if cur_doc.rev in superseded_revs:
+                self._put_and_update_indexes(cur_doc, doc)
+            else:
+                self._add_conflict(c, doc.doc_id, new_rev, doc.get_json())
+            # TODO: Is there some way that we could construct a rev that would
+            #       end up in superseded_revs, such that we add a conflict, and
+            #       then immediately delete it?
+            self._delete_conflicts(c, doc, superseded_revs)
+
+    def list_indexes(self):
+        """Return the list of indexes and their definitions."""
+        c = self._db_handle.cursor()
+        # TODO: How do we test the ordering?
+        c.execute("SELECT name, field FROM index_definitions"
+                  " ORDER BY name, offset")
+        definitions = []
+        cur_name = None
+        for name, field in c.fetchall():
+            if cur_name != name:
+                definitions.append((name, []))
+                cur_name = name
+            definitions[-1][-1].append(field)
+        return definitions
+
+    def _get_index_definition(self, index_name):
+        """Return the stored definition for a given index_name."""
+        c = self._db_handle.cursor()
+        c.execute("SELECT field FROM index_definitions"
+                  " WHERE name = ? ORDER BY offset", (index_name,))
+        fields = [x[0] for x in c.fetchall()]
+        if not fields:
+            raise errors.IndexDoesNotExist
+        return fields
+
+    @staticmethod
+    def _strip_glob(value):
+        """Remove the trailing * from a value."""
+        assert value[-1] == '*'
+        return value[:-1]
+
+    def _format_query(self, definition, key_values):
+        # First, build the definition. We join the document_fields table
+        # against itself, as many times as the 'width' of our definition.
+        # We then do a query for each key_value, one-at-a-time.
+        # Note: All of these strings are static, we could cache them, etc.
+        tables = ["document_fields d%d" % i for i in range(len(definition))]
+        novalue_where = ["d.doc_id = d%d.doc_id"
+                         " AND d%d.field_name = ?"
+                         % (i, i) for i in range(len(definition))]
+        wildcard_where = [novalue_where[i] +
+                          (" AND d%d.value NOT NULL" % (i,))
+                          for i in range(len(definition))]
+        exact_where = [novalue_where[i] +
+                       (" AND d%d.value = ?" % (i,))
+                       for i in range(len(definition))]
+        like_where = [novalue_where[i] +
+                      (" AND d%d.value GLOB ?" % (i,))
+                      for i in range(len(definition))]
+        is_wildcard = False
+        # Merge the lists together, so that:
+        # [field1, field2, field3], [val1, val2, val3]
+        # Becomes:
+        # (field1, val1, field2, val2, field3, val3)
+        args = []
+        where = []
+        for idx, (field, value) in enumerate(zip(definition, key_values)):
+            args.append(field)
+            if value.endswith('*'):
+                if value == '*':
+                    where.append(wildcard_where[idx])
+                else:
+                    # This is a glob match
+                    if is_wildcard:
+                        # We can't have a partial wildcard following
+                        # another wildcard
+                        raise errors.InvalidGlobbing
+                    where.append(like_where[idx])
+                    args.append(value)
+                is_wildcard = True
+            else:
+                if is_wildcard:
+                    raise errors.InvalidGlobbing
+                where.append(exact_where[idx])
+                args.append(value)
+        statement = (
+            "SELECT d.doc_id, d.doc_rev, d.content, count(c.doc_rev) FROM "
+            "document d, %s LEFT OUTER JOIN conflicts c ON c.doc_id = "
+            "d.doc_id WHERE %s GROUP BY d.doc_id, d.doc_rev, d.content ORDER "
+            "BY %s;" % (', '.join(tables), ' AND '.join(where), ', '.join(
+                ['d%d.value' % i for i in range(len(definition))])))
+        return statement, args
+
+    def get_from_index(self, index_name, *key_values):
+        definition = self._get_index_definition(index_name)
+        if len(key_values) != len(definition):
+            raise errors.InvalidValueForIndex()
+        statement, args = self._format_query(definition, key_values)
+        c = self._db_handle.cursor()
+        try:
+            c.execute(statement, tuple(args))
+        except dbapi2.OperationalError as e:
+            raise dbapi2.OperationalError(
+                str(e) +
+                '\nstatement: %s\nargs: %s\n' % (statement, args))
+        res = c.fetchall()
+        results = []
+        for row in res:
+            doc = self._factory(row[0], row[1], row[2])
+            doc.has_conflicts = row[3] > 0
+            results.append(doc)
+        return results
+
+    def _format_range_query(self, definition, start_value, end_value):
+        tables = ["document_fields d%d" % i for i in range(len(definition))]
+        novalue_where = [
+            "d.doc_id = d%d.doc_id AND d%d.field_name = ?" % (i, i) for i in
+            range(len(definition))]
+        wildcard_where = [
+            novalue_where[i] + (" AND d%d.value NOT NULL" % (i,)) for i in
+            range(len(definition))]
+        like_where = [
+            novalue_where[i] + (
+                " AND (d%d.value < ? OR d%d.value GLOB ?)" % (i, i)) for i in
+            range(len(definition))]
+        range_where_lower = [
+            novalue_where[i] + (" AND d%d.value >= ?" % (i,)) for i in
+            range(len(definition))]
+        range_where_upper = [
+            novalue_where[i] + (" AND d%d.value <= ?" % (i,)) for i in
+            range(len(definition))]
+        args = []
+        where = []
+        if start_value:
+            if isinstance(start_value, basestring):
+                start_value = (start_value,)
+            if len(start_value) != len(definition):
+                raise errors.InvalidValueForIndex()
+            is_wildcard = False
+            for idx, (field, value) in enumerate(zip(definition, start_value)):
+                args.append(field)
+                if value.endswith('*'):
+                    if value == '*':
+                        where.append(wildcard_where[idx])
+                    else:
+                        # This is a glob match
+                        if is_wildcard:
+                            # We can't have a partial wildcard following
+                            # another wildcard
+                            raise errors.InvalidGlobbing
+                        where.append(range_where_lower[idx])
+                        args.append(self._strip_glob(value))
+                    is_wildcard = True
+                else:
+                    if is_wildcard:
+                        raise errors.InvalidGlobbing
+                    where.append(range_where_lower[idx])
+                    args.append(value)
+        if end_value:
+            if isinstance(end_value, basestring):
+                end_value = (end_value,)
+            if len(end_value) != len(definition):
+                raise errors.InvalidValueForIndex()
+            is_wildcard = False
+            for idx, (field, value) in enumerate(zip(definition, end_value)):
+                args.append(field)
+                if value.endswith('*'):
+                    if value == '*':
+                        where.append(wildcard_where[idx])
+                    else:
+                        # This is a glob match
+                        if is_wildcard:
+                            # We can't have a partial wildcard following
+                            # another wildcard
+                            raise errors.InvalidGlobbing
+                        where.append(like_where[idx])
+                        args.append(self._strip_glob(value))
+                        args.append(value)
+                    is_wildcard = True
+                else:
+                    if is_wildcard:
+                        raise errors.InvalidGlobbing
+                    where.append(range_where_upper[idx])
+                    args.append(value)
+        statement = (
+            "SELECT d.doc_id, d.doc_rev, d.content, count(c.doc_rev) FROM "
+            "document d, %s LEFT OUTER JOIN conflicts c ON c.doc_id = "
+            "d.doc_id WHERE %s GROUP BY d.doc_id, d.doc_rev, d.content ORDER "
+            "BY %s;" % (', '.join(tables), ' AND '.join(where), ', '.join(
+                ['d%d.value' % i for i in range(len(definition))])))
+        return statement, args
+
+    def get_range_from_index(self, index_name, start_value=None,
+                             end_value=None):
+        """Return all documents with key values in the specified range."""
+        definition = self._get_index_definition(index_name)
+        statement, args = self._format_range_query(
+            definition, start_value, end_value)
+        c = self._db_handle.cursor()
+        try:
+            c.execute(statement, tuple(args))
+        except dbapi2.OperationalError as e:
+            raise dbapi2.OperationalError(
+                str(e) +
+                '\nstatement: %s\nargs: %s\n' % (statement, args))
+        res = c.fetchall()
+        results = []
+        for row in res:
+            doc = self._factory(row[0], row[1], row[2])
+            doc.has_conflicts = row[3] > 0
+            results.append(doc)
+        return results
+
+    def get_index_keys(self, index_name):
+        c = self._db_handle.cursor()
+        definition = self._get_index_definition(index_name)
+        value_fields = ', '.join([
+            'd%d.value' % i for i in range(len(definition))])
+        tables = ["document_fields d%d" % i for i in range(len(definition))]
+        novalue_where = [
+            "d.doc_id = d%d.doc_id AND d%d.field_name = ?" % (i, i) for i in
+            range(len(definition))]
+        where = [
+            novalue_where[i] + (" AND d%d.value NOT NULL" % (i,)) for i in
+            range(len(definition))]
+        statement = (
+            "SELECT %s FROM document d, %s WHERE %s GROUP BY %s;" % (
+                value_fields, ', '.join(tables), ' AND '.join(where),
+                value_fields))
+        try:
+            c.execute(statement, tuple(definition))
+        except dbapi2.OperationalError as e:
+            raise dbapi2.OperationalError(
+                str(e) +
+                '\nstatement: %s\nargs: %s\n' % (statement, tuple(definition)))
+        return c.fetchall()
+
+    def delete_index(self, index_name):
+        with self._db_handle:
+            c = self._db_handle.cursor()
+            c.execute("DELETE FROM index_definitions WHERE name = ?",
+                      (index_name,))
+            c.execute(
+                "DELETE FROM document_fields WHERE document_fields.field_name "
+                " NOT IN (SELECT field from index_definitions)")
+
+
+class SQLiteSyncTarget(CommonSyncTarget):
+
+    def get_sync_info(self, source_replica_uid):
+        source_gen, source_trans_id = self._db._get_replica_gen_and_trans_id(
+            source_replica_uid)
+        my_gen, my_trans_id = self._db._get_generation_info()
+        return (
+            self._db._replica_uid, my_gen, my_trans_id, source_gen,
+            source_trans_id)
+
+    def record_sync_info(self, source_replica_uid, source_replica_generation,
+                         source_replica_transaction_id):
+        if self._trace_hook:
+            self._trace_hook('record_sync_info')
+        self._db._set_replica_gen_and_trans_id(
+            source_replica_uid, source_replica_generation,
+            source_replica_transaction_id)
+
+
+class SQLitePartialExpandDatabase(SQLiteDatabase):
+    """An SQLite Backend that expands documents into a document_field table.
+
+    It stores the original document text in document.doc. For fields that are
+    indexed, the data goes into document_fields.
+    """
+
+    _index_storage_value = 'expand referenced'
+
+    def _get_indexed_fields(self):
+        """Determine what fields are indexed."""
+        c = self._db_handle.cursor()
+        c.execute("SELECT field FROM index_definitions")
+        return set([x[0] for x in c.fetchall()])
+
+    def _evaluate_index(self, raw_doc, field):
+        parser = query_parser.Parser()
+        getter = parser.parse(field)
+        return getter.get(raw_doc)
+
+    def _put_and_update_indexes(self, old_doc, doc):
+        c = self._db_handle.cursor()
+        if doc and not doc.is_tombstone():
+            raw_doc = json.loads(doc.get_json())
+        else:
+            raw_doc = {}
+        if old_doc is not None:
+            c.execute("UPDATE document SET doc_rev=?, content=?"
+                      " WHERE doc_id = ?",
+                      (doc.rev, doc.get_json(), doc.doc_id))
+            c.execute("DELETE FROM document_fields WHERE doc_id = ?",
+                      (doc.doc_id,))
+        else:
+            c.execute("INSERT INTO document (doc_id, doc_rev, content)"
+                      " VALUES (?, ?, ?)",
+                      (doc.doc_id, doc.rev, doc.get_json()))
+        indexed_fields = self._get_indexed_fields()
+        if indexed_fields:
+            # It is expected that len(indexed_fields) is shorter than
+            # len(raw_doc)
+            getters = [(field, self._parse_index_definition(field))
+                       for field in indexed_fields]
+            self._update_indexes(doc.doc_id, raw_doc, getters, c)
+        trans_id = self._allocate_transaction_id()
+        c.execute("INSERT INTO transaction_log(doc_id, transaction_id)"
+                  " VALUES (?, ?)", (doc.doc_id, trans_id))
+
+    def create_index(self, index_name, *index_expressions):
+        with self._db_handle:
+            c = self._db_handle.cursor()
+            cur_fields = self._get_indexed_fields()
+            definition = [(index_name, idx, field)
+                          for idx, field in enumerate(index_expressions)]
+            try:
+                c.executemany("INSERT INTO index_definitions VALUES (?, ?, ?)",
+                              definition)
+            except dbapi2.IntegrityError as e:
+                stored_def = self._get_index_definition(index_name)
+                if stored_def == [x[-1] for x in definition]:
+                    return
+                raise errors.IndexNameTakenError(
+                    str(e) +
+                    str(sys.exc_info()[2])
+                )
+            new_fields = set(
+                [f for f in index_expressions if f not in cur_fields])
+            if new_fields:
+                self._update_all_indexes(new_fields)
+
+    def _iter_all_docs(self):
+        c = self._db_handle.cursor()
+        c.execute("SELECT doc_id, content FROM document")
+        while True:
+            next_rows = c.fetchmany()
+            if not next_rows:
+                break
+            for row in next_rows:
+                yield row
+
+    def _update_all_indexes(self, new_fields):
+        """Iterate all the documents, and add content to document_fields.
+
+        :param new_fields: The index definitions that need to be added.
+        """
+        getters = [(field, self._parse_index_definition(field))
+                   for field in new_fields]
+        c = self._db_handle.cursor()
+        for doc_id, doc in self._iter_all_docs():
+            if doc is None:
+                continue
+            raw_doc = json.loads(doc)
+            self._update_indexes(doc_id, raw_doc, getters, c)
+
+
+SQLiteDatabase.register_implementation(SQLitePartialExpandDatabase)
diff --git a/src/leap/soledad/client/_document.py b/src/leap/soledad/client/_document.py
new file mode 100644
index 00000000..9c8577cb
--- /dev/null
+++ b/src/leap/soledad/client/_document.py
@@ -0,0 +1,254 @@
+# -*- coding: utf-8 -*-
+# _document.py
+# Copyright (C) 2017 LEAP
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+"""
+Public interfaces for adding extra client features to the generic
+SoledadDocument.
+"""
+
+import weakref
+import uuid
+
+from twisted.internet import defer
+
+from zope.interface import Interface
+from zope.interface import implementer
+
+from leap.soledad.common.document import SoledadDocument
+
+
+class IDocumentWithAttachment(Interface):
+    """
+    A document that can have an attachment.
+    """
+
+    def set_store(self, store):
+        """
+        Set the store used by this file to manage attachments.
+
+        :param store: The store used to manage attachments.
+        :type store: Soledad
+        """
+
+    def put_attachment(self, fd):
+        """
+        Attach data to this document.
+
+        Add the attachment to local storage, enqueue for upload.
+
+        The document content will be updated with a pointer to the attachment,
+        but the document has to be manually put in the database to reflect
+        modifications.
+
+        :param fd: A file-like object whose content will be attached to this
+                   document.
+        :type fd: file-like
+
+        :return: A deferred which fires when the attachment has been added to
+                 local storage.
+        :rtype: Deferred
+        """
+
+    def get_attachment(self):
+        """
+        Return the data attached to this document.
+
+        If document content contains a pointer to the attachment, try to get
+        the attachment from local storage and, if not found, from remote
+        storage.
+
+        :return: A deferred which fires with a file like-object whose content
+                 is the attachment of this document, or None if nothing is
+                 attached.
+        :rtype: Deferred
+        """
+
+    def delete_attachment(self):
+        """
+        Delete the attachment of this document.
+
+        The pointer to the attachment will be removed from the document
+        content, but the document has to be manually put in the database to
+        reflect modifications.
+
+        :return: A deferred which fires when the attachment has been deleted
+                 from local storage.
+        :rtype: Deferred
+        """
+
+    def get_attachment_state(self):
+        """
+        Return the state of the attachment of this document.
+
+        The state is a member of AttachmentStates and is of one of NONE,
+        LOCAL, REMOTE or SYNCED.
+
+        :return: A deferred which fires with The state of the attachment of
+                 this document.
+        :rtype: Deferred
+        """
+
+    def is_dirty(self):
+        """
+        Return whether this document's content differs from the contents stored
+        in local database.
+
+        :return: A deferred which fires with True or False, depending on
+                 whether this document is dirty or not.
+        :rtype: Deferred
+        """
+
+    def upload_attachment(self):
+        """
+        Upload this document's attachment.
+
+        :return: A deferred which fires with the state of the attachment after
+                 it's been uploaded, or NONE if there's no attachment for this
+                 document.
+        :rtype: Deferred
+        """
+
+    def download_attachment(self):
+        """
+        Download this document's attachment.
+
+        :return: A deferred which fires with the state of the attachment after
+                 it's been downloaded, or NONE if there's no attachment for
+                 this document.
+        :rtype: Deferred
+        """
+
+
+class BlobDoc(object):
+
+    # TODO probably not needed, but convenient for testing for now.
+
+    def __init__(self, content, blob_id):
+
+        self.blob_id = blob_id
+        self.is_blob = True
+        self.blob_fd = content
+        if blob_id is None:
+            blob_id = uuid.uuid4().get_hex()
+        self.blob_id = blob_id
+
+
+class AttachmentStates(object):
+    NONE = 0
+    LOCAL = 1
+    REMOTE = 2
+    SYNCED = 4
+
+
+@implementer(IDocumentWithAttachment)
+class Document(SoledadDocument):
+
+    def __init__(self, doc_id=None, rev=None, json='{}', has_conflicts=False,
+                 syncable=True, store=None):
+        SoledadDocument.__init__(self, doc_id=doc_id, rev=rev, json=json,
+                                 has_conflicts=has_conflicts,
+                                 syncable=syncable)
+        self.set_store(store)
+
+    #
+    # properties
+    #
+
+    @property
+    def _manager(self):
+        if not self.store or not hasattr(self.store, 'blobmanager'):
+            raise Exception('No blob manager found to manage attachments.')
+        return self.store.blobmanager
+
+    @property
+    def _blob_id(self):
+        if self.content and 'blob_id' in self.content:
+            return self.content['blob_id']
+        return None
+
+    def get_store(self):
+        return self._store() if self._store else None
+
+    def set_store(self, store):
+        self._store = weakref.ref(store) if store else None
+
+    store = property(get_store, set_store)
+
+    #
+    # attachment api
+    #
+
+    def put_attachment(self, fd):
+        # add pointer to content
+        blob_id = self._blob_id or str(uuid.uuid4())
+        if not self.content:
+            self.content = {}
+        self.content['blob_id'] = blob_id
+        # put using manager
+        blob = BlobDoc(fd, blob_id)
+        fd.seek(0, 2)
+        size = fd.tell()
+        fd.seek(0)
+        return self._manager.put(blob, size)
+
+    def get_attachment(self):
+        if not self._blob_id:
+            return defer.succeed(None)
+        return self._manager.get(self._blob_id)
+
+    def delete_attachment(self):
+        raise NotImplementedError
+
+    @defer.inlineCallbacks
+    def get_attachment_state(self):
+        state = AttachmentStates.NONE
+
+        if not self._blob_id:
+            defer.returnValue(state)
+
+        local_list = yield self._manager.local_list()
+        if self._blob_id in local_list:
+            state |= AttachmentStates.LOCAL
+
+        remote_list = yield self._manager.remote_list()
+        if self._blob_id in remote_list:
+            state |= AttachmentStates.REMOTE
+
+        defer.returnValue(state)
+
+    @defer.inlineCallbacks
+    def is_dirty(self):
+        stored = yield self.store.get_doc(self.doc_id)
+        if stored.content != self.content:
+            defer.returnValue(True)
+        defer.returnValue(False)
+
+    @defer.inlineCallbacks
+    def upload_attachment(self):
+        if not self._blob_id:
+            defer.returnValue(AttachmentStates.NONE)
+
+        fd = yield self._manager.get_blob(self._blob_id)
+        # TODO: turn following method into a public one
+        yield self._manager._encrypt_and_upload(self._blob_id, fd)
+        defer.returnValue(self.get_attachment_state())
+
+    @defer.inlineCallbacks
+    def download_attachment(self):
+        if not self._blob_id:
+            defer.returnValue(None)
+        yield self.get_attachment()
+        defer.returnValue(self.get_attachment_state())
diff --git a/src/leap/soledad/client/_http.py b/src/leap/soledad/client/_http.py
new file mode 100644
index 00000000..2a6b9e39
--- /dev/null
+++ b/src/leap/soledad/client/_http.py
@@ -0,0 +1,74 @@
+# -*- coding: utf-8 -*-
+# _http.py
+# Copyright (C) 2017 LEAP
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+"""
+A twisted-based, TLS-pinned, token-authenticated HTTP client.
+"""
+import base64
+
+from twisted.internet import reactor
+from twisted.web.iweb import IAgent
+from twisted.web.client import Agent
+from twisted.web.http_headers import Headers
+
+from treq.client import HTTPClient as _HTTPClient
+
+from zope.interface import implementer
+
+from leap.common.certs import get_compatible_ssl_context_factory
+
+
+__all__ = ['HTTPClient', 'PinnedTokenAgent']
+
+
+class HTTPClient(_HTTPClient):
+
+    def __init__(self, uuid, token, cert_file):
+        self._agent = PinnedTokenAgent(uuid, token, cert_file)
+        super(self.__class__, self).__init__(self._agent)
+
+    def set_token(self, token):
+        self._agent.set_token(token)
+
+
+@implementer(IAgent)
+class PinnedTokenAgent(Agent):
+
+    def __init__(self, uuid, token, cert_file):
+        self._uuid = uuid
+        self._token = None
+        self._creds = None
+        self.set_token(token)
+        # pin this agent with the platform TLS certificate
+        factory = get_compatible_ssl_context_factory(cert_file)
+        Agent.__init__(self, reactor, contextFactory=factory)
+
+    def set_token(self, token):
+        self._token = token
+        self._creds = self._encoded_creds()
+
+    def _encoded_creds(self):
+        creds = '%s:%s' % (self._uuid, self._token)
+        encoded = base64.b64encode(creds)
+        return 'Token %s' % encoded
+
+    def request(self, method, uri, headers=None, bodyProducer=None):
+        # authenticate the request
+        headers = headers or Headers()
+        headers.addRawHeader('Authorization', self._creds)
+        # perform the authenticated request
+        return Agent.request(
+            self, method, uri, headers=headers, bodyProducer=bodyProducer)
diff --git a/src/leap/soledad/client/_pipes.py b/src/leap/soledad/client/_pipes.py
new file mode 100644
index 00000000..eef3f1f9
--- /dev/null
+++ b/src/leap/soledad/client/_pipes.py
@@ -0,0 +1,78 @@
+# -*- coding: utf-8 -*-
+# _pipes.py
+# Copyright (C) 2017 LEAP
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+"""
+Components for piping data on streams.
+"""
+from io import BytesIO
+
+
+__all__ = ['TruncatedTailPipe', 'PreamblePipe']
+
+
+class TruncatedTailPipe(object):
+    """
+    Truncate the last `tail_size` bytes from the stream.
+    """
+
+    def __init__(self, output=None, tail_size=16):
+        self.tail_size = tail_size
+        self.output = output or BytesIO()
+        self.buffer = BytesIO()
+
+    def write(self, data):
+        self.buffer.write(data)
+        if self.buffer.tell() > self.tail_size:
+            self._truncate_tail()
+
+    def _truncate_tail(self):
+        overflow_size = self.buffer.tell() - self.tail_size
+        self.buffer.seek(0)
+        self.output.write(self.buffer.read(overflow_size))
+        remaining = self.buffer.read()
+        self.buffer.seek(0)
+        self.buffer.write(remaining)
+        self.buffer.truncate()
+
+    def close(self):
+        return self.output
+
+
+class PreamblePipe(object):
+    """
+    Consumes data until a space is found, then calls a callback with it and
+    starts forwarding data to consumer returned by this callback.
+    """
+
+    def __init__(self, callback):
+        self.callback = callback
+        self.preamble = BytesIO()
+        self.output = None
+
+    def write(self, data):
+        if not self.output:
+            self._write_preamble(data)
+        else:
+            self.output.write(data)
+
+    def _write_preamble(self, data):
+        if ' ' not in data:
+            self.preamble.write(data)
+            return
+        preamble_chunk, remaining = data.split(' ', 1)
+        self.preamble.write(preamble_chunk)
+        self.output = self.callback(self.preamble)
+        self.output.write(remaining)
diff --git a/src/leap/soledad/client/_recovery_code.py b/src/leap/soledad/client/_recovery_code.py
new file mode 100644
index 00000000..04235a29
--- /dev/null
+++ b/src/leap/soledad/client/_recovery_code.py
@@ -0,0 +1,33 @@
+# -*- coding: utf-8 -*-
+# _recovery_code.py
+# Copyright (C) 2017 LEAP
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+import os
+import binascii
+
+from leap.soledad.common.log import getLogger
+
+logger = getLogger(__name__)
+
+
+class RecoveryCode(object):
+
+    # When we turn this string to hex, it will double in size
+    code_length = 6
+
+    def generate(self):
+        logger.info("generating new recovery code...")
+        return binascii.hexlify(os.urandom(self.code_length))
diff --git a/src/leap/soledad/client/_secrets/__init__.py b/src/leap/soledad/client/_secrets/__init__.py
new file mode 100644
index 00000000..b6c81cda
--- /dev/null
+++ b/src/leap/soledad/client/_secrets/__init__.py
@@ -0,0 +1,129 @@
+# -*- coding: utf-8 -*-
+# _secrets/__init__.py
+# Copyright (C) 2016 LEAP
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+import os
+import scrypt
+
+from leap.soledad.common.log import getLogger
+
+from leap.soledad.client._secrets.storage import SecretsStorage
+from leap.soledad.client._secrets.crypto import SecretsCrypto
+from leap.soledad.client._secrets.util import emit, UserDataMixin
+
+
+logger = getLogger(__name__)
+
+
+class Secrets(UserDataMixin):
+
+    lengths = {
+        'remote_secret': 512,  # remote_secret is used to encrypt remote data.
+        'local_salt': 64,      # local_salt is used in conjunction with
+        'local_secret': 448,   # local_secret to derive a local_key for storage
+    }
+
+    def __init__(self, soledad):
+        self._soledad = soledad
+        self._secrets = {}
+        self.crypto = SecretsCrypto(soledad)
+        self.storage = SecretsStorage(soledad)
+        self._bootstrap()
+
+    #
+    # bootstrap
+    #
+
+    def _bootstrap(self):
+
+        # attempt to load secrets from local storage
+        encrypted = self.storage.load_local()
+        if encrypted:
+            self._secrets = self.crypto.decrypt(encrypted)
+            # maybe update the format of storage of local secret.
+            if encrypted['version'] < self.crypto.VERSION:
+                self.store_secrets()
+            return
+
+        # no secret was found in local storage, so this is a first run of
+        # soledad for this user in this device. It is mandatory that we check
+        # if there's a secret stored in server.
+        encrypted = self.storage.load_remote()
+        if encrypted:
+            self._secrets = self.crypto.decrypt(encrypted)
+            self.store_secrets()
+            return
+
+        # we have *not* found a secret neither in local nor in remote storage,
+        # so we have to generate a new one, and then store it.
+        self._secrets = self._generate()
+        self.store_secrets()
+
+    #
+    # generation
+    #
+
+    @emit('creating')
+    def _generate(self):
+        logger.info("generating new set of secrets...")
+        secrets = {}
+        for name, length in self.lengths.iteritems():
+            secret = os.urandom(length)
+            secrets[name] = secret
+        logger.info("new set of secrets successfully generated")
+        return secrets
+
+    #
+    # crypto
+    #
+
+    def store_secrets(self):
+        # TODO: we have to improve the logic here, as we want to make sure that
+        # whatever is stored locally should only be used after remote storage
+        # is successful. Otherwise, this soledad could start encrypting with a
+        # secret while another soledad in another device could start encrypting
+        # with another secret, which would lead to decryption failures during
+        # sync.
+        encrypted = self.crypto.encrypt(self._secrets)
+        self.storage.save_local(encrypted)
+        self.storage.save_remote(encrypted)
+
+    #
+    # secrets
+    #
+
+    @property
+    def remote_secret(self):
+        return self._secrets.get('remote_secret')
+
+    @property
+    def local_salt(self):
+        return self._secrets.get('local_salt')
+
+    @property
+    def local_secret(self):
+        return self._secrets.get('local_secret')
+
+    @property
+    def local_key(self):
+        # local storage key is scrypt-derived from `local_secret` and
+        # `local_salt` above
+        secret = scrypt.hash(
+            password=self.local_secret,
+            salt=self.local_salt,
+            buflen=32,  # we need a key with 256 bits (32 bytes)
+        )
+        return secret
diff --git a/src/leap/soledad/client/_secrets/crypto.py b/src/leap/soledad/client/_secrets/crypto.py
new file mode 100644
index 00000000..8148151d
--- /dev/null
+++ b/src/leap/soledad/client/_secrets/crypto.py
@@ -0,0 +1,138 @@
+# -*- coding: utf-8 -*-
+# _secrets/crypto.py
+# Copyright (C) 2016 LEAP
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+import binascii
+import json
+import os
+import scrypt
+
+from leap.soledad.common import soledad_assert
+from leap.soledad.common.log import getLogger
+
+from leap.soledad.client._crypto import encrypt_sym, decrypt_sym, ENC_METHOD
+from leap.soledad.client._secrets.util import SecretsError
+
+
+logger = getLogger(__name__)
+
+
+class SecretsCrypto(object):
+
+    VERSION = 2
+
+    def __init__(self, soledad):
+        self._soledad = soledad
+
+    def _get_key(self, salt):
+        passphrase = self._soledad.passphrase.encode('utf8')
+        key = scrypt.hash(passphrase, salt, buflen=32)
+        return key
+
+    #
+    # encryption
+    #
+
+    def encrypt(self, secrets):
+        encoded = {}
+        for name, value in secrets.iteritems():
+            encoded[name] = binascii.b2a_base64(value)
+        plaintext = json.dumps(encoded)
+        salt = os.urandom(64)  # TODO: get salt length from somewhere else
+        key = self._get_key(salt)
+        iv, ciphertext = encrypt_sym(plaintext, key,
+                                     method=ENC_METHOD.aes_256_gcm)
+        encrypted = {
+            'version': self.VERSION,
+            'kdf': 'scrypt',
+            'kdf_salt': binascii.b2a_base64(salt),
+            'kdf_length': len(key),
+            'cipher': ENC_METHOD.aes_256_gcm,
+            'length': len(plaintext),
+            'iv': str(iv),
+            'secrets': binascii.b2a_base64(ciphertext),
+        }
+        return encrypted
+
+    #
+    # decryption
+    #
+
+    def decrypt(self, data):
+        version = data.setdefault('version', 1)
+        method = getattr(self, '_decrypt_v%d' % version)
+        try:
+            return method(data)
+        except Exception as e:
+            logger.error('error decrypting secrets: %r' % e)
+            raise SecretsError(e)
+
+    def _decrypt_v1(self, data):
+        # get encrypted secret from dictionary: the old format allowed for
+        # storage of more than one secret, but this feature was never used and
+        # soledad has been using only one secret so far. As there is a corner
+        # case where the old 'active_secret' key might not be set, we just
+        # ignore it and pop the only secret found in the 'storage_secrets' key.
+        secret_id = data['storage_secrets'].keys().pop()
+        encrypted = data['storage_secrets'][secret_id]
+
+        # assert that we know how to decrypt the secret
+        soledad_assert('cipher' in encrypted)
+        cipher = encrypted['cipher']
+        if cipher == 'aes256':
+            cipher = ENC_METHOD.aes_256_ctr
+        soledad_assert(cipher in ENC_METHOD)
+
+        # decrypt
+        salt = binascii.a2b_base64(encrypted['kdf_salt'])
+        key = self._get_key(salt)
+        separator = ':'
+        iv, ciphertext = encrypted['secret'].split(separator, 1)
+        ciphertext = binascii.a2b_base64(ciphertext)
+        plaintext = self._decrypt(key, iv, ciphertext, encrypted, cipher)
+
+        # create secrets dictionary
+        secrets = {
+            'remote_secret': plaintext[0:512],
+            'local_salt': plaintext[512:576],
+            'local_secret': plaintext[576:1024],
+        }
+        return secrets
+
+    def _decrypt_v2(self, encrypted):
+        cipher = encrypted['cipher']
+        soledad_assert(cipher in ENC_METHOD)
+
+        salt = binascii.a2b_base64(encrypted['kdf_salt'])
+        key = self._get_key(salt)
+        iv = encrypted['iv']
+        ciphertext = binascii.a2b_base64(encrypted['secrets'])
+        plaintext = self._decrypt(
+            key, iv, ciphertext, encrypted, cipher)
+        encoded = json.loads(plaintext)
+        secrets = {}
+        for name, value in encoded.iteritems():
+            secrets[name] = binascii.a2b_base64(value)
+        return secrets
+
+    def _decrypt(self, key, iv, ciphertext, encrypted, method):
+        # assert some properties of the stored secret
+        soledad_assert(encrypted['kdf'] == 'scrypt')
+        soledad_assert(encrypted['kdf_length'] == len(key))
+        # decrypt
+        plaintext = decrypt_sym(ciphertext, key, iv, method)
+        soledad_assert(encrypted['length'] == len(plaintext))
+        return plaintext
diff --git a/src/leap/soledad/client/_secrets/storage.py b/src/leap/soledad/client/_secrets/storage.py
new file mode 100644
index 00000000..85713a48
--- /dev/null
+++ b/src/leap/soledad/client/_secrets/storage.py
@@ -0,0 +1,120 @@
+# -*- coding: utf-8 -*-
+# _secrets/storage.py
+# Copyright (C) 2016 LEAP
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+import json
+import six.moves.urllib.parse as urlparse
+
+from hashlib import sha256
+
+from leap.soledad.common import SHARED_DB_NAME
+from leap.soledad.common.log import getLogger
+
+from leap.soledad.client.shared_db import SoledadSharedDatabase
+from leap.soledad.client._document import Document
+from leap.soledad.client._secrets.util import emit, UserDataMixin
+
+
+logger = getLogger(__name__)
+
+
+class SecretsStorage(UserDataMixin):
+
+    def __init__(self, soledad):
+        self._soledad = soledad
+        self._shared_db = self._soledad.shared_db or self._init_shared_db()
+        self.__remote_doc = None
+
+    @property
+    def _creds(self):
+        uuid = self._soledad.uuid
+        token = self._soledad.token
+        return {'token': {'uuid': uuid, 'token': token}}
+
+    #
+    # local storage
+    #
+
+    def load_local(self):
+        path = self._soledad.secrets_path
+        logger.info("trying to load secrets from disk: %s" % path)
+        try:
+            with open(path, 'r') as f:
+                encrypted = json.loads(f.read())
+            logger.info("secrets loaded successfully from disk")
+            return encrypted
+        except IOError:
+            logger.warn("secrets not found in disk")
+        return None
+
+    def save_local(self, encrypted):
+        path = self._soledad.secrets_path
+        json_data = json.dumps(encrypted)
+        with open(path, 'w') as f:
+            f.write(json_data)
+
+    #
+    # remote storage
+    #
+
+    def _init_shared_db(self):
+        url = urlparse.urljoin(self._soledad.server_url, SHARED_DB_NAME)
+        creds = self._creds
+        db = SoledadSharedDatabase.open_database(url, creds)
+        return db
+
+    def _remote_doc_id(self):
+        passphrase = self._soledad.passphrase.encode('utf8')
+        uuid = self._soledad.uuid
+        text = '%s%s' % (passphrase, uuid)
+        digest = sha256(text).hexdigest()
+        return digest
+
+    @property
+    def _remote_doc(self):
+        if not self.__remote_doc and self._shared_db:
+            doc = self._get_remote_doc()
+            self.__remote_doc = doc
+        return self.__remote_doc
+
+    @emit('downloading')
+    def _get_remote_doc(self):
+        logger.info('trying to load secrets from server...')
+        doc = self._shared_db.get_doc(self._remote_doc_id())
+        if doc:
+            logger.info('secrets loaded successfully from server')
+        else:
+            logger.warn('secrets not found in server')
+        return doc
+
+    def load_remote(self):
+        doc = self._remote_doc
+        if not doc:
+            return None
+        encrypted = doc.content
+        return encrypted
+
+    @emit('uploading')
+    def save_remote(self, encrypted):
+        doc = self._remote_doc
+        if not doc:
+            doc = Document(doc_id=self._remote_doc_id())
+        doc.content = encrypted
+        db = self._shared_db
+        if not db:
+            logger.warn('no shared db found')
+            return
+        db.put_doc(doc)
diff --git a/src/leap/soledad/client/_secrets/util.py b/src/leap/soledad/client/_secrets/util.py
new file mode 100644
index 00000000..6401889b
--- /dev/null
+++ b/src/leap/soledad/client/_secrets/util.py
@@ -0,0 +1,63 @@
+# -*- coding:utf-8 -*-
+# _secrets/util.py
+# Copyright (C) 2016 LEAP
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+
+from leap.soledad.client import events
+
+
+class SecretsError(Exception):
+    pass
+
+
+class UserDataMixin(object):
+    """
+    When emitting an event, we have to pass a dictionary containing user data.
+    This class only defines a property so we don't have to define it in
+    multiple places.
+    """
+
+    @property
+    def _user_data(self):
+        uuid = self._soledad.uuid
+        userid = self._soledad.userid
+        # TODO: seems that uuid and userid hold the same value! We should check
+        # whether we should pass something different or if the events api
+        # really needs two different values.
+        return {'uuid': uuid, 'userid': userid}
+
+
+def emit(verb):
+    def _decorator(method):
+        def _decorated(self, *args, **kwargs):
+
+            # emit starting event
+            user_data = self._user_data
+            name = 'SOLEDAD_' + verb.upper() + '_KEYS'
+            event = getattr(events, name)
+            events.emit_async(event, user_data)
+
+            # run the method
+            result = method(self, *args, **kwargs)
+
+            # emit a finished event
+            name = 'SOLEDAD_DONE_' + verb.upper() + '_KEYS'
+            event = getattr(events, name)
+            events.emit_async(event, user_data)
+
+            return result
+        return _decorated
+    return _decorator
diff --git a/src/leap/soledad/client/api.py b/src/leap/soledad/client/api.py
new file mode 100644
index 00000000..c62b43f0
--- /dev/null
+++ b/src/leap/soledad/client/api.py
@@ -0,0 +1,848 @@
+# -*- coding: utf-8 -*-
+# api.py
+# Copyright (C) 2013, 2014 LEAP
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+"""
+Soledad - Synchronization Of Locally Encrypted Data Among Devices.
+
+This module holds the public api for Soledad.
+
+Soledad is the part of LEAP that manages storage and synchronization of
+application data. It is built on top of U1DB reference Python API and
+implements (1) a SQLCipher backend for local storage in the client, (2) a
+SyncTarget that encrypts data before syncing, and (3) a CouchDB backend for
+remote storage in the server side.
+"""
+import binascii
+import errno
+import os
+import socket
+import ssl
+import uuid
+
+from itertools import chain
+import six.moves.http_client as httplib
+import six.moves.urllib.parse as urlparse
+from six import StringIO
+from collections import defaultdict
+
+from twisted.internet import defer
+from zope.interface import implementer
+
+from leap.common.config import get_path_prefix
+from leap.common.plugins import collect_plugins
+
+from leap.soledad.common import soledad_assert
+from leap.soledad.common import soledad_assert_type
+from leap.soledad.common.log import getLogger
+from leap.soledad.common.l2db.remote import http_client
+from leap.soledad.common.l2db.remote.ssl_match_hostname import match_hostname
+from leap.soledad.common.errors import DatabaseAccessError
+
+from . import events as soledad_events
+from . import interfaces as soledad_interfaces
+from ._crypto import SoledadCrypto
+from ._db import adbapi
+from ._db import blobs
+from ._db import sqlcipher
+from ._recovery_code import RecoveryCode
+from ._secrets import Secrets
+
+
+logger = getLogger(__name__)
+
+
+# we may want to collect statistics from the sync process
+DO_STATS = False
+if os.environ.get('SOLEDAD_STATS'):
+    DO_STATS = True
+
+
+#
+# Constants
+#
+
+"""
+Path to the certificate file used to certify the SSL connection between
+Soledad client and server.
+"""
+SOLEDAD_CERT = None
+
+
+@implementer(soledad_interfaces.ILocalStorage,
+             soledad_interfaces.ISyncableStorage,
+             soledad_interfaces.ISecretsStorage)
+class Soledad(object):
+    """
+    Soledad provides encrypted data storage and sync.
+
+    A Soledad instance is used to store and retrieve data in a local encrypted
+    database and synchronize this database with Soledad server.
+
+    This class is also responsible for bootstrapping users' account by
+    creating cryptographic secrets and/or storing/fetching them on Soledad
+    server.
+    """
+
+    local_db_file_name = 'soledad.u1db'
+    secrets_file_name = "soledad.json"
+    default_prefix = os.path.join(get_path_prefix(), 'leap', 'soledad')
+
+    """
+    A dictionary that holds locks which avoid multiple sync attempts from the
+    same database replica. The dictionary indexes are the paths to each local
+    db, so we guarantee that only one sync happens for a local db at a time.
+    """
+    _sync_lock = defaultdict(defer.DeferredLock)
+
+    def __init__(self, uuid, passphrase, secrets_path, local_db_path,
+                 server_url, cert_file, shared_db=None,
+                 auth_token=None):
+        """
+        Initialize configuration, cryptographic keys and dbs.
+
+        :param uuid: User's uuid.
+        :type uuid: str
+
+        :param passphrase:
+            The passphrase for locking and unlocking encryption secrets for
+            local and remote storage.
+        :type passphrase: unicode
+
+        :param secrets_path:
+            Path for storing encrypted key used for symmetric encryption.
+        :type secrets_path: str
+
+        :param local_db_path: Path for local encrypted storage db.
+        :type local_db_path: str
+
+        :param server_url:
+            URL for Soledad server. This is used either to sync with the user's
+            remote db and to interact with the shared recovery database.
+        :type server_url: str
+
+        :param cert_file:
+            Path to the certificate of the ca used to validate the SSL
+            certificate used by the remote soledad server.
+        :type cert_file: str
+
+        :param shared_db:
+            The shared database.
+        :type shared_db: HTTPDatabase
+
+        :param auth_token:
+            Authorization token for accessing remote databases.
+        :type auth_token: str
+
+        :raise BootstrapSequenceError:
+            Raised when the secret initialization sequence (i.e. retrieval
+            from server or generation and storage on server) has failed for
+            some reason.
+        """
+        # store config params
+        self.uuid = uuid
+        self.passphrase = passphrase
+        self.secrets_path = secrets_path
+        self._local_db_path = local_db_path
+        self.server_url = server_url
+        self.shared_db = shared_db
+        self.token = auth_token
+
+        self._dbsyncer = None
+
+        # configure SSL certificate
+        global SOLEDAD_CERT
+        SOLEDAD_CERT = cert_file
+
+        self._init_config_with_defaults()
+        self._init_working_dirs()
+
+        self._recovery_code = RecoveryCode()
+        self._secrets = Secrets(self)
+        self._crypto = SoledadCrypto(self._secrets.remote_secret)
+        self._init_blobmanager()
+
+        try:
+            # initialize database access, trap any problems so we can shutdown
+            # smoothly.
+            self._init_u1db_sqlcipher_backend()
+            self._init_u1db_syncer()
+        except DatabaseAccessError:
+            # oops! something went wrong with backend initialization. We
+            # have to close any thread-related stuff we have already opened
+            # here, otherwise there might be zombie threads that may clog the
+            # reactor.
+            if hasattr(self, '_dbpool'):
+                self._dbpool.close()
+            raise
+
+    #
+    # initialization/destruction methods
+    #
+
+    def _init_config_with_defaults(self):
+        """
+        Initialize configuration using default values for missing params.
+        """
+        soledad_assert_type(self.passphrase, unicode)
+
+        def initialize(attr, val):
+            return ((getattr(self, attr, None) is None) and
+                    setattr(self, attr, val))
+
+        initialize("_secrets_path", os.path.join(
+            self.default_prefix, self.secrets_file_name))
+        initialize("_local_db_path", os.path.join(
+            self.default_prefix, self.local_db_file_name))
+        # initialize server_url
+        soledad_assert(self.server_url is not None,
+                       'Missing URL for Soledad server.')
+
+    def _init_working_dirs(self):
+        """
+        Create work directories.
+
+        :raise OSError: in case file exists and is not a dir.
+        """
+        paths = map(lambda x: os.path.dirname(x), [
+            self._local_db_path, self._secrets_path])
+        for path in paths:
+            create_path_if_not_exists(path)
+
+    def _init_u1db_sqlcipher_backend(self):
+        """
+        Initialize the U1DB SQLCipher database for local storage.
+
+        Instantiates a modified twisted adbapi that will maintain a threadpool
+        with a u1db-sqclipher connection for each thread, and will return
+        deferreds for each u1db query.
+
+        Currently, Soledad uses the default SQLCipher cipher, i.e.
+        'aes-256-cbc'. We use scrypt to derive a 256-bit encryption key,
+        and internally the SQLCipherDatabase initialization uses the 'raw
+        PRAGMA key' format to handle the key to SQLCipher.
+        """
+        tohex = binascii.b2a_hex
+        # sqlcipher only accepts the hex version
+        key = tohex(self._secrets.local_key)
+
+        opts = sqlcipher.SQLCipherOptions(
+            self._local_db_path, key,
+            is_raw_key=True, create=True)
+        self._sqlcipher_opts = opts
+        self._dbpool = adbapi.getConnectionPool(opts)
+
+    def _init_u1db_syncer(self):
+        """
+        Initialize the U1DB synchronizer.
+        """
+        replica_uid = self._dbpool.replica_uid
+        self._dbsyncer = sqlcipher.SQLCipherU1DBSync(
+            self._sqlcipher_opts, self._crypto, replica_uid,
+            SOLEDAD_CERT)
+
+    def sync_stats(self):
+        sync_phase = 0
+        if getattr(self._dbsyncer, 'sync_phase', None):
+            sync_phase = self._dbsyncer.sync_phase[0]
+        sync_exchange_phase = 0
+        if getattr(self._dbsyncer, 'syncer', None):
+            if getattr(self._dbsyncer.syncer, 'sync_exchange_phase', None):
+                _p = self._dbsyncer.syncer.sync_exchange_phase[0]
+                sync_exchange_phase = _p
+        return sync_phase, sync_exchange_phase
+
+    def _init_blobmanager(self):
+        path = os.path.join(os.path.dirname(self._local_db_path), 'blobs')
+        url = urlparse.urljoin(self.server_url, 'blobs/%s' % uuid)
+        key = self._secrets.local_key
+        self.blobmanager = blobs.BlobManager(path, url, key, self.uuid,
+                                             self.token, SOLEDAD_CERT)
+
+    #
+    # Closing methods
+    #
+
+    def close(self):
+        """
+        Close underlying U1DB database.
+        """
+        logger.debug("closing soledad")
+        self._dbpool.close()
+        self.blobmanager.close()
+        if getattr(self, '_dbsyncer', None):
+            self._dbsyncer.close()
+
+    #
+    # ILocalStorage
+    #
+
+    def _defer(self, meth, *args, **kw):
+        """
+        Defer a method to be run on a U1DB connection pool.
+
+        :param meth: A method to defer to the U1DB connection pool.
+        :type meth: callable
+        :return: A deferred.
+        :rtype: twisted.internet.defer.Deferred
+        """
+        return self._dbpool.runU1DBQuery(meth, *args, **kw)
+
+    def put_doc(self, doc):
+        """
+        Update a document.
+
+        If the document currently has conflicts, put will fail.
+        If the database specifies a maximum document size and the document
+        exceeds it, put will fail and raise a DocumentTooBig exception.
+
+        ============================== WARNING ==============================
+        This method converts the document's contents to unicode in-place. This
+        means that after calling `put_doc(doc)`, the contents of the
+        document, i.e. `doc.content`, might be different from before the
+        call.
+        ============================== WARNING ==============================
+
+        :param doc: A document with new content.
+        :type doc: leap.soledad.common.document.Document
+        :return: A deferred whose callback will be invoked with the new
+            revision identifier for the document. The document object will
+            also be updated.
+        :rtype: twisted.internet.defer.Deferred
+        """
+        d = self._defer("put_doc", doc)
+        return d
+
+    def delete_doc(self, doc):
+        """
+        Mark a document as deleted.
+
+        Will abort if the current revision doesn't match doc.rev.
+        This will also set doc.content to None.
+
+        :param doc: A document to be deleted.
+        :type doc: leap.soledad.common.document.Document
+        :return: A deferred.
+        :rtype: twisted.internet.defer.Deferred
+        """
+        soledad_assert(doc is not None, "delete_doc doesn't accept None.")
+        return self._defer("delete_doc", doc)
+
+    def get_doc(self, doc_id, include_deleted=False):
+        """
+        Get the JSON string for the given document.
+
+        :param doc_id: The unique document identifier
+        :type doc_id: str
+        :param include_deleted: If set to True, deleted documents will be
+            returned with empty content. Otherwise asking for a deleted
+            document will return None.
+        :type include_deleted: bool
+        :return: A deferred whose callback will be invoked with a document
+            object.
+        :rtype: twisted.internet.defer.Deferred
+        """
+        return self._defer(
+            "get_doc", doc_id, include_deleted=include_deleted)
+
+    def get_docs(
+            self, doc_ids, check_for_conflicts=True, include_deleted=False):
+        """
+        Get the JSON content for many documents.
+
+        :param doc_ids: A list of document identifiers.
+        :type doc_ids: list
+        :param check_for_conflicts: If set to False, then the conflict check
+            will be skipped, and 'None' will be returned instead of True/False.
+        :type check_for_conflicts: bool
+        :param include_deleted: If set to True, deleted documents will be
+            returned with empty content. Otherwise deleted documents will not
+            be included in the results.
+        :type include_deleted: bool
+        :return: A deferred whose callback will be invoked with an iterable
+            giving the document object for each document id in matching
+            doc_ids order.
+        :rtype: twisted.internet.defer.Deferred
+        """
+        return self._defer(
+            "get_docs", doc_ids, check_for_conflicts=check_for_conflicts,
+            include_deleted=include_deleted)
+
+    def get_all_docs(self, include_deleted=False):
+        """
+        Get the JSON content for all documents in the database.
+
+        :param include_deleted: If set to True, deleted documents will be
+            returned with empty content. Otherwise deleted documents will not
+            be included in the results.
+        :type include_deleted: bool
+
+        :return: A deferred which, when fired, will pass the a tuple
+            containing (generation, [Document]) to the callback, with the
+            current generation of the database, followed by a list of all the
+            documents in the database.
+        :rtype: twisted.internet.defer.Deferred
+        """
+        return self._defer("get_all_docs", include_deleted)
+
+    @defer.inlineCallbacks
+    def create_doc(self, content, doc_id=None):
+        """
+        Create a new document.
+
+        You can optionally specify the document identifier, but the document
+        must not already exist. See 'put_doc' if you want to override an
+        existing document.
+        If the database specifies a maximum document size and the document
+        exceeds it, create will fail and raise a DocumentTooBig exception.
+
+        :param content: A Python dictionary.
+        :type content: dict
+        :param doc_id: An optional identifier specifying the document id.
+        :type doc_id: str
+        :return: A deferred whose callback will be invoked with a document.
+        :rtype: twisted.internet.defer.Deferred
+        """
+        # TODO we probably should pass an optional "encoding" parameter to
+        # create_doc (and probably to put_doc too). There are cases (mail
+        # payloads for example) in which we already have the encoding in the
+        # headers, so we don't need to guess it.
+        doc = yield self._defer("create_doc", content, doc_id=doc_id)
+        doc.set_store(self)
+        defer.returnValue(doc)
+
+    def create_doc_from_json(self, json, doc_id=None):
+        """
+        Create a new document.
+
+        You can optionally specify the document identifier, but the document
+        must not already exist. See 'put_doc' if you want to override an
+        existing document.
+        If the database specifies a maximum document size and the document
+        exceeds it, create will fail and raise a DocumentTooBig exception.
+
+        :param json: The JSON document string
+        :type json: dict
+        :param doc_id: An optional identifier specifying the document id.
+        :type doc_id: str
+        :return: A deferred whose callback will be invoked with a document.
+        :rtype: twisted.internet.defer.Deferred
+        """
+        return self._defer("create_doc_from_json", json, doc_id=doc_id)
+
+    def create_index(self, index_name, *index_expressions):
+        """
+        Create a named index, which can then be queried for future lookups.
+
+        Creating an index which already exists is not an error, and is cheap.
+        Creating an index which does not match the index_expressions of the
+        existing index is an error.
+        Creating an index will block until the expressions have been evaluated
+        and the index generated.
+
+        :param index_name: A unique name which can be used as a key prefix
+        :type index_name: str
+        :param index_expressions: index expressions defining the index
+            information.
+
+            Examples:
+
+            "fieldname", or "fieldname.subfieldname" to index alphabetically
+            sorted on the contents of a field.
+
+            "number(fieldname, width)", "lower(fieldname)"
+        :type index_expresions: list of str
+        :return: A deferred.
+        :rtype: twisted.internet.defer.Deferred
+        """
+        return self._defer("create_index", index_name, *index_expressions)
+
+    def delete_index(self, index_name):
+        """
+        Remove a named index.
+
+        :param index_name: The name of the index we are removing
+        :type index_name: str
+        :return: A deferred.
+        :rtype: twisted.internet.defer.Deferred
+        """
+        return self._defer("delete_index", index_name)
+
+    def list_indexes(self):
+        """
+        List the definitions of all known indexes.
+
+        :return: A deferred whose callback will be invoked with a list of
+            [('index-name', ['field', 'field2'])] definitions.
+        :rtype: twisted.internet.defer.Deferred
+        """
+        return self._defer("list_indexes")
+
+    def get_from_index(self, index_name, *key_values):
+        """
+        Return documents that match the keys supplied.
+
+        You must supply exactly the same number of values as have been defined
+        in the index. It is possible to do a prefix match by using '*' to
+        indicate a wildcard match. You can only supply '*' to trailing entries,
+        (eg 'val', '*', '*' is allowed, but '*', 'val', 'val' is not.)
+        It is also possible to append a '*' to the last supplied value (eg
+        'val*', '*', '*' or 'val', 'val*', '*', but not 'val*', 'val', '*')
+
+        :param index_name: The index to query
+        :type index_name: str
+        :param key_values: values to match. eg, if you have
+            an index with 3 fields then you would have:
+            get_from_index(index_name, val1, val2, val3)
+        :type key_values: list
+        :return: A deferred whose callback will be invoked with a list of
+            [Document].
+        :rtype: twisted.internet.defer.Deferred
+        """
+        return self._defer("get_from_index", index_name, *key_values)
+
+    def get_count_from_index(self, index_name, *key_values):
+        """
+        Return the count for a given combination of index_name
+        and key values.
+
+        Extension method made from similar methods in u1db version 13.09
+
+        :param index_name: The index to query
+        :type index_name: str
+        :param key_values: values to match. eg, if you have
+                           an index with 3 fields then you would have:
+                           get_from_index(index_name, val1, val2, val3)
+        :type key_values: tuple
+        :return: A deferred whose callback will be invoked with the count.
+        :rtype: twisted.internet.defer.Deferred
+        """
+        return self._defer("get_count_from_index", index_name, *key_values)
+
+    def get_range_from_index(self, index_name, start_value, end_value):
+        """
+        Return documents that fall within the specified range.
+
+        Both ends of the range are inclusive. For both start_value and
+        end_value, one must supply exactly the same number of values as have
+        been defined in the index, or pass None. In case of a single column
+        index, a string is accepted as an alternative for a tuple with a single
+        value. It is possible to do a prefix match by using '*' to indicate
+        a wildcard match. You can only supply '*' to trailing entries, (eg
+        'val', '*', '*' is allowed, but '*', 'val', 'val' is not.) It is also
+        possible to append a '*' to the last supplied value (eg 'val*', '*',
+        '*' or 'val', 'val*', '*', but not 'val*', 'val', '*')
+
+        :param index_name: The index to query
+        :type index_name: str
+        :param start_values: tuples of values that define the lower bound of
+            the range. eg, if you have an index with 3 fields then you would
+            have: (val1, val2, val3)
+        :type start_values: tuple
+        :param end_values: tuples of values that define the upper bound of the
+            range. eg, if you have an index with 3 fields then you would have:
+            (val1, val2, val3)
+        :type end_values: tuple
+        :return: A deferred whose callback will be invoked with a list of
+            [Document].
+        :rtype: twisted.internet.defer.Deferred
+        """
+
+        return self._defer(
+            "get_range_from_index", index_name, start_value, end_value)
+
+    def get_index_keys(self, index_name):
+        """
+        Return all keys under which documents are indexed in this index.
+
+        :param index_name: The index to query
+        :type index_name: str
+        :return: A deferred whose callback will be invoked with a list of
+            tuples of indexed keys.
+        :rtype: twisted.internet.defer.Deferred
+        """
+        return self._defer("get_index_keys", index_name)
+
+    def get_doc_conflicts(self, doc_id):
+        """
+        Get the list of conflicts for the given document.
+
+        The order of the conflicts is such that the first entry is the value
+        that would be returned by "get_doc".
+
+        :param doc_id: The unique document identifier
+        :type doc_id: str
+        :return: A deferred whose callback will be invoked with a list of the
+            Document entries that are conflicted.
+        :rtype: twisted.internet.defer.Deferred
+        """
+        return self._defer("get_doc_conflicts", doc_id)
+
+    def resolve_doc(self, doc, conflicted_doc_revs):
+        """
+        Mark a document as no longer conflicted.
+
+        We take the list of revisions that the client knows about that it is
+        superseding. This may be a different list from the actual current
+        conflicts, in which case only those are removed as conflicted.  This
+        may fail if the conflict list is significantly different from the
+        supplied information. (sync could have happened in the background from
+        the time you GET_DOC_CONFLICTS until the point where you RESOLVE)
+
+        :param doc: A Document with the new content to be inserted.
+        :type doc: Document
+        :param conflicted_doc_revs: A list of revisions that the new content
+            supersedes.
+        :type conflicted_doc_revs: list(str)
+        :return: A deferred.
+        :rtype: twisted.internet.defer.Deferred
+        """
+        return self._defer("resolve_doc", doc, conflicted_doc_revs)
+
+    @property
+    def local_db_path(self):
+        return self._local_db_path
+
+    @property
+    def userid(self):
+        return self.uuid
+
+    #
+    # ISyncableStorage
+    #
+
+    def sync(self):
+        """
+        Synchronize documents with the server replica.
+
+        This method uses a lock to prevent multiple concurrent sync processes
+        over the same local db file.
+
+        :return: A deferred lock that will run the actual sync process when
+                 the lock is acquired, and which will fire with with the local
+                 generation before the synchronization was performed.
+        :rtype: twisted.internet.defer.Deferred
+        """
+        # maybe bypass sync
+        # TODO: That's because bitmask may not provide us a token, but
+        # this should be handled on the caller side. Here, calling us without
+        # a token is a real error.
+        if not self.token:
+            generation = self._dbsyncer.get_generation()
+            return defer.succeed(generation)
+
+        d = self.sync_lock.run(
+            self._sync)
+        return d
+
+    def _sync(self):
+        """
+        Synchronize documents with the server replica.
+
+        :return: A deferred whose callback will be invoked with the local
+            generation before the synchronization was performed.
+        :rtype: twisted.internet.defer.Deferred
+        """
+        sync_url = urlparse.urljoin(self.server_url, 'user-%s' % self.uuid)
+        if not self._dbsyncer:
+            return
+        creds = {'token': {'uuid': self.uuid, 'token': self.token}}
+        d = self._dbsyncer.sync(sync_url, creds=creds)
+
+        def _sync_callback(local_gen):
+            self._last_received_docs = docs = self._dbsyncer.received_docs
+
+            # Post-Sync Hooks
+            if docs:
+                iface = soledad_interfaces.ISoledadPostSyncPlugin
+                suitable_plugins = collect_plugins(iface)
+                for plugin in suitable_plugins:
+                    watched = plugin.watched_doc_types
+                    r = [filter(
+                        lambda s: s.startswith(preffix),
+                        docs) for preffix in watched]
+                    filtered = list(chain(*r))
+                    plugin.process_received_docs(filtered)
+
+            return local_gen
+
+        def _sync_errback(failure):
+            s = StringIO()
+            failure.printDetailedTraceback(file=s)
+            msg = "got exception when syncing!\n" + s.getvalue()
+            logger.error(msg)
+            return failure
+
+        def _emit_done_data_sync(passthrough):
+            user_data = {'uuid': self.uuid, 'userid': self.userid}
+            soledad_events.emit_async(
+                soledad_events.SOLEDAD_DONE_DATA_SYNC, user_data)
+            return passthrough
+
+        d.addCallbacks(_sync_callback, _sync_errback)
+        d.addCallback(_emit_done_data_sync)
+        return d
+
+    @property
+    def sync_lock(self):
+        """
+        Class based lock to prevent concurrent syncs using the same local db
+        file.
+
+        :return: A shared lock based on this instance's db file path.
+        :rtype: DeferredLock
+        """
+        return self._sync_lock[self._local_db_path]
+
+    @property
+    def syncing(self):
+        """
+        Return wether Soledad is currently synchronizing with the server.
+
+        :return: Wether Soledad is currently synchronizing with the server.
+        :rtype: bool
+        """
+        return self.sync_lock.locked
+
+    #
+    # ISecretsStorage
+    #
+
+    @property
+    def secrets(self):
+        """
+        Return the secrets object.
+
+        :return: The secrets object.
+        :rtype: Secrets
+        """
+        return self._secrets
+
+    def change_passphrase(self, new_passphrase):
+        """
+        Change the passphrase that encrypts the storage secret.
+
+        :param new_passphrase: The new passphrase.
+        :type new_passphrase: unicode
+
+        :raise NoStorageSecret: Raised if there's no storage secret available.
+        """
+        self.passphrase = new_passphrase
+        self._secrets.store_secrets()
+
+    #
+    # Raw SQLCIPHER Queries
+    #
+
+    def raw_sqlcipher_query(self, *args, **kw):
+        """
+        Run a raw sqlcipher query in the local database, and return a deferred
+        that will be fired with the result.
+        """
+        return self._dbpool.runQuery(*args, **kw)
+
+    def raw_sqlcipher_operation(self, *args, **kw):
+        """
+        Run a raw sqlcipher operation in the local database, and return a
+        deferred that will be fired with None.
+        """
+        return self._dbpool.runOperation(*args, **kw)
+
+    #
+    # Service authentication
+    #
+
+    @defer.inlineCallbacks
+    def get_or_create_service_token(self, service):
+        """
+        Return the stored token for a given service, or generates and stores a
+        random one if it does not exist.
+
+        These tokens can be used to authenticate services.
+        """
+        # FIXME this could use the local sqlcipher database, to avoid
+        # problems with different replicas creating different tokens.
+
+        yield self.create_index('by-servicetoken', 'type', 'service')
+        docs = yield self._get_token_for_service(service)
+        if docs:
+            doc = docs[0]
+            defer.returnValue(doc.content['token'])
+        else:
+            token = str(uuid.uuid4()).replace('-', '')[-24:]
+            yield self._set_token_for_service(service, token)
+            defer.returnValue(token)
+
+    def _get_token_for_service(self, service):
+        return self.get_from_index('by-servicetoken', 'servicetoken', service)
+
+    def _set_token_for_service(self, service, token):
+        doc = {'type': 'servicetoken', 'service': service, 'token': token}
+        return self.create_doc(doc)
+
+    def create_recovery_code(self):
+        return self._recovery_code.generate()
+
+
+def create_path_if_not_exists(path):
+    try:
+        if not os.path.isdir(path):
+            logger.info('creating directory: %s.' % path)
+        os.makedirs(path)
+    except OSError as exc:
+        if exc.errno == errno.EEXIST and os.path.isdir(path):
+            pass
+        else:
+            raise
+
+# ----------------------------------------------------------------------------
+# Monkey patching u1db to be able to provide a custom SSL cert
+# ----------------------------------------------------------------------------
+
+
+# We need a more reasonable timeout (in seconds)
+SOLEDAD_TIMEOUT = 120
+
+
+class VerifiedHTTPSConnection(httplib.HTTPSConnection):
+    """
+    HTTPSConnection verifying server side certificates.
+    """
+    # derived from httplib.py
+
+    def connect(self):
+        """
+        Connect to a host on a given (SSL) port.
+        """
+        try:
+            source = self.source_address
+            sock = socket.create_connection((self.host, self.port),
+                                            SOLEDAD_TIMEOUT, source)
+        except AttributeError:
+            # source_address was introduced in 2.7
+            sock = socket.create_connection((self.host, self.port),
+                                            SOLEDAD_TIMEOUT)
+        if self._tunnel_host:
+            self.sock = sock
+            self._tunnel()
+
+        self.sock = ssl.wrap_socket(sock,
+                                    ca_certs=SOLEDAD_CERT,
+                                    cert_reqs=ssl.CERT_REQUIRED)
+        match_hostname(self.sock.getpeercert(), self.host)
+
+
+old__VerifiedHTTPSConnection = http_client._VerifiedHTTPSConnection
+http_client._VerifiedHTTPSConnection = VerifiedHTTPSConnection
diff --git a/src/leap/soledad/client/auth.py b/src/leap/soledad/client/auth.py
new file mode 100644
index 00000000..78e9bf1b
--- /dev/null
+++ b/src/leap/soledad/client/auth.py
@@ -0,0 +1,69 @@
+# -*- coding: utf-8 -*-
+# auth.py
+# Copyright (C) 2013 LEAP
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+"""
+Methods for token-based authentication.
+
+These methods have to be included in all classes that extend HTTPClient so
+they can do token-based auth requests to the Soledad server.
+"""
+import base64
+
+from leap.soledad.common.l2db import errors
+
+
+class TokenBasedAuth(object):
+    """
+    Encapsulate token-auth methods for classes that inherit from
+    u1db.remote.http_client.HTTPClient.
+    """
+
+    def set_token_credentials(self, uuid, token):
+        """
+        Store given credentials so we can sign the request later.
+
+        :param uuid: The user's uuid.
+        :type uuid: str
+        :param token: The authentication token.
+        :type token: str
+        """
+        self._creds = {'token': (uuid, token)}
+
+    def _sign_request(self, method, url_query, params):
+        """
+        Return an authorization header to be included in the HTTP request, in
+        the form:
+
+            [('Authorization', 'Token <(base64 encoded) uuid:token>')]
+
+        :param method: The HTTP method.
+        :type method: str
+        :param url_query: The URL query string.
+        :type url_query: str
+        :param params: A list with encoded query parameters.
+        :type param: list
+
+        :return: The Authorization header.
+        :rtype: list of tuple
+        """
+        if 'token' in self._creds:
+            uuid, token = self._creds['token']
+            auth = '%s:%s' % (uuid, token)
+            b64_token = base64.b64encode(auth)
+            return [('Authorization', 'Token %s' % b64_token)]
+        else:
+            raise errors.UnknownAuthMethod(
+                'Wrong credentials: %s' % self._creds)
diff --git a/src/leap/soledad/client/crypto.py b/src/leap/soledad/client/crypto.py
new file mode 100644
index 00000000..0f19c964
--- /dev/null
+++ b/src/leap/soledad/client/crypto.py
@@ -0,0 +1,448 @@
+# -*- coding: utf-8 -*-
+# crypto.py
+# Copyright (C) 2013, 2014 LEAP
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+"""
+Cryptographic utilities for Soledad.
+"""
+import os
+import binascii
+import hmac
+import hashlib
+import json
+
+from cryptography.hazmat.backends import default_backend
+from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
+
+from leap.soledad.common import soledad_assert
+from leap.soledad.common import soledad_assert_type
+from leap.soledad.common import crypto
+from leap.soledad.common.log import getLogger
+import warnings
+
+
+logger = getLogger(__name__)
+warnings.warn("'soledad.client.crypto' MODULE DEPRECATED",
+              DeprecationWarning, stacklevel=2)
+
+
+MAC_KEY_LENGTH = 64
+
+crypto_backend = default_backend()
+
+
+def encrypt_sym(data, key):
+    """
+    Encrypt data using AES-256 cipher in CTR mode.
+
+    :param data: The data to be encrypted.
+    :type data: str
+    :param key: The key used to encrypt data (must be 256 bits long).
+    :type key: str
+
+    :return: A tuple with the initialization vector and the encrypted data.
+    :rtype: (long, str)
+    """
+    soledad_assert_type(key, str)
+    soledad_assert(
+        len(key) == 32,  # 32 x 8 = 256 bits.
+        'Wrong key size: %s bits (must be 256 bits long).' %
+        (len(key) * 8))
+
+    iv = os.urandom(16)
+    cipher = Cipher(algorithms.AES(key), modes.CTR(iv), backend=crypto_backend)
+    encryptor = cipher.encryptor()
+    ciphertext = encryptor.update(data) + encryptor.finalize()
+
+    return binascii.b2a_base64(iv), ciphertext
+
+
+def decrypt_sym(data, key, iv):
+    """
+    Decrypt some data previously encrypted using AES-256 cipher in CTR mode.
+
+    :param data: The data to be decrypted.
+    :type data: str
+    :param key: The symmetric key used to decrypt data (must be 256 bits
+                long).
+    :type key: str
+    :param iv: The initialization vector.
+    :type iv: long
+
+    :return: The decrypted data.
+    :rtype: str
+    """
+    soledad_assert_type(key, str)
+    # assert params
+    soledad_assert(
+        len(key) == 32,  # 32 x 8 = 256 bits.
+        'Wrong key size: %s (must be 256 bits long).' % len(key))
+    iv = binascii.a2b_base64(iv)
+    cipher = Cipher(algorithms.AES(key), modes.CTR(iv), backend=crypto_backend)
+    decryptor = cipher.decryptor()
+    return decryptor.update(data) + decryptor.finalize()
+
+
+def doc_mac_key(doc_id, secret):
+    """
+    Generate a key for calculating a MAC for a document whose id is
+    C{doc_id}.
+
+    The key is derived using HMAC having sha256 as underlying hash
+    function. The key used for HMAC is the first MAC_KEY_LENGTH characters
+    of Soledad's storage secret. The HMAC message is C{doc_id}.
+
+    :param doc_id: The id of the document.
+    :type doc_id: str
+
+    :param secret: The Soledad storage secret
+    :type secret: str
+
+    :return: The key.
+    :rtype: str
+    """
+    soledad_assert(secret is not None)
+    return hmac.new(
+        secret[:MAC_KEY_LENGTH],
+        doc_id,
+        hashlib.sha256).digest()
+
+
+class SoledadCrypto(object):
+    """
+    General cryptographic functionality encapsulated in a
+    object that can be passed along.
+    """
+    def __init__(self, secret):
+        """
+        Initialize the crypto object.
+
+        :param secret: The Soledad remote storage secret.
+        :type secret: str
+        """
+        self._secret = secret
+
+    def doc_mac_key(self, doc_id):
+        return doc_mac_key(doc_id, self._secret)
+
+    def doc_passphrase(self, doc_id):
+        """
+        Generate a passphrase for symmetric encryption of document's contents.
+
+        The password is derived using HMAC having sha256 as underlying hash
+        function. The key used for HMAC are the first
+        C{soledad.REMOTE_STORAGE_SECRET_LENGTH} bytes of Soledad's storage
+        secret stripped from the first MAC_KEY_LENGTH characters. The HMAC
+        message is C{doc_id}.
+
+        :param doc_id: The id of the document that will be encrypted using
+            this passphrase.
+        :type doc_id: str
+
+        :return: The passphrase.
+        :rtype: str
+        """
+        soledad_assert(self._secret is not None)
+        return hmac.new(
+            self._secret[MAC_KEY_LENGTH:],
+            doc_id,
+            hashlib.sha256).digest()
+
+    def encrypt_doc(self, doc):
+        """
+        Wrapper around encrypt_docstr that accepts the document as argument.
+
+        :param doc: the document.
+        :type doc: Document
+        """
+        key = self.doc_passphrase(doc.doc_id)
+
+        return encrypt_docstr(
+            doc.get_json(), doc.doc_id, doc.rev, key, self._secret)
+
+    def decrypt_doc(self, doc):
+        """
+        Wrapper around decrypt_doc_dict that accepts the document as argument.
+
+        :param doc: the document.
+        :type doc: Document
+
+        :return: json string with the decrypted document
+        :rtype: str
+        """
+        key = self.doc_passphrase(doc.doc_id)
+        return decrypt_doc_dict(
+            doc.content, doc.doc_id, doc.rev, key, self._secret)
+
+    @property
+    def secret(self):
+        return self._secret
+
+
+#
+# Crypto utilities for a Document.
+#
+
+def mac_doc(doc_id, doc_rev, ciphertext, enc_scheme, enc_method, enc_iv,
+            mac_method, secret):
+    """
+    Calculate a MAC for C{doc} using C{ciphertext}.
+
+    Current MAC method used is HMAC, with the following parameters:
+
+        * key: sha256(storage_secret, doc_id)
+        * msg: doc_id + doc_rev + ciphertext
+        * digestmod: sha256
+
+    :param doc_id: The id of the document.
+    :type doc_id: str
+    :param doc_rev: The revision of the document.
+    :type doc_rev: str
+    :param ciphertext: The content of the document.
+    :type ciphertext: str
+    :param enc_scheme: The encryption scheme.
+    :type enc_scheme: str
+    :param enc_method: The encryption method.
+    :type enc_method: str
+    :param enc_iv: The encryption initialization vector.
+    :type enc_iv: str
+    :param mac_method: The MAC method to use.
+    :type mac_method: str
+    :param secret: The Soledad storage secret
+    :type secret: str
+
+    :return: The calculated MAC.
+    :rtype: str
+
+    :raise crypto.UnknownMacMethodError: Raised when C{mac_method} is unknown.
+    """
+    try:
+        soledad_assert(mac_method == crypto.MacMethods.HMAC)
+    except AssertionError:
+        raise crypto.UnknownMacMethodError
+    template = "{doc_id}{doc_rev}{ciphertext}{enc_scheme}{enc_method}{enc_iv}"
+    content = template.format(
+        doc_id=doc_id,
+        doc_rev=doc_rev,
+        ciphertext=ciphertext,
+        enc_scheme=enc_scheme,
+        enc_method=enc_method,
+        enc_iv=enc_iv)
+    return hmac.new(
+        doc_mac_key(doc_id, secret),
+        content,
+        hashlib.sha256).digest()
+
+
+def encrypt_docstr(docstr, doc_id, doc_rev, key, secret):
+    """
+    Encrypt C{doc}'s content.
+
+    Encrypt doc's contents using AES-256 CTR mode and return a valid JSON
+    string representing the following:
+
+        {
+            crypto.ENC_JSON_KEY: '<encrypted doc JSON string>',
+            crypto.ENC_SCHEME_KEY: 'symkey',
+            crypto.ENC_METHOD_KEY: crypto.EncryptionMethods.AES_256_CTR,
+            crypto.ENC_IV_KEY: '<the initial value used to encrypt>',
+            MAC_KEY: '<mac>'
+            crypto.MAC_METHOD_KEY: 'hmac'
+        }
+
+    :param docstr: A representation of the document to be encrypted.
+    :type docstr: str or unicode.
+
+    :param doc_id: The document id.
+    :type doc_id: str
+
+    :param doc_rev: The document revision.
+    :type doc_rev: str
+
+    :param key: The key used to encrypt ``data`` (must be 256 bits long).
+    :type key: str
+
+    :param secret: The Soledad storage secret (used for MAC auth).
+    :type secret: str
+
+    :return: The JSON serialization of the dict representing the encrypted
+             content.
+    :rtype: str
+    """
+    enc_scheme = crypto.EncryptionSchemes.SYMKEY
+    enc_method = crypto.EncryptionMethods.AES_256_CTR
+    mac_method = crypto.MacMethods.HMAC
+    enc_iv, ciphertext = encrypt_sym(
+        str(docstr),  # encryption/decryption routines expect str
+        key)
+    mac = binascii.b2a_hex(  # store the mac as hex.
+        mac_doc(
+            doc_id,
+            doc_rev,
+            ciphertext,
+            enc_scheme,
+            enc_method,
+            enc_iv,
+            mac_method,
+            secret))
+    # Return a representation for the encrypted content. In the following, we
+    # convert binary data to hexadecimal representation so the JSON
+    # serialization does not complain about what it tries to serialize.
+    hex_ciphertext = binascii.b2a_hex(ciphertext)
+    logger.debug("encrypting doc: %s" % doc_id)
+    return json.dumps({
+        crypto.ENC_JSON_KEY: hex_ciphertext,
+        crypto.ENC_SCHEME_KEY: enc_scheme,
+        crypto.ENC_METHOD_KEY: enc_method,
+        crypto.ENC_IV_KEY: enc_iv,
+        crypto.MAC_KEY: mac,
+        crypto.MAC_METHOD_KEY: mac_method,
+    })
+
+
+def _verify_doc_mac(doc_id, doc_rev, ciphertext, enc_scheme, enc_method,
+                    enc_iv, mac_method, secret, doc_mac):
+    """
+    Verify that C{doc_mac} is a correct MAC for the given document.
+
+    :param doc_id: The id of the document.
+    :type doc_id: str
+    :param doc_rev: The revision of the document.
+    :type doc_rev: str
+    :param ciphertext: The content of the document.
+    :type ciphertext: str
+    :param enc_scheme: The encryption scheme.
+    :type enc_scheme: str
+    :param enc_method: The encryption method.
+    :type enc_method: str
+    :param enc_iv: The encryption initialization vector.
+    :type enc_iv: str
+    :param mac_method: The MAC method to use.
+    :type mac_method: str
+    :param secret: The Soledad storage secret
+    :type secret: str
+    :param doc_mac: The MAC to be verified against.
+    :type doc_mac: str
+
+    :raise crypto.UnknownMacMethodError: Raised when C{mac_method} is unknown.
+    :raise crypto.WrongMacError: Raised when MAC could not be verified.
+    """
+    calculated_mac = mac_doc(
+        doc_id,
+        doc_rev,
+        ciphertext,
+        enc_scheme,
+        enc_method,
+        enc_iv,
+        mac_method,
+        secret)
+    # we compare mac's hashes to avoid possible timing attacks that might
+    # exploit python's builtin comparison operator behaviour, which fails
+    # immediatelly when non-matching bytes are found.
+    doc_mac_hash = hashlib.sha256(
+        binascii.a2b_hex(  # the mac is stored as hex
+            doc_mac)).digest()
+    calculated_mac_hash = hashlib.sha256(calculated_mac).digest()
+
+    if doc_mac_hash != calculated_mac_hash:
+        logger.warn("wrong MAC while decrypting doc...")
+        raise crypto.WrongMacError("Could not authenticate document's "
+                                   "contents.")
+
+
+def decrypt_doc_dict(doc_dict, doc_id, doc_rev, key, secret):
+    """
+    Decrypt a symmetrically encrypted C{doc}'s content.
+
+    Return the JSON string representation of the document's decrypted content.
+
+    The passed doc_dict argument should have the following structure:
+
+        {
+            crypto.ENC_JSON_KEY: '<enc_blob>',
+            crypto.ENC_SCHEME_KEY: '<enc_scheme>',
+            crypto.ENC_METHOD_KEY: '<enc_method>',
+            crypto.ENC_IV_KEY: '<initial value used to encrypt>',  # (optional)
+            MAC_KEY: '<mac>'
+            crypto.MAC_METHOD_KEY: 'hmac'
+        }
+
+    C{enc_blob} is the encryption of the JSON serialization of the document's
+    content. For now Soledad just deals with documents whose C{enc_scheme} is
+    crypto.EncryptionSchemes.SYMKEY and C{enc_method} is
+    crypto.EncryptionMethods.AES_256_CTR.
+
+    :param doc_dict: The content of the document to be decrypted.
+    :type doc_dict: dict
+
+    :param doc_id: The document id.
+    :type doc_id: str
+
+    :param doc_rev: The document revision.
+    :type doc_rev: str
+
+    :param key: The key used to encrypt ``data`` (must be 256 bits long).
+    :type key: str
+
+    :param secret: The Soledad storage secret.
+    :type secret: str
+
+    :return: The JSON serialization of the decrypted content.
+    :rtype: str
+
+    :raise UnknownEncryptionMethodError: Raised when trying to decrypt from an
+        unknown encryption method.
+    """
+    # assert document dictionary structure
+    expected_keys = set([
+        crypto.ENC_JSON_KEY,
+        crypto.ENC_SCHEME_KEY,
+        crypto.ENC_METHOD_KEY,
+        crypto.ENC_IV_KEY,
+        crypto.MAC_KEY,
+        crypto.MAC_METHOD_KEY,
+    ])
+    soledad_assert(expected_keys.issubset(set(doc_dict.keys())))
+
+    ciphertext = binascii.a2b_hex(doc_dict[crypto.ENC_JSON_KEY])
+    enc_scheme = doc_dict[crypto.ENC_SCHEME_KEY]
+    enc_method = doc_dict[crypto.ENC_METHOD_KEY]
+    enc_iv = doc_dict[crypto.ENC_IV_KEY]
+    doc_mac = doc_dict[crypto.MAC_KEY]
+    mac_method = doc_dict[crypto.MAC_METHOD_KEY]
+
+    soledad_assert(enc_scheme == crypto.EncryptionSchemes.SYMKEY)
+
+    _verify_doc_mac(
+        doc_id, doc_rev, ciphertext, enc_scheme, enc_method,
+        enc_iv, mac_method, secret, doc_mac)
+
+    return decrypt_sym(ciphertext, key, enc_iv)
+
+
+def is_symmetrically_encrypted(doc):
+    """
+    Return True if the document was symmetrically encrypted.
+
+    :param doc: The document to check.
+    :type doc: Document
+
+    :rtype: bool
+    """
+    if doc.content and crypto.ENC_SCHEME_KEY in doc.content:
+        if doc.content[crypto.ENC_SCHEME_KEY] \
+                == crypto.EncryptionSchemes.SYMKEY:
+            return True
+    return False
diff --git a/src/leap/soledad/client/events.py b/src/leap/soledad/client/events.py
new file mode 100644
index 00000000..058be59c
--- /dev/null
+++ b/src/leap/soledad/client/events.py
@@ -0,0 +1,54 @@
+# -*- coding: utf-8 -*-
+# signal.py
+# Copyright (C) 2014 LEAP
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+
+"""
+Signaling functions.
+"""
+
+from leap.common.events import emit_async
+from leap.common.events import catalog
+
+
+SOLEDAD_CREATING_KEYS = catalog.SOLEDAD_CREATING_KEYS
+SOLEDAD_DONE_CREATING_KEYS = catalog.SOLEDAD_DONE_CREATING_KEYS
+SOLEDAD_DOWNLOADING_KEYS = catalog.SOLEDAD_DOWNLOADING_KEYS
+SOLEDAD_DONE_DOWNLOADING_KEYS = \
+    catalog.SOLEDAD_DONE_DOWNLOADING_KEYS
+SOLEDAD_UPLOADING_KEYS = catalog.SOLEDAD_UPLOADING_KEYS
+SOLEDAD_DONE_UPLOADING_KEYS = \
+    catalog.SOLEDAD_DONE_UPLOADING_KEYS
+SOLEDAD_NEW_DATA_TO_SYNC = catalog.SOLEDAD_NEW_DATA_TO_SYNC
+SOLEDAD_DONE_DATA_SYNC = catalog.SOLEDAD_DONE_DATA_SYNC
+SOLEDAD_SYNC_SEND_STATUS = catalog.SOLEDAD_SYNC_SEND_STATUS
+SOLEDAD_SYNC_RECEIVE_STATUS = catalog.SOLEDAD_SYNC_RECEIVE_STATUS
+
+
+__all__ = [
+    "catalog",
+    "emit_async",
+    "SOLEDAD_CREATING_KEYS",
+    "SOLEDAD_DONE_CREATING_KEYS",
+    "SOLEDAD_DOWNLOADING_KEYS",
+    "SOLEDAD_DONE_DOWNLOADING_KEYS",
+    "SOLEDAD_UPLOADING_KEYS",
+    "SOLEDAD_DONE_UPLOADING_KEYS",
+    "SOLEDAD_NEW_DATA_TO_SYNC",
+    "SOLEDAD_DONE_DATA_SYNC",
+    "SOLEDAD_SYNC_SEND_STATUS",
+    "SOLEDAD_SYNC_RECEIVE_STATUS",
+]
diff --git a/src/leap/soledad/client/examples/README b/src/leap/soledad/client/examples/README
new file mode 100644
index 00000000..3aed8377
--- /dev/null
+++ b/src/leap/soledad/client/examples/README
@@ -0,0 +1,4 @@
+Right now, you can find here both an example of use
+and the benchmarking scripts.
+TODO move benchmark scripts to root scripts/ folder,
+and leave here only a minimal example.
diff --git a/src/leap/soledad/client/examples/benchmarks/.gitignore b/src/leap/soledad/client/examples/benchmarks/.gitignore
new file mode 100644
index 00000000..2211df63
--- /dev/null
+++ b/src/leap/soledad/client/examples/benchmarks/.gitignore
@@ -0,0 +1 @@
+*.txt
diff --git a/src/leap/soledad/client/examples/benchmarks/get_sample.sh b/src/leap/soledad/client/examples/benchmarks/get_sample.sh
new file mode 100755
index 00000000..1995eee1
--- /dev/null
+++ b/src/leap/soledad/client/examples/benchmarks/get_sample.sh
@@ -0,0 +1,3 @@
+#!/bin/sh
+mkdir tmp
+wget http://www.gutenberg.org/cache/epub/101/pg101.txt -O hacker_crackdown.txt
diff --git a/src/leap/soledad/client/examples/benchmarks/measure_index_times.py b/src/leap/soledad/client/examples/benchmarks/measure_index_times.py
new file mode 100644
index 00000000..f9349758
--- /dev/null
+++ b/src/leap/soledad/client/examples/benchmarks/measure_index_times.py
@@ -0,0 +1,179 @@
+# -*- coding: utf-8 -*-
+# measure_index_times.py
+# Copyright (C) 2014 LEAP
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+"""
+Measure u1db retrieval times for different u1db index situations.
+"""
+from __future__ import print_function
+from functools import partial
+import datetime
+import hashlib
+import os
+import sys
+
+from twisted.internet import defer, reactor
+
+from leap.soledad.common import l2db
+from leap.soledad.client import adbapi
+from leap.soledad.client._db.sqlcipher import SQLCipherOptions
+
+
+folder = os.environ.get("TMPDIR", "tmp")
+numdocs = int(os.environ.get("DOCS", "1000"))
+silent = os.environ.get("SILENT", False)
+tmpdb = os.path.join(folder, "test.soledad")
+
+
+sample_file = os.environ.get("SAMPLE", "hacker_crackdown.txt")
+sample_path = os.path.join(os.curdir, sample_file)
+
+try:
+    with open(sample_file) as f:
+        SAMPLE = f.readlines()
+except Exception:
+    print("[!] Problem opening sample file. Did you download "
+          "the sample, or correctly set 'SAMPLE' env var?")
+    sys.exit(1)
+
+if numdocs > len(SAMPLE):
+    print("[!] Sorry! The requested DOCS number is larger than "
+          "the num of lines in our sample file")
+    sys.exit(1)
+
+
+def debug(*args):
+    if not silent:
+        print(*args)
+
+
+debug("[+] db path:", tmpdb)
+debug("[+] num docs", numdocs)
+
+if os.path.isfile(tmpdb):
+    debug("[+] Removing existing db file...")
+    os.remove(tmpdb)
+
+start_time = datetime.datetime.now()
+
+opts = SQLCipherOptions(tmpdb, "secret", create=True)
+dbpool = adbapi.getConnectionPool(opts)
+
+
+def createDoc(doc):
+    return dbpool.runU1DBQuery("create_doc", doc)
+
+
+db_indexes = {
+    'by-chash': ['chash'],
+    'by-number': ['number']}
+
+
+def create_indexes(_):
+    deferreds = []
+    for index, definition in db_indexes.items():
+        d = dbpool.runU1DBQuery("create_index", index, *definition)
+        deferreds.append(d)
+    return defer.gatherResults(deferreds)
+
+
+class TimeWitness(object):
+    def __init__(self, init_time):
+        self.init_time = init_time
+
+    def get_time_count(self):
+        return datetime.datetime.now() - self.init_time
+
+
+def get_from_index(_):
+    init_time = datetime.datetime.now()
+    debug("GETTING FROM INDEX...", init_time)
+
+    def printValue(res, time):
+        print("RESULT->", res)
+        print("Index Query Took: ", time.get_time_count())
+        return res
+
+    d = dbpool.runU1DBQuery(
+        "get_from_index", "by-chash",
+        # "1150c7f10fabce0a57ce13071349fc5064f15bdb0cc1bf2852f74ef3f103aff5")
+        # XXX this is line 89 from the hacker crackdown...
+        # Should accept any other optional hash as an enviroment variable.
+        "57793320d4997a673fc7062652da0596c36a4e9fbe31310d2281e67d56d82469")
+    d.addCallback(printValue, TimeWitness(init_time))
+    return d
+
+
+def getAllDocs():
+    return dbpool.runU1DBQuery("get_all_docs")
+
+
+def errBack(e):
+    debug("[!] ERROR FOUND!!!")
+    e.printTraceback()
+    reactor.stop()
+
+
+def countDocs(_):
+    debug("counting docs...")
+    d = getAllDocs()
+    d.addCallbacks(printResult, errBack)
+    d.addCallbacks(allDone, errBack)
+    return d
+
+
+def printResult(r, **kwargs):
+    if kwargs:
+        debug(*kwargs.values())
+    elif isinstance(r, l2db.Document):
+        debug(r.doc_id, r.content['number'])
+    else:
+        len_results = len(r[1])
+        debug("GOT %s results" % len(r[1]))
+
+        if len_results == numdocs:
+            debug("ALL GOOD")
+        else:
+            debug("[!] MISSING DOCS!!!!!")
+            raise ValueError("We didn't expect this result len")
+
+
+def allDone(_):
+    debug("ALL DONE!")
+
+    end_time = datetime.datetime.now()
+    print((end_time - start_time).total_seconds())
+    reactor.stop()
+
+
+def insert_docs(_):
+    deferreds = []
+    for i in range(numdocs):
+        payload = SAMPLE[i]
+        chash = hashlib.sha256(payload).hexdigest()
+        doc = {"number": i, "payload": payload, 'chash': chash}
+        d = createDoc(doc)
+        d.addCallbacks(partial(printResult, i=i, chash=chash, payload=payload),
+                       lambda e: e.printTraceback())
+        deferreds.append(d)
+    return defer.gatherResults(deferreds, consumeErrors=True)
+
+
+d = create_indexes(None)
+d.addCallback(insert_docs)
+d.addCallback(get_from_index)
+d.addCallback(countDocs)
+
+reactor.run()
diff --git a/src/leap/soledad/client/examples/benchmarks/measure_index_times_custom_docid.py b/src/leap/soledad/client/examples/benchmarks/measure_index_times_custom_docid.py
new file mode 100644
index 00000000..4f273c64
--- /dev/null
+++ b/src/leap/soledad/client/examples/benchmarks/measure_index_times_custom_docid.py
@@ -0,0 +1,179 @@
+# -*- coding: utf-8 -*-
+# measure_index_times.py
+# Copyright (C) 2014 LEAP
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+"""
+Measure u1db retrieval times for different u1db index situations.
+"""
+from __future__ import print_function
+from functools import partial
+import datetime
+import hashlib
+import os
+import sys
+
+from twisted.internet import defer, reactor
+
+from leap.soledad.client import adbapi
+from leap.soledad.client._db.sqlcipher import SQLCipherOptions
+from leap.soledad.common import l2db
+
+
+folder = os.environ.get("TMPDIR", "tmp")
+numdocs = int(os.environ.get("DOCS", "1000"))
+silent = os.environ.get("SILENT", False)
+tmpdb = os.path.join(folder, "test.soledad")
+
+
+sample_file = os.environ.get("SAMPLE", "hacker_crackdown.txt")
+sample_path = os.path.join(os.curdir, sample_file)
+
+try:
+    with open(sample_file) as f:
+        SAMPLE = f.readlines()
+except Exception:
+    print("[!] Problem opening sample file. Did you download "
+          "the sample, or correctly set 'SAMPLE' env var?")
+    sys.exit(1)
+
+if numdocs > len(SAMPLE):
+    print("[!] Sorry! The requested DOCS number is larger than "
+          "the num of lines in our sample file")
+    sys.exit(1)
+
+
+def debug(*args):
+    if not silent:
+        print(*args)
+
+
+debug("[+] db path:", tmpdb)
+debug("[+] num docs", numdocs)
+
+if os.path.isfile(tmpdb):
+    debug("[+] Removing existing db file...")
+    os.remove(tmpdb)
+
+start_time = datetime.datetime.now()
+
+opts = SQLCipherOptions(tmpdb, "secret", create=True)
+dbpool = adbapi.getConnectionPool(opts)
+
+
+def createDoc(doc, doc_id):
+    return dbpool.runU1DBQuery("create_doc", doc, doc_id=doc_id)
+
+
+db_indexes = {
+    'by-chash': ['chash'],
+    'by-number': ['number']}
+
+
+def create_indexes(_):
+    deferreds = []
+    for index, definition in db_indexes.items():
+        d = dbpool.runU1DBQuery("create_index", index, *definition)
+        deferreds.append(d)
+    return defer.gatherResults(deferreds)
+
+
+class TimeWitness(object):
+    def __init__(self, init_time):
+        self.init_time = init_time
+
+    def get_time_count(self):
+        return datetime.datetime.now() - self.init_time
+
+
+def get_from_index(_):
+    init_time = datetime.datetime.now()
+    debug("GETTING FROM INDEX...", init_time)
+
+    def printValue(res, time):
+        print("RESULT->", res)
+        print("Index Query Took: ", time.get_time_count())
+        return res
+
+    d = dbpool.runU1DBQuery(
+        "get_doc",
+        # "1150c7f10fabce0a57ce13071349fc5064f15bdb0cc1bf2852f74ef3f103aff5")
+        # XXX this is line 89 from the hacker crackdown...
+        # Should accept any other optional hash as an enviroment variable.
+        "57793320d4997a673fc7062652da0596c36a4e9fbe31310d2281e67d56d82469")
+    d.addCallback(printValue, TimeWitness(init_time))
+    return d
+
+
+def getAllDocs():
+    return dbpool.runU1DBQuery("get_all_docs")
+
+
+def errBack(e):
+    debug("[!] ERROR FOUND!!!")
+    e.printTraceback()
+    reactor.stop()
+
+
+def countDocs(_):
+    debug("counting docs...")
+    d = getAllDocs()
+    d.addCallbacks(printResult, errBack)
+    d.addCallbacks(allDone, errBack)
+    return d
+
+
+def printResult(r, **kwargs):
+    if kwargs:
+        debug(*kwargs.values())
+    elif isinstance(r, l2db.Document):
+        debug(r.doc_id, r.content['number'])
+    else:
+        len_results = len(r[1])
+        debug("GOT %s results" % len(r[1]))
+
+        if len_results == numdocs:
+            debug("ALL GOOD")
+        else:
+            debug("[!] MISSING DOCS!!!!!")
+            raise ValueError("We didn't expect this result len")
+
+
+def allDone(_):
+    debug("ALL DONE!")
+
+    end_time = datetime.datetime.now()
+    print((end_time - start_time).total_seconds())
+    reactor.stop()
+
+
+def insert_docs(_):
+    deferreds = []
+    for i in range(numdocs):
+        payload = SAMPLE[i]
+        chash = hashlib.sha256(payload).hexdigest()
+        doc = {"number": i, "payload": payload, 'chash': chash}
+        d = createDoc(doc, doc_id=chash)
+        d.addCallbacks(partial(printResult, i=i, chash=chash, payload=payload),
+                       lambda e: e.printTraceback())
+        deferreds.append(d)
+    return defer.gatherResults(deferreds, consumeErrors=True)
+
+
+d = create_indexes(None)
+d.addCallback(insert_docs)
+d.addCallback(get_from_index)
+d.addCallback(countDocs)
+
+reactor.run()
diff --git a/src/leap/soledad/client/examples/compare.txt b/src/leap/soledad/client/examples/compare.txt
new file mode 100644
index 00000000..19a1325a
--- /dev/null
+++ b/src/leap/soledad/client/examples/compare.txt
@@ -0,0 +1,8 @@
+TIMES=100 TMPDIR=/media/sdb5/leap python use_adbapi.py  1.34s user 0.16s system 53% cpu 2.832 total
+TIMES=100 TMPDIR=/media/sdb5/leap python use_api.py  1.22s user 0.14s system 62% cpu 2.181 total
+
+TIMES=1000 TMPDIR=/media/sdb5/leap python use_api.py  2.18s user 0.34s system 27% cpu 9.213 total
+TIMES=1000 TMPDIR=/media/sdb5/leap python use_adbapi.py  2.40s user 0.34s system 39% cpu 7.004 total
+
+TIMES=5000 TMPDIR=/media/sdb5/leap python use_api.py  6.63s user 1.27s system 13% cpu 57.882 total
+TIMES=5000 TMPDIR=/media/sdb5/leap python use_adbapi.py  6.84s user 1.26s system 36% cpu 22.367 total
diff --git a/src/leap/soledad/client/examples/manifest.phk b/src/leap/soledad/client/examples/manifest.phk
new file mode 100644
index 00000000..2c86c07d
--- /dev/null
+++ b/src/leap/soledad/client/examples/manifest.phk
@@ -0,0 +1,50 @@
+The Hacker's Manifesto
+
+The Hacker's Manifesto
+by: The Mentor
+
+Another one got caught today, it's all over the papers. "Teenager 
+Arrested in Computer Crime Scandal", "Hacker Arrested after Bank 
+Tampering." "Damn kids. They're all alike." But did you, in your 
+three-piece psychology and 1950's technobrain, ever take a look behind 
+the eyes of the hacker? Did you ever wonder what made him tick, what 
+forces shaped him, what may have molded him? I am a hacker, enter my 
+world. Mine is a world that begins with school. I'm smarter than most of 
+the other kids, this crap they teach us bores me. "Damn underachiever. 
+They're all alike." I'm in junior high or high school.  I've listened to 
+teachers explain for the fifteenth time how to reduce a fraction. I 
+understand it. "No, Ms. Smith, I didn't show my work. I did it in
+my head." "Damn kid. Probably copied it. They're all alike." I made a 
+discovery today. I found a computer. Wait a second, this is cool. It does 
+what I want it to. If it makes a mistake, it's because I screwed it up. 
+Not because it doesn't like me, or feels threatened by me, or thinks I'm 
+a smart ass, or doesn't like teaching and shouldn't be here. Damn kid. 
+All he does is play games. They're all alike. And then it happened... a 
+door opened to a world... rushing through the phone line like heroin 
+through an addict's veins, an electronic pulse is sent out, a refuge from 
+the day-to-day incompetencies is sought... a board is found. "This is 
+it... this is where I belong..." I know everyone here... even if I've 
+never met them, never talked to them, may never hear from them again... I 
+know you all... Damn kid. Tying up the phone line again. They're all 
+alike... You bet your ass we're all alike... we've been spoon-fed baby 
+food at school when we hungered for steak... the bits of meat that you 
+did let slip through were pre-chewed and tasteless. We've been dominated 
+by sadists, or ignored by the apathetic. The few that had something to 
+teach found us willing pupils, but those few are like drops of water in 
+the desert. This is our world now... the world of the electron and the 
+switch, the beauty of the baud. We make use of a service already existing 
+without paying for what could be dirt-cheap if it wasn't run by 
+profiteering gluttons, and you call us criminals. We explore... and you 
+call us criminals. We seek after knowledge... and you call us criminals. 
+We exist without skin color, without nationality, without religious 
+bias... and you call us criminals. You build atomic bombs, you wage wars, 
+you murder, cheat, and lie to us and try to make us believe it's for our 
+own good, yet we're the criminals. Yes, I am a criminal. My crime is that 
+of curiosity. My crime is that of judging people by what they say and 
+think, not what they look like. My crime is that of outsmarting you, 
+something that you will never forgive me for. I am a hacker, and this is 
+my manifesto.  You may stop this individual, but you can't stop us all... 
+after all, we're all alike.
+
+This was the last published file written by The Mentor. Shortly after 
+releasing it, he was busted by the FBI. The Mentor, sadly missed.
diff --git a/src/leap/soledad/client/examples/plot-async-db.py b/src/leap/soledad/client/examples/plot-async-db.py
new file mode 100644
index 00000000..018a1a1d
--- /dev/null
+++ b/src/leap/soledad/client/examples/plot-async-db.py
@@ -0,0 +1,45 @@
+import csv
+from matplotlib import pyplot as plt
+
+FILE = "bench.csv"
+
+# config the plot
+plt.xlabel('number of inserts')
+plt.ylabel('time (seconds)')
+plt.title('SQLCipher parallelization')
+
+kwargs = {
+    'linewidth': 1.0,
+    'linestyle': '-',
+}
+
+series = (('sync', 'r'),
+          ('async', 'g'))
+
+data = {'mark': [],
+        'sync': [],
+        'async': []}
+
+with open(FILE, 'rb') as csvfile:
+    series_reader = csv.reader(csvfile, delimiter=',')
+    for m, s, a in series_reader:
+        data['mark'].append(int(m))
+        data['sync'].append(float(s))
+        data['async'].append(float(a))
+
+xmax = max(data['mark'])
+xmin = min(data['mark'])
+ymax = max(data['sync'] + data['async'])
+ymin = min(data['sync'] + data['async'])
+
+for run in series:
+    name = run[0]
+    color = run[1]
+    plt.plot(data['mark'], data[name], label=name, color=color, **kwargs)
+
+plt.axes().annotate("", xy=(xmax, ymax))
+plt.axes().annotate("", xy=(xmin, ymin))
+
+plt.grid()
+plt.legend()
+plt.show()
diff --git a/src/leap/soledad/client/examples/run_benchmark.py b/src/leap/soledad/client/examples/run_benchmark.py
new file mode 100644
index 00000000..ddedf433
--- /dev/null
+++ b/src/leap/soledad/client/examples/run_benchmark.py
@@ -0,0 +1,30 @@
+"""
+Run a mini-benchmark between regular api and dbapi
+"""
+import commands
+import os
+import time
+
+TMPDIR = os.environ.get("TMPDIR", "/tmp")
+CSVFILE = 'bench.csv'
+
+cmd = "SILENT=1 TIMES={times} TMPDIR={tmpdir} python ./use_{version}api.py"
+
+
+def parse_time(r):
+    return r.split('\n')[-1]
+
+
+with open(CSVFILE, 'w') as log:
+
+    for times in range(0, 10000, 500):
+        cmd1 = cmd.format(times=times, tmpdir=TMPDIR, version="")
+        sync_time = parse_time(commands.getoutput(cmd1))
+
+        cmd2 = cmd.format(times=times, tmpdir=TMPDIR, version="adb")
+        async_time = parse_time(commands.getoutput(cmd2))
+
+        print times, sync_time, async_time
+        log.write("%s, %s, %s\n" % (times, sync_time, async_time))
+        log.flush()
+        time.sleep(2)
diff --git a/src/leap/soledad/client/examples/soledad_sync.py b/src/leap/soledad/client/examples/soledad_sync.py
new file mode 100644
index 00000000..3aed10eb
--- /dev/null
+++ b/src/leap/soledad/client/examples/soledad_sync.py
@@ -0,0 +1,63 @@
+from leap.bitmask.config.providerconfig import ProviderConfig
+from leap.bitmask.crypto.srpauth import SRPAuth
+from leap.soledad.client import Soledad
+from twisted.internet import reactor
+import logging
+logging.basicConfig(level=logging.DEBUG)
+
+
+# EDIT THIS --------------------------------------------
+user = u"USERNAME"
+uuid = u"USERUUID"
+_pass = u"USERPASS"
+server_url = "https://soledad.server.example.org:2323"
+# EDIT THIS --------------------------------------------
+
+secrets_path = "/tmp/%s.secrets" % uuid
+local_db_path = "/tmp/%s.soledad" % uuid
+cert_file = "/tmp/cacert.pem"
+provider_config = '/tmp/cdev.json'
+
+
+provider = ProviderConfig()
+provider.load(provider_config)
+
+soledad = None
+
+
+def printStuff(r):
+    print r
+
+
+def printErr(err):
+    logging.exception(err.value)
+
+
+def init_soledad(_):
+    token = srpauth.get_token()
+    print "token", token
+
+    global soledad
+    soledad = Soledad(uuid, _pass, secrets_path, local_db_path,
+                      server_url, cert_file,
+                      auth_token=token)
+
+    def getall(_):
+        d = soledad.get_all_docs()
+        return d
+
+    d1 = soledad.create_doc({"test": 42})
+    d1.addCallback(getall)
+    d1.addCallbacks(printStuff, printErr)
+
+    d2 = soledad.sync()
+    d2.addCallbacks(printStuff, printErr)
+    d2.addBoth(lambda r: reactor.stop())
+
+
+srpauth = SRPAuth(provider)
+
+d = srpauth.authenticate(user, _pass)
+d.addCallbacks(init_soledad, printErr)
+
+reactor.run()
diff --git a/src/leap/soledad/client/examples/use_adbapi.py b/src/leap/soledad/client/examples/use_adbapi.py
new file mode 100644
index 00000000..ddb1eaae
--- /dev/null
+++ b/src/leap/soledad/client/examples/use_adbapi.py
@@ -0,0 +1,105 @@
+# -*- coding: utf-8 -*-
+# use_adbapi.py
+# Copyright (C) 2014 LEAP
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+"""
+Example of use of the asynchronous soledad api.
+"""
+from __future__ import print_function
+import datetime
+import os
+
+from twisted.internet import defer, reactor
+
+from leap.soledad.client import adbapi
+from leap.soledad.client._db.sqlcipher import SQLCipherOptions
+from leap.soledad.common import l2db
+
+
+folder = os.environ.get("TMPDIR", "tmp")
+times = int(os.environ.get("TIMES", "1000"))
+silent = os.environ.get("SILENT", False)
+
+tmpdb = os.path.join(folder, "test.soledad")
+
+
+def debug(*args):
+    if not silent:
+        print(*args)
+
+
+debug("[+] db path:", tmpdb)
+debug("[+] times", times)
+
+if os.path.isfile(tmpdb):
+    debug("[+] Removing existing db file...")
+    os.remove(tmpdb)
+
+start_time = datetime.datetime.now()
+
+opts = SQLCipherOptions(tmpdb, "secret", create=True)
+dbpool = adbapi.getConnectionPool(opts)
+
+
+def createDoc(doc):
+    return dbpool.runU1DBQuery("create_doc", doc)
+
+
+def getAllDocs():
+    return dbpool.runU1DBQuery("get_all_docs")
+
+
+def countDocs(_):
+    debug("counting docs...")
+    d = getAllDocs()
+    d.addCallbacks(printResult, lambda e: e.printTraceback())
+    d.addBoth(allDone)
+
+
+def printResult(r):
+    if isinstance(r, l2db.Document):
+        debug(r.doc_id, r.content['number'])
+    else:
+        len_results = len(r[1])
+        debug("GOT %s results" % len(r[1]))
+
+        if len_results == times:
+            debug("ALL GOOD")
+        else:
+            raise ValueError("We didn't expect this result len")
+
+
+def allDone(_):
+    debug("ALL DONE!")
+    if silent:
+        end_time = datetime.datetime.now()
+        print((end_time - start_time).total_seconds())
+    reactor.stop()
+
+
+deferreds = []
+payload = open('manifest.phk').read()
+
+for i in range(times):
+    doc = {"number": i, "payload": payload}
+    d = createDoc(doc)
+    d.addCallbacks(printResult, lambda e: e.printTraceback())
+    deferreds.append(d)
+
+
+all_done = defer.gatherResults(deferreds, consumeErrors=True)
+all_done.addCallback(countDocs)
+
+reactor.run()
diff --git a/src/leap/soledad/client/examples/use_api.py b/src/leap/soledad/client/examples/use_api.py
new file mode 100644
index 00000000..db77c4b3
--- /dev/null
+++ b/src/leap/soledad/client/examples/use_api.py
@@ -0,0 +1,69 @@
+# -*- coding: utf-8 -*-
+# use_api.py
+# Copyright (C) 2014 LEAP
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+"""
+Example of use of the soledad api.
+"""
+from __future__ import print_function
+import datetime
+import os
+
+from leap.soledad.client import sqlcipher
+from leap.soledad.client.sqlcipher import SQLCipherOptions
+
+
+folder = os.environ.get("TMPDIR", "tmp")
+times = int(os.environ.get("TIMES", "1000"))
+silent = os.environ.get("SILENT", False)
+
+tmpdb = os.path.join(folder, "test.soledad")
+
+
+def debug(*args):
+    if not silent:
+        print(*args)
+
+
+debug("[+] db path:", tmpdb)
+debug("[+] times", times)
+
+if os.path.isfile(tmpdb):
+    debug("[+] Removing existing db file...")
+    os.remove(tmpdb)
+
+start_time = datetime.datetime.now()
+
+opts = SQLCipherOptions(tmpdb, "secret", create=True)
+db = sqlcipher.SQLCipherDatabase(opts)
+
+
+def allDone():
+    debug("ALL DONE!")
+
+
+payload = open('manifest.phk').read()
+
+for i in range(times):
+    doc = {"number": i, "payload": payload}
+    d = db.create_doc(doc)
+    debug(d.doc_id, d.content['number'])
+
+debug("Count", len(db.get_all_docs()[1]))
+if silent:
+    end_time = datetime.datetime.now()
+    print((end_time - start_time).total_seconds())
+
+allDone()
diff --git a/src/leap/soledad/client/http_target/__init__.py b/src/leap/soledad/client/http_target/__init__.py
new file mode 100644
index 00000000..b67d03f6
--- /dev/null
+++ b/src/leap/soledad/client/http_target/__init__.py
@@ -0,0 +1,94 @@
+# -*- coding: utf-8 -*-
+# __init__.py
+# Copyright (C) 2015 LEAP
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+
+"""
+A U1DB backend for encrypting data before sending to server and decrypting
+after receiving.
+"""
+
+
+import os
+
+from twisted.web.client import Agent
+from twisted.internet import reactor
+
+from leap.common.certs import get_compatible_ssl_context_factory
+from leap.soledad.common.log import getLogger
+from leap.soledad.client.http_target.send import HTTPDocSender
+from leap.soledad.client.http_target.api import SyncTargetAPI
+from leap.soledad.client.http_target.fetch import HTTPDocFetcher
+from leap.soledad.client import crypto as old_crypto
+
+
+logger = getLogger(__name__)
+
+
+# we may want to collect statistics from the sync process
+DO_STATS = False
+if os.environ.get('SOLEDAD_STATS'):
+    DO_STATS = True
+
+
+class SoledadHTTPSyncTarget(SyncTargetAPI, HTTPDocSender, HTTPDocFetcher):
+
+    """
+    A SyncTarget that encrypts data before sending and decrypts data after
+    receiving.
+
+    Normally encryption will have been written to the sync database upon
+    document modification. The sync database is also used to write temporarily
+    the parsed documents that the remote send us, before being decrypted and
+    written to the main database.
+    """
+    def __init__(self, url, source_replica_uid, creds, crypto, cert_file):
+        """
+        Initialize the sync target.
+
+        :param url: The server sync url.
+        :type url: str
+        :param source_replica_uid: The source replica uid which we use when
+                                   deferring decryption.
+        :type source_replica_uid: str
+        :param creds: A dictionary containing the uuid and token.
+        :type creds: creds
+        :param crypto: An instance of SoledadCrypto so we can encrypt/decrypt
+                        document contents when syncing.
+        :type crypto: soledad._crypto.SoledadCrypto
+        :param cert_file: Path to the certificate of the ca used to validate
+                          the SSL certificate used by the remote soledad
+                          server.
+        :type cert_file: str
+        """
+        if url.endswith("/"):
+            url = url[:-1]
+        self._url = str(url) + "/sync-from/" + str(source_replica_uid)
+        self.source_replica_uid = source_replica_uid
+        self._auth_header = None
+        self._uuid = None
+        self.set_creds(creds)
+        self._crypto = crypto
+        # TODO: DEPRECATED CRYPTO
+        self._deprecated_crypto = old_crypto.SoledadCrypto(crypto.secret)
+        self._insert_doc_cb = None
+
+        # Twisted default Agent with our own ssl context factory
+        factory = get_compatible_ssl_context_factory(cert_file)
+        self._http = Agent(reactor, factory)
+
+        if DO_STATS:
+            self.sync_exchange_phase = [0]
diff --git a/src/leap/soledad/client/http_target/api.py b/src/leap/soledad/client/http_target/api.py
new file mode 100644
index 00000000..c68185c6
--- /dev/null
+++ b/src/leap/soledad/client/http_target/api.py
@@ -0,0 +1,248 @@
+# -*- coding: utf-8 -*-
+# api.py
+# Copyright (C) 2015 LEAP
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+import os
+import json
+import base64
+
+from six import StringIO
+from uuid import uuid4
+
+from twisted.internet import defer
+from twisted.web.http_headers import Headers
+from twisted.web.client import FileBodyProducer
+
+from leap.soledad.client.http_target.support import readBody
+from leap.soledad.common.errors import InvalidAuthTokenError
+from leap.soledad.common.l2db.errors import HTTPError
+from leap.soledad.common.l2db import SyncTarget
+
+
+# we may want to collect statistics from the sync process
+DO_STATS = False
+if os.environ.get('SOLEDAD_STATS'):
+    DO_STATS = True
+
+
+class SyncTargetAPI(SyncTarget):
+    """
+    Declares public methods and implements u1db.SyncTarget.
+    """
+
+    @property
+    def uuid(self):
+        return self._uuid
+
+    def set_creds(self, creds):
+        """
+        Update credentials.
+
+        :param creds: A dictionary containing the uuid and token.
+        :type creds: dict
+        """
+        uuid = creds['token']['uuid']
+        token = creds['token']['token']
+        self._uuid = uuid
+        auth = '%s:%s' % (uuid, token)
+        b64_token = base64.b64encode(auth)
+        self._auth_header = {'Authorization': ['Token %s' % b64_token]}
+
+    @property
+    def _base_header(self):
+        return self._auth_header.copy() if self._auth_header else {}
+
+    def _http_request(self, url, method='GET', body=None, headers=None,
+                      content_type=None, body_reader=readBody,
+                      body_producer=None):
+        headers = headers or self._base_header
+        if content_type:
+            headers.update({'content-type': [content_type]})
+        if not body_producer and body:
+            body = FileBodyProducer(StringIO(body))
+        elif body_producer:
+            # Upload case, check send.py
+            body = body_producer(body)
+        d = self._http.request(
+            method, url, headers=Headers(headers), bodyProducer=body)
+        d.addCallback(body_reader)
+        d.addErrback(_unauth_to_invalid_token_error)
+        return d
+
+    @defer.inlineCallbacks
+    def get_sync_info(self, source_replica_uid):
+        """
+        Return information about known state of remote database.
+
+        Return the replica_uid and the current database generation of the
+        remote database, and its last-seen database generation for the client
+        replica.
+
+        :param source_replica_uid: The client-size replica uid.
+        :type source_replica_uid: str
+
+        :return: A deferred which fires with (target_replica_uid,
+                 target_replica_generation, target_trans_id,
+                 source_replica_last_known_generation,
+                 source_replica_last_known_transaction_id)
+        :rtype: twisted.internet.defer.Deferred
+        """
+        raw = yield self._http_request(self._url)
+        res = json.loads(raw)
+        defer.returnValue((
+            res['target_replica_uid'],
+            res['target_replica_generation'],
+            res['target_replica_transaction_id'],
+            res['source_replica_generation'],
+            res['source_transaction_id']
+        ))
+
+    def record_sync_info(
+            self, source_replica_uid, source_replica_generation,
+            source_replica_transaction_id):
+        """
+        Record tip information for another replica.
+
+        After sync_exchange has been processed, the caller will have
+        received new content from this replica. This call allows the
+        source replica instigating the sync to inform us what their
+        generation became after applying the documents we returned.
+
+        This is used to allow future sync operations to not need to repeat data
+        that we just talked about. It also means that if this is called at the
+        wrong time, there can be database records that will never be
+        synchronized.
+
+        :param source_replica_uid: The identifier for the source replica.
+        :type source_replica_uid: str
+        :param source_replica_generation: The database generation for the
+                                          source replica.
+        :type source_replica_generation: int
+        :param source_replica_transaction_id: The transaction id associated
+                                              with the source replica
+                                              generation.
+        :type source_replica_transaction_id: str
+
+        :return: A deferred which fires with the result of the query.
+        :rtype: twisted.internet.defer.Deferred
+        """
+        data = json.dumps({
+            'generation': source_replica_generation,
+            'transaction_id': source_replica_transaction_id
+        })
+        return self._http_request(
+            self._url,
+            method='PUT',
+            body=data,
+            content_type='application/json')
+
+    @defer.inlineCallbacks
+    def sync_exchange(self, docs_by_generation, source_replica_uid,
+                      last_known_generation, last_known_trans_id,
+                      insert_doc_cb, ensure_callback=None,
+                      sync_id=None):
+        """
+        Find out which documents the remote database does not know about,
+        encrypt and send them. After that, receive documents from the remote
+        database.
+
+        :param docs_by_generations: A list of (doc_id, generation, trans_id)
+                                    of local documents that were changed since
+                                    the last local generation the remote
+                                    replica knows about.
+        :type docs_by_generations: list of tuples
+
+        :param source_replica_uid: The uid of the source replica.
+        :type source_replica_uid: str
+
+        :param last_known_generation: Target's last known generation.
+        :type last_known_generation: int
+
+        :param last_known_trans_id: Target's last known transaction id.
+        :type last_known_trans_id: str
+
+        :param insert_doc_cb: A callback for inserting received documents from
+                              target. If not overriden, this will call u1db
+                              insert_doc_from_target in synchronizer, which
+                              implements the TAKE OTHER semantics.
+        :type insert_doc_cb: function
+
+        :param ensure_callback: A callback that ensures we know the target
+                                replica uid if the target replica was just
+                                created.
+        :type ensure_callback: function
+
+        :return: A deferred which fires with the new generation and
+                 transaction id of the target replica.
+        :rtype: twisted.internet.defer.Deferred
+        """
+        # ---------- phase 1: send docs to server ----------------------------
+        if DO_STATS:
+            self.sync_exchange_phase[0] += 1
+        # --------------------------------------------------------------------
+
+        self._ensure_callback = ensure_callback
+
+        if sync_id is None:
+            sync_id = str(uuid4())
+        self.source_replica_uid = source_replica_uid
+
+        # save a reference to the callback so we can use it after decrypting
+        self._insert_doc_cb = insert_doc_cb
+
+        gen_after_send, trans_id_after_send = yield self._send_docs(
+            docs_by_generation,
+            last_known_generation,
+            last_known_trans_id,
+            sync_id)
+
+        # ---------- phase 2: receive docs -----------------------------------
+        if DO_STATS:
+            self.sync_exchange_phase[0] += 1
+        # --------------------------------------------------------------------
+
+        cur_target_gen, cur_target_trans_id = yield self._receive_docs(
+            last_known_generation, last_known_trans_id,
+            ensure_callback, sync_id)
+
+        # update gen and trans id info in case we just sent and did not
+        # receive docs.
+        if gen_after_send is not None and gen_after_send > cur_target_gen:
+            cur_target_gen = gen_after_send
+            cur_target_trans_id = trans_id_after_send
+
+        # ---------- phase 3: sync exchange is over --------------------------
+        if DO_STATS:
+            self.sync_exchange_phase[0] += 1
+        # --------------------------------------------------------------------
+
+        defer.returnValue([cur_target_gen, cur_target_trans_id])
+
+
+def _unauth_to_invalid_token_error(failure):
+    """
+    An errback to translate unauthorized errors to our own invalid token
+    class.
+
+    :param failure: The original failure.
+    :type failure: twisted.python.failure.Failure
+
+    :return: Either the original failure or an invalid auth token error.
+    :rtype: twisted.python.failure.Failure
+    """
+    failure.trap(HTTPError)
+    if failure.value.status == 401:
+        raise InvalidAuthTokenError
+    return failure
diff --git a/src/leap/soledad/client/http_target/fetch.py b/src/leap/soledad/client/http_target/fetch.py
new file mode 100644
index 00000000..9d456830
--- /dev/null
+++ b/src/leap/soledad/client/http_target/fetch.py
@@ -0,0 +1,161 @@
+# -*- coding: utf-8 -*-
+# fetch.py
+# Copyright (C) 2015 LEAP
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+import json
+from twisted.internet import defer
+from twisted.internet import threads
+
+from leap.soledad.client.events import SOLEDAD_SYNC_RECEIVE_STATUS
+from leap.soledad.client.events import emit_async
+from leap.soledad.client.http_target.support import RequestBody
+from leap.soledad.common.log import getLogger
+from leap.soledad.client._crypto import is_symmetrically_encrypted
+from leap.soledad.common.l2db import errors
+from leap.soledad.client import crypto as old_crypto
+
+from .._document import Document
+from . import fetch_protocol
+
+logger = getLogger(__name__)
+
+
+class HTTPDocFetcher(object):
+    """
+    Handles Document fetching from Soledad server, using HTTP as transport.
+    Steps:
+    * Prepares metadata by asking server for one document
+    * Fetch the total on response and prepare to ask all remaining
+    * (async) Documents will come encrypted.
+              So we parse, decrypt and insert locally as they arrive.
+    """
+
+    # The uuid of the local replica.
+    # Any class inheriting from this one should provide a meaningful attribute
+    # if the sync status event is meant to be used somewhere else.
+
+    uuid = 'undefined'
+    userid = 'undefined'
+
+    @defer.inlineCallbacks
+    def _receive_docs(self, last_known_generation, last_known_trans_id,
+                      ensure_callback, sync_id):
+        new_generation = last_known_generation
+        new_transaction_id = last_known_trans_id
+        # Acts as a queue, ensuring line order on async processing
+        # as `self._insert_doc_cb` cant be run concurrently or out of order.
+        # DeferredSemaphore solves the concurrency and its implementation uses
+        # a queue, solving the ordering.
+        # FIXME: Find a proper solution to avoid surprises on Twisted changes
+        self.semaphore = defer.DeferredSemaphore(1)
+
+        metadata = yield self._fetch_all(
+            last_known_generation, last_known_trans_id,
+            sync_id)
+        number_of_changes, ngen, ntrans = self._parse_metadata(metadata)
+
+        # wait for pending inserts
+        yield self.semaphore.acquire()
+
+        if ngen:
+            new_generation = ngen
+            new_transaction_id = ntrans
+
+        defer.returnValue([new_generation, new_transaction_id])
+
+    def _fetch_all(self, last_known_generation,
+                   last_known_trans_id, sync_id):
+        # add remote replica metadata to the request
+        body = RequestBody(
+            last_known_generation=last_known_generation,
+            last_known_trans_id=last_known_trans_id,
+            sync_id=sync_id,
+            ensure=self._ensure_callback is not None)
+        self._received_docs = 0
+        # build a stream reader with _doc_parser as a callback
+        body_reader = fetch_protocol.build_body_reader(self._doc_parser)
+        # start download stream
+        return self._http_request(
+            self._url,
+            method='POST',
+            body=str(body),
+            content_type='application/x-soledad-sync-get',
+            body_reader=body_reader)
+
+    @defer.inlineCallbacks
+    def _doc_parser(self, doc_info, content, total):
+        """
+        Insert a received document into the local replica, decrypting
+        if necessary. The case where it's not decrypted is when a doc gets
+        inserted from Server side with a GPG encrypted content.
+
+        :param doc_info: Dictionary representing Document information.
+        :type doc_info: dict
+        :param content: The Document's content.
+        :type idx: str
+        :param total: The total number of operations.
+        :type total: int
+        """
+        yield self.semaphore.run(self.__atomic_doc_parse, doc_info, content,
+                                 total)
+
+    @defer.inlineCallbacks
+    def __atomic_doc_parse(self, doc_info, content, total):
+        doc = Document(doc_info['id'], doc_info['rev'], content)
+        if is_symmetrically_encrypted(content):
+            content = (yield self._crypto.decrypt_doc(doc)).getvalue()
+        elif old_crypto.is_symmetrically_encrypted(doc):
+            content = self._deprecated_crypto.decrypt_doc(doc)
+        doc.set_json(content)
+
+        # TODO insert blobs here on the blob backend
+        # FIXME: This is wrong. Using the very same SQLite connection object
+        # from multiple threads is dangerous. We should bring the dbpool here
+        # or find an alternative.  Deferring to a thread only helps releasing
+        # the reactor for other tasks as this is an IO intensive call.
+        yield threads.deferToThread(self._insert_doc_cb,
+                                    doc, doc_info['gen'], doc_info['trans_id'])
+        self._received_docs += 1
+        user_data = {'uuid': self.uuid, 'userid': self.userid}
+        _emit_receive_status(user_data, self._received_docs, total=total)
+
+    def _parse_metadata(self, metadata):
+        """
+        Parse the response from the server containing the sync metadata.
+
+        :param response: Metadata as string
+        :type response: str
+
+        :return: (number_of_changes, new_gen, new_trans_id)
+        :rtype: tuple
+        """
+        try:
+            metadata = json.loads(metadata)
+            # make sure we have replica_uid from fresh new dbs
+            if self._ensure_callback and 'replica_uid' in metadata:
+                self._ensure_callback(metadata['replica_uid'])
+            return (metadata['number_of_changes'], metadata['new_generation'],
+                    metadata['new_transaction_id'])
+        except (ValueError, KeyError):
+            raise errors.BrokenSyncStream('Metadata parsing failed')
+
+
+def _emit_receive_status(user_data, received_docs, total):
+    content = {'received': received_docs, 'total': total}
+    emit_async(SOLEDAD_SYNC_RECEIVE_STATUS, user_data, content)
+
+    if received_docs % 20 == 0:
+        msg = "%d/%d" % (received_docs, total)
+        logger.debug("Sync receive status: %s" % msg)
diff --git a/src/leap/soledad/client/http_target/fetch_protocol.py b/src/leap/soledad/client/http_target/fetch_protocol.py
new file mode 100644
index 00000000..851eb3a1
--- /dev/null
+++ b/src/leap/soledad/client/http_target/fetch_protocol.py
@@ -0,0 +1,157 @@
+# -*- coding: utf-8 -*-
+# fetch_protocol.py
+# Copyright (C) 2016 LEAP
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+import json
+from functools import partial
+from six import StringIO
+from twisted.web._newclient import ResponseDone
+from leap.soledad.common.l2db import errors
+from leap.soledad.common.l2db.remote import utils
+from leap.soledad.common.log import getLogger
+from .support import ReadBodyProtocol
+from .support import readBody
+
+logger = getLogger(__name__)
+
+
+class DocStreamReceiver(ReadBodyProtocol):
+    """
+    A protocol implementation that can parse incoming data from server based
+    on a line format specified on u1db implementation. Except that we split doc
+    attributes from content to ease parsing and increment throughput for larger
+    documents.
+    [\r\n
+    {metadata},\r\n
+    {doc_info},\r\n
+    {content},\r\n
+    ...
+    {doc_info},\r\n
+    {content},\r\n
+    ]
+    """
+
+    def __init__(self, response, deferred, doc_reader):
+        self.deferred = deferred
+        self.status = response.code if response else None
+        self.message = response.phrase if response else None
+        self.headers = response.headers if response else {}
+        self.delimiter = '\r\n'
+        self.metadata = ''
+        self._doc_reader = doc_reader
+        self.reset()
+
+    def reset(self):
+        self._line = 0
+        self._buffer = StringIO()
+        self._properly_finished = False
+
+    def connectionLost(self, reason):
+        """
+        Deliver the accumulated response bytes to the waiting L{Deferred}, if
+        the response body has been completely received without error.
+        """
+        if self.deferred.called:
+            return
+        try:
+            if reason.check(ResponseDone):
+                self.dataBuffer = self.metadata
+            else:
+                self.dataBuffer = self.finish()
+        except errors.BrokenSyncStream as e:
+            return self.deferred.errback(e)
+        return ReadBodyProtocol.connectionLost(self, reason)
+
+    def consumeBufferLines(self):
+        """
+        Consumes lines from buffer and rewind it, writing remaining data
+        that didn't formed a line back into buffer.
+        """
+        content = self._buffer.getvalue()[0:self._buffer.tell()]
+        self._buffer.seek(0)
+        lines = content.split(self.delimiter)
+        self._buffer.write(lines.pop(-1))
+        return lines
+
+    def dataReceived(self, data):
+        """
+        Buffer incoming data until a line breaks comes in. We check only
+        the incoming data for efficiency.
+        """
+        self._buffer.write(data)
+        if '\n' not in data:
+            return
+        lines = self.consumeBufferLines()
+        while lines:
+            line, _ = utils.check_and_strip_comma(lines.pop(0))
+            self.lineReceived(line)
+            self._line += 1
+
+    def lineReceived(self, line):
+        """
+        Protocol implementation.
+        0:      [\r\n
+        1:      {metadata},\r\n
+        (even): {doc_info},\r\n
+        (odd):  {data},\r\n
+        (last): ]
+        """
+        if self._properly_finished:
+            raise errors.BrokenSyncStream("Reading a finished stream")
+        if ']' == line:
+            self._properly_finished = True
+        elif self._line == 0:
+            if line is not '[':
+                raise errors.BrokenSyncStream("Invalid start")
+        elif self._line == 1:
+            self.metadata = line
+            if 'error' in self.metadata:
+                raise errors.BrokenSyncStream("Error from server: %s" % line)
+            self.total = json.loads(line).get('number_of_changes', -1)
+        elif (self._line % 2) == 0:
+            self.current_doc = json.loads(line)
+            if 'error' in self.current_doc:
+                raise errors.BrokenSyncStream("Error from server: %s" % line)
+        else:
+            d = self._doc_reader(
+                self.current_doc, line.strip() or None, self.total)
+            d.addErrback(self.deferred.errback)
+
+    def finish(self):
+        """
+        Checks that ']' came and stream was properly closed.
+        """
+        if not self._properly_finished:
+            raise errors.BrokenSyncStream('Stream not properly closed')
+        content = self._buffer.getvalue()[0:self._buffer.tell()]
+        self._buffer.close()
+        return content
+
+
+def build_body_reader(doc_reader):
+    """
+    Get the documents from a sync stream and call doc_reader on each
+    doc received.
+
+    @param doc_reader: Function to be called for processing an incoming doc.
+        Will be called with doc metadata (dict parsed from 1st line) and doc
+        content (string)
+    @type doc_reader: function
+
+    @return: A function that can be called by the http Agent to create and
+    configure the proper protocol.
+    """
+    protocolClass = partial(DocStreamReceiver, doc_reader=doc_reader)
+    return partial(readBody, protocolClass=protocolClass)
diff --git a/src/leap/soledad/client/http_target/send.py b/src/leap/soledad/client/http_target/send.py
new file mode 100644
index 00000000..2b286ec5
--- /dev/null
+++ b/src/leap/soledad/client/http_target/send.py
@@ -0,0 +1,107 @@
+# -*- coding: utf-8 -*-
+# send.py
+# Copyright (C) 2015 LEAP
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+import json
+
+from twisted.internet import defer
+
+from leap.soledad.common.log import getLogger
+from leap.soledad.client.events import emit_async
+from leap.soledad.client.events import SOLEDAD_SYNC_SEND_STATUS
+from leap.soledad.client.http_target.support import RequestBody
+from .send_protocol import DocStreamProducer
+
+logger = getLogger(__name__)
+
+
+class HTTPDocSender(object):
+    """
+    Handles Document uploading from Soledad server, using HTTP as transport.
+    They need to be encrypted and metadata prepared before sending.
+    """
+
+    # The uuid of the local replica.
+    # Any class inheriting from this one should provide a meaningful attribute
+    # if the sync status event is meant to be used somewhere else.
+
+    uuid = 'undefined'
+    userid = 'undefined'
+
+    @defer.inlineCallbacks
+    def _send_docs(self, docs_by_generation, last_known_generation,
+                   last_known_trans_id, sync_id):
+
+        if not docs_by_generation:
+            defer.returnValue([None, None])
+
+        # add remote replica metadata to the request
+        body = RequestBody(
+            last_known_generation=last_known_generation,
+            last_known_trans_id=last_known_trans_id,
+            sync_id=sync_id,
+            ensure=self._ensure_callback is not None)
+        result = yield self._send_batch(body, docs_by_generation)
+        response_dict = json.loads(result)[0]
+        gen_after_send = response_dict['new_generation']
+        trans_id_after_send = response_dict['new_transaction_id']
+        defer.returnValue([gen_after_send, trans_id_after_send])
+
+    @defer.inlineCallbacks
+    def _send_batch(self, body, docs):
+        total, calls = len(docs), []
+        for i, entry in enumerate(docs):
+            calls.append((self._prepare_one_doc,
+                         entry, body, i + 1, total))
+        result = yield self._send_request(body, calls)
+        _emit_send_status(self.uuid, body.consumed, total)
+
+        defer.returnValue(result)
+
+    def _send_request(self, body, calls):
+        return self._http_request(
+            self._url,
+            method='POST',
+            body=(body, calls),
+            content_type='application/x-soledad-sync-put',
+            body_producer=DocStreamProducer)
+
+    @defer.inlineCallbacks
+    def _prepare_one_doc(self, entry, body, idx, total):
+        get_doc_call, gen, trans_id = entry
+        doc, content = yield self._encrypt_doc(get_doc_call)
+        body.insert_info(
+            id=doc.doc_id, rev=doc.rev, content=content, gen=gen,
+            trans_id=trans_id, number_of_docs=total,
+            doc_idx=idx)
+        _emit_send_status(self.uuid, body.consumed, total)
+
+    @defer.inlineCallbacks
+    def _encrypt_doc(self, get_doc_call):
+        f, args, kwargs = get_doc_call
+        doc = yield f(*args, **kwargs)
+        if doc.is_tombstone():
+            defer.returnValue((doc, None))
+        else:
+            content = yield self._crypto.encrypt_doc(doc)
+            defer.returnValue((doc, content))
+
+
+def _emit_send_status(user_data, idx, total):
+    content = {'sent': idx, 'total': total}
+    emit_async(SOLEDAD_SYNC_SEND_STATUS, user_data, content)
+
+    msg = "%d/%d" % (idx, total)
+    logger.debug("Sync send status: %s" % msg)
diff --git a/src/leap/soledad/client/http_target/send_protocol.py b/src/leap/soledad/client/http_target/send_protocol.py
new file mode 100644
index 00000000..4941aa34
--- /dev/null
+++ b/src/leap/soledad/client/http_target/send_protocol.py
@@ -0,0 +1,75 @@
+# -*- coding: utf-8 -*-
+# send_protocol.py
+# Copyright (C) 2016 LEAP
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+from zope.interface import implementer
+from twisted.internet import defer
+from twisted.internet import reactor
+from twisted.web.iweb import IBodyProducer
+from twisted.web.iweb import UNKNOWN_LENGTH
+
+
+@implementer(IBodyProducer)
+class DocStreamProducer(object):
+    """
+    A producer that writes the body of a request to a consumer.
+    """
+
+    def __init__(self, producer):
+        """
+        Initialize the string produer.
+
+        :param producer: A RequestBody instance and a list of producer calls
+        :type producer: (.support.RequestBody, [(function, *args)])
+        """
+        self.body, self.producer = producer
+        self.length = UNKNOWN_LENGTH
+        self.pause = False
+        self.stop = False
+
+    @defer.inlineCallbacks
+    def startProducing(self, consumer):
+        """
+        Write the body to the consumer.
+
+        :param consumer: Any IConsumer provider.
+        :type consumer: twisted.internet.interfaces.IConsumer
+
+        :return: A Deferred that fires when production ends.
+        :rtype: twisted.internet.defer.Deferred
+        """
+        while self.producer and not self.stop:
+            if self.pause:
+                yield self.sleep(0.001)
+                continue
+            call = self.producer.pop(0)
+            fun, args = call[0], call[1:]
+            yield fun(*args)
+            consumer.write(self.body.pop(1, leave_open=True))
+        consumer.write(self.body.pop(0))  # close stream
+
+    def sleep(self, secs):
+        d = defer.Deferred()
+        reactor.callLater(secs, d.callback, None)
+        return d
+
+    def pauseProducing(self):
+        self.pause = True
+
+    def stopProducing(self):
+        self.stop = True
+
+    def resumeProducing(self):
+        self.pause = False
diff --git a/src/leap/soledad/client/http_target/support.py b/src/leap/soledad/client/http_target/support.py
new file mode 100644
index 00000000..d8d8e420
--- /dev/null
+++ b/src/leap/soledad/client/http_target/support.py
@@ -0,0 +1,220 @@
+# -*- coding: utf-8 -*-
+# support.py
+# Copyright (C) 2015 LEAP
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+import warnings
+import json
+
+from twisted.internet import defer
+from twisted.web.client import _ReadBodyProtocol
+from twisted.web.client import PartialDownloadError
+from twisted.web._newclient import ResponseDone
+from twisted.web._newclient import PotentialDataLoss
+
+from leap.soledad.common.l2db import errors
+from leap.soledad.common.l2db.remote import http_errors
+
+# we want to make sure that HTTP errors will raise appropriate u1db errors,
+# that is, fire errbacks with the appropriate failures, in the context of
+# twisted. Because of that, we redefine the http body reader used by the HTTP
+# client below.
+
+
+class ReadBodyProtocol(_ReadBodyProtocol):
+    """
+    From original Twisted implementation, focused on adding our error
+    handling and ensuring that the proper u1db error is raised.
+    """
+
+    def __init__(self, response, deferred):
+        """
+        Initialize the protocol, additionally storing the response headers.
+        """
+        _ReadBodyProtocol.__init__(
+            self, response.code, response.phrase, deferred)
+        self.headers = response.headers
+
+    # ---8<--- snippet from u1db.remote.http_client, modified to use errbacks
+    def _error(self, respdic):
+        descr = respdic.get("error")
+        exc_cls = errors.wire_description_to_exc.get(descr)
+        if exc_cls is not None:
+            message = respdic.get("message")
+            self.deferred.errback(exc_cls(message))
+        else:
+            self.deferred.errback(
+                errors.HTTPError(self.status, respdic, self.headers))
+    # ---8<--- end of snippet from u1db.remote.http_client
+
+    def connectionLost(self, reason):
+        """
+        Deliver the accumulated response bytes to the waiting L{Deferred}, if
+        the response body has been completely received without error.
+        """
+        if reason.check(ResponseDone):
+
+            body = b''.join(self.dataBuffer)
+
+            # ---8<--- snippet from u1db.remote.http_client
+            if self.status in (200, 201):
+                self.deferred.callback(body)
+            elif self.status in http_errors.ERROR_STATUSES:
+                try:
+                    respdic = json.loads(body)
+                except ValueError:
+                    self.deferred.errback(
+                        errors.HTTPError(self.status, body, self.headers))
+                else:
+                    self._error(respdic)
+            # special cases
+            elif self.status == 503:
+                self.deferred.errback(errors.Unavailable(body, self.headers))
+            else:
+                self.deferred.errback(
+                    errors.HTTPError(self.status, body, self.headers))
+            # ---8<--- end of snippet from u1db.remote.http_client
+
+        elif reason.check(PotentialDataLoss):
+            self.deferred.errback(
+                PartialDownloadError(self.status, self.message,
+                                     b''.join(self.dataBuffer)))
+        else:
+            self.deferred.errback(reason)
+
+
+def readBody(response, protocolClass=ReadBodyProtocol):
+    """
+    Get the body of an L{IResponse} and return it as a byte string.
+
+    This is a helper function for clients that don't want to incrementally
+    receive the body of an HTTP response.
+
+    @param response: The HTTP response for which the body will be read.
+    @type response: L{IResponse} provider
+
+    @return: A L{Deferred} which will fire with the body of the response.
+        Cancelling it will close the connection to the server immediately.
+    """
+    def cancel(deferred):
+        """
+        Cancel a L{readBody} call, close the connection to the HTTP server
+        immediately, if it is still open.
+
+        @param deferred: The cancelled L{defer.Deferred}.
+        """
+        abort = getAbort()
+        if abort is not None:
+            abort()
+
+    d = defer.Deferred(cancel)
+    protocol = protocolClass(response, d)
+
+    def getAbort():
+        return getattr(protocol.transport, 'abortConnection', None)
+
+    response.deliverBody(protocol)
+
+    if protocol.transport is not None and getAbort() is None:
+        warnings.warn(
+            'Using readBody with a transport that does not have an '
+            'abortConnection method',
+            category=DeprecationWarning,
+            stacklevel=2)
+
+    return d
+
+
+class RequestBody(object):
+    """
+    This class is a helper to generate send and fetch requests.
+    The expected format is something like:
+    [
+    {headers},
+    {entry1},
+    {...},
+    {entryN},
+    ]
+    """
+
+    def __init__(self, **header_dict):
+        """
+        Creates a new RequestBody holding header information.
+
+        :param header_dict: A dictionary with the headers.
+        :type header_dict: dict
+        """
+        self.headers = header_dict
+        self.entries = []
+        self.consumed = 0
+
+    def insert_info(self, **entry_dict):
+        """
+        Dumps an entry into JSON format and add it to entries list.
+        Adds 'content' key on a new line if it's present.
+
+        :param entry_dict: Entry as a dictionary
+        :type entry_dict: dict
+        """
+        content = ''
+        if 'content' in entry_dict:
+            content = ',\r\n' + (entry_dict['content'] or '')
+        entry = json.dumps(entry_dict) + content
+        self.entries.append(entry)
+
+    def pop(self, amount=10, leave_open=False):
+        """
+        Removes entries and returns it formatted and ready
+        to be sent.
+
+        :param amount: number of entries to pop and format
+        :type amount: int
+
+        :param leave_open: flag to skip stream closing
+        :type amount: bool
+
+        :return: formatted body ready to be sent
+        :rtype: str
+        """
+        start = self.consumed == 0
+        amount = min([len(self.entries), amount])
+        entries = [self.entries.pop(0) for i in xrange(amount)]
+        self.consumed += amount
+        end = len(self.entries) == 0 if not leave_open else False
+        return self.entries_to_str(entries, start, end)
+
+    def __str__(self):
+        return self.pop(len(self.entries))
+
+    def __len__(self):
+        return len(self.entries)
+
+    def entries_to_str(self, entries=None, start=True, end=True):
+        """
+        Format a list of entries into the body format expected
+        by the server.
+
+        :param entries: entries to format
+        :type entries: list
+
+        :return: formatted body ready to be sent
+        :rtype: str
+        """
+        data = ''
+        if start:
+            data = '[\r\n' + json.dumps(self.headers)
+        data += ''.join(',\r\n' + entry for entry in entries)
+        if end:
+            data += '\r\n]'
+        return data
diff --git a/src/leap/soledad/client/interfaces.py b/src/leap/soledad/client/interfaces.py
new file mode 100644
index 00000000..0600449f
--- /dev/null
+++ b/src/leap/soledad/client/interfaces.py
@@ -0,0 +1,368 @@
+# -*- coding: utf-8 -*-
+# interfaces.py
+# Copyright (C) 2014 LEAP
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+"""
+Interfaces used by the Soledad Client.
+"""
+from zope.interface import Interface, Attribute
+
+#
+# Plugins
+#
+
+
+class ISoledadPostSyncPlugin(Interface):
+    """
+    I implement the minimal methods and attributes for a plugin that can be
+    called after a soledad synchronization has ended.
+    """
+
+    def process_received_docs(self, doc_id_list):
+        """
+        Do something with the passed list of doc_ids received after the last
+        sync.
+
+        :param doc_id_list: a list of strings for the received doc_ids
+        """
+
+    watched_doc_types = Attribute("""
+        a tuple of the watched doc types for this plugin. So far, the
+        `doc-types` convention is just the preffix of the doc_id, which is
+        basically its first character, followed by a dash. So, for instance,
+        `M-` is used for meta-docs in mail, and `F-` is used for flag-docs in
+        mail. For now there's no central register of all the doc-types
+        used.""")
+
+
+#
+# Soledad storage
+#
+
+class ILocalStorage(Interface):
+    """
+    I implement core methods for the u1db local storage of documents and
+    indexes.
+    """
+    local_db_path = Attribute(
+        "The path for the local database replica")
+    local_db_file_name = Attribute(
+        "The name of the local SQLCipher U1DB database file")
+    uuid = Attribute("The user uuid")
+    default_prefix = Attribute(
+        "Prefix for default values for path")
+
+    def put_doc(self, doc):
+        """
+        Update a document in the local encrypted database.
+
+        :param doc: the document to update
+        :type doc: Document
+
+        :return:
+            a deferred that will fire with the new revision identifier for
+            the document
+        :rtype: Deferred
+        """
+
+    def delete_doc(self, doc):
+        """
+        Delete a document from the local encrypted database.
+
+        :param doc: the document to delete
+        :type doc: Document
+
+        :return:
+            a deferred that will fire with ...
+        :rtype: Deferred
+        """
+
+    def get_doc(self, doc_id, include_deleted=False):
+        """
+        Retrieve a document from the local encrypted database.
+
+        :param doc_id: the unique document identifier
+        :type doc_id: str
+        :param include_deleted:
+            if True, deleted documents will be returned with empty content;
+            otherwise asking for a deleted document will return None
+        :type include_deleted: bool
+
+        :return:
+            A deferred that will fire with the document object, containing a
+            Document, or None if it could not be found
+        :rtype: Deferred
+        """
+
+    def get_docs(self, doc_ids, check_for_conflicts=True,
+                 include_deleted=False):
+        """
+        Get the content for many documents.
+
+        :param doc_ids: a list of document identifiers
+        :type doc_ids: list
+        :param check_for_conflicts: if set False, then the conflict check will
+            be skipped, and 'None' will be returned instead of True/False
+        :type check_for_conflicts: bool
+
+        :return:
+            A deferred that will fire with an iterable giving the Document
+            object for each document id in matching doc_ids order.
+        :rtype: Deferred
+        """
+
+    def get_all_docs(self, include_deleted=False):
+        """
+        Get the JSON content for all documents in the database.
+
+        :param include_deleted: If set to True, deleted documents will be
+                                returned with empty content. Otherwise deleted
+                                documents will not be included in the results.
+        :return:
+            A deferred that will fire with (generation, [Document]): that is,
+            the current generation of the database, followed by a list of all
+            the documents in the database.
+        :rtype: Deferred
+        """
+
+    def create_doc(self, content, doc_id=None):
+        """
+        Create a new document in the local encrypted database.
+
+        :param content: the contents of the new document
+        :type content: dict
+        :param doc_id: an optional identifier specifying the document id
+        :type doc_id: str
+
+        :return:
+            A deferred tht will fire with the new document (Document
+            instance).
+        :rtype: Deferred
+        """
+
+    def create_doc_from_json(self, json, doc_id=None):
+        """
+        Create a new document.
+
+        You can optionally specify the document identifier, but the document
+        must not already exist. See 'put_doc' if you want to override an
+        existing document.
+        If the database specifies a maximum document size and the document
+        exceeds it, create will fail and raise a DocumentTooBig exception.
+
+        :param json: The JSON document string
+        :type json: str
+        :param doc_id: An optional identifier specifying the document id.
+        :type doc_id:
+        :return:
+            A deferred that will fire with the new document (A Document
+            instance)
+        :rtype: Deferred
+        """
+
+    def create_index(self, index_name, *index_expressions):
+        """
+        Create an named index, which can then be queried for future lookups.
+        Creating an index which already exists is not an error, and is cheap.
+        Creating an index which does not match the index_expressions of the
+        existing index is an error.
+        Creating an index will block until the expressions have been evaluated
+        and the index generated.
+
+        :param index_name: A unique name which can be used as a key prefix
+        :type index_name: str
+        :param index_expressions:
+            index expressions defining the index information.
+        :type index_expressions: dict
+
+            Examples:
+
+            "fieldname", or "fieldname.subfieldname" to index alphabetically
+            sorted on the contents of a field.
+
+            "number(fieldname, width)", "lower(fieldname)"
+        """
+
+    def delete_index(self, index_name):
+        """
+        Remove a named index.
+
+        :param index_name: The name of the index we are removing
+        :type index_name: str
+        """
+
+    def list_indexes(self):
+        """
+        List the definitions of all known indexes.
+
+        :return: A list of [('index-name', ['field', 'field2'])] definitions.
+        :rtype: Deferred
+        """
+
+    def get_from_index(self, index_name, *key_values):
+        """
+        Return documents that match the keys supplied.
+
+        You must supply exactly the same number of values as have been defined
+        in the index. It is possible to do a prefix match by using '*' to
+        indicate a wildcard match. You can only supply '*' to trailing entries,
+        (eg 'val', '*', '*' is allowed, but '*', 'val', 'val' is not.)
+        It is also possible to append a '*' to the last supplied value (eg
+        'val*', '*', '*' or 'val', 'val*', '*', but not 'val*', 'val', '*')
+
+        :param index_name: The index to query
+        :type index_name: str
+        :param key_values: values to match. eg, if you have
+                           an index with 3 fields then you would have:
+                           get_from_index(index_name, val1, val2, val3)
+        :type key_values: tuple
+        :return: List of [Document]
+        :rtype: list
+        """
+
+    def get_count_from_index(self, index_name, *key_values):
+        """
+        Return the count of the documents that match the keys and
+        values supplied.
+
+        :param index_name: The index to query
+        :type index_name: str
+        :param key_values: values to match. eg, if you have
+                           an index with 3 fields then you would have:
+                           get_from_index(index_name, val1, val2, val3)
+        :type key_values: tuple
+        :return: count.
+        :rtype: int
+        """
+
+    def get_range_from_index(self, index_name, start_value, end_value):
+        """
+        Return documents that fall within the specified range.
+
+        Both ends of the range are inclusive. For both start_value and
+        end_value, one must supply exactly the same number of values as have
+        been defined in the index, or pass None. In case of a single column
+        index, a string is accepted as an alternative for a tuple with a single
+        value. It is possible to do a prefix match by using '*' to indicate
+        a wildcard match. You can only supply '*' to trailing entries, (eg
+        'val', '*', '*' is allowed, but '*', 'val', 'val' is not.) It is also
+        possible to append a '*' to the last supplied value (eg 'val*', '*',
+        '*' or 'val', 'val*', '*', but not 'val*', 'val', '*')
+
+        :param index_name: The index to query
+        :type index_name: str
+        :param start_values: tuples of values that define the lower bound of
+            the range. eg, if you have an index with 3 fields then you would
+            have: (val1, val2, val3)
+        :type start_values: tuple
+        :param end_values: tuples of values that define the upper bound of the
+            range. eg, if you have an index with 3 fields then you would have:
+            (val1, val2, val3)
+        :type end_values: tuple
+        :return: A deferred that will fire with a list of [Document]
+        :rtype: Deferred
+        """
+
+    def get_index_keys(self, index_name):
+        """
+        Return all keys under which documents are indexed in this index.
+
+        :param index_name: The index to query
+        :type index_name: str
+        :return:
+            A deferred that will fire with a list of tuples of indexed keys.
+        :rtype: Deferred
+        """
+
+    def get_doc_conflicts(self, doc_id):
+        """
+        Get the list of conflicts for the given document.
+
+        :param doc_id: the document id
+        :type doc_id: str
+
+        :return:
+            A deferred that will fire with a list of the document entries that
+            are conflicted.
+        :rtype: Deferred
+        """
+
+    def resolve_doc(self, doc, conflicted_doc_revs):
+        """
+        Mark a document as no longer conflicted.
+
+        :param doc: a document with the new content to be inserted.
+        :type doc: Document
+        :param conflicted_doc_revs:
+            A deferred that will fire with a list of revisions that the new
+            content supersedes.
+        :type conflicted_doc_revs: list
+        """
+
+
+class ISyncableStorage(Interface):
+    """
+    I implement methods to synchronize with a remote replica.
+    """
+    replica_uid = Attribute("The uid of the local replica")
+    syncing = Attribute(
+        "Property, True if the syncer is syncing.")
+    token = Attribute("The authentication Token.")
+
+    def sync(self):
+        """
+        Synchronize the local encrypted replica with a remote replica.
+
+        This method blocks until a syncing lock is acquired, so there are no
+        attempts of concurrent syncs from the same client replica.
+
+        :param url: the url of the target replica to sync with
+        :type url: str
+
+        :return:
+            A deferred that will fire with the local generation before the
+            synchronisation was performed.
+        :rtype: str
+        """
+
+    def stop_sync(self):
+        """
+        Stop the current syncing process.
+        """
+
+
+class ISecretsStorage(Interface):
+    """
+    I implement methods needed for initializing and accessing secrets, that are
+    synced against the Shared Recovery Database.
+    """
+    secrets_file_name = Attribute(
+        "The name of the file where the storage secrets will be stored")
+
+    # XXX this used internally from secrets, so it might be good to preserve
+    # as a public boundary with other components.
+
+    # We should also probably document its interface.
+    secrets = Attribute("A SoledadSecrets object containing access to secrets")
+
+    def change_passphrase(self, new_passphrase):
+        """
+        Change the passphrase that encrypts the storage secret.
+
+        :param new_passphrase: The new passphrase.
+        :type new_passphrase: unicode
+
+        :raise NoStorageSecret: Raised if there's no storage secret available.
+        """
diff --git a/src/leap/soledad/client/shared_db.py b/src/leap/soledad/client/shared_db.py
new file mode 100644
index 00000000..4f70c74b
--- /dev/null
+++ b/src/leap/soledad/client/shared_db.py
@@ -0,0 +1,134 @@
+# -*- coding: utf-8 -*-
+# shared_db.py
+# Copyright (C) 2013 LEAP
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+"""
+A shared database for storing/retrieving encrypted key material.
+"""
+from leap.soledad.common.l2db.remote.http_database import HTTPDatabase
+
+from leap.soledad.client.auth import TokenBasedAuth
+
+
+# ----------------------------------------------------------------------------
+# Soledad shared database
+# ----------------------------------------------------------------------------
+
+# TODO could have a hierarchy of soledad exceptions.
+
+
+class NoTokenForAuth(Exception):
+    """
+    No token was found for token-based authentication.
+    """
+
+
+class Unauthorized(Exception):
+    """
+    User does not have authorization to perform task.
+    """
+
+
+class ImproperlyConfiguredError(Exception):
+    """
+    Wrong parameters in the database configuration.
+    """
+
+
+class SoledadSharedDatabase(HTTPDatabase, TokenBasedAuth):
+    """
+    This is a shared recovery database that enables users to store their
+    encryption secrets in the server and retrieve them afterwards.
+    """
+    # TODO: prevent client from messing with the shared DB.
+    # TODO: define and document API.
+
+    #
+    # Token auth methods.
+    #
+
+    def set_token_credentials(self, uuid, token):
+        """
+        Store given credentials so we can sign the request later.
+
+        :param uuid: The user's uuid.
+        :type uuid: str
+        :param token: The authentication token.
+        :type token: str
+        """
+        TokenBasedAuth.set_token_credentials(self, uuid, token)
+
+    def _sign_request(self, method, url_query, params):
+        """
+        Return an authorization header to be included in the HTTP request.
+
+        :param method: The HTTP method.
+        :type method: str
+        :param url_query: The URL query string.
+        :type url_query: str
+        :param params: A list with encoded query parameters.
+        :type param: list
+
+        :return: The Authorization header.
+        :rtype: list of tuple
+        """
+        return TokenBasedAuth._sign_request(self, method, url_query, params)
+
+    #
+    # Modified HTTPDatabase methods.
+    #
+
+    @staticmethod
+    def open_database(url, creds=None):
+        """
+        Open a Soledad shared database.
+
+        :param url: URL of the remote database.
+        :type url: str
+        :param creds: A tuple containing the authentication method and
+            credentials.
+        :type creds: tuple
+
+        :return: The shared database in the given url.
+        :rtype: SoledadSharedDatabase
+        """
+        db = SoledadSharedDatabase(url, creds=creds)
+        return db
+
+    @staticmethod
+    def delete_database(url):
+        """
+        Dummy method that prevents from deleting shared database.
+
+        :raise: This will always raise an Unauthorized exception.
+
+        :param url: The database URL.
+        :type url: str
+        """
+        raise Unauthorized("Can't delete shared database.")
+
+    def __init__(self, url, document_factory=None, creds=None):
+        """
+        Initialize database with auth token and encryption powers.
+
+        :param url: URL of the remote database.
+        :type url: str
+        :param document_factory: A factory for U1BD documents.
+        :type document_factory: u1db.Document
+        :param creds: A tuple containing the authentication method and
+            credentials.
+        :type creds: tuple
+        """
+        HTTPDatabase.__init__(self, url, document_factory, creds)
diff --git a/src/leap/soledad/client/sync.py b/src/leap/soledad/client/sync.py
new file mode 100644
index 00000000..2a927189
--- /dev/null
+++ b/src/leap/soledad/client/sync.py
@@ -0,0 +1,231 @@
+# -*- coding: utf-8 -*-
+# sync.py
+# Copyright (C) 2014 LEAP
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+"""
+Soledad synchronization utilities.
+"""
+import os
+
+from twisted.internet import defer
+
+from leap.soledad.common.log import getLogger
+from leap.soledad.common.l2db import errors
+from leap.soledad.common.l2db.sync import Synchronizer
+from leap.soledad.common.errors import BackendNotReadyError
+
+
+logger = getLogger(__name__)
+
+
+# we may want to collect statistics from the sync process
+DO_STATS = False
+if os.environ.get('SOLEDAD_STATS'):
+    DO_STATS = True
+
+
+class SoledadSynchronizer(Synchronizer):
+    """
+    Collect the state around synchronizing 2 U1DB replicas.
+
+    Synchronization is bi-directional, in that new items in the source are sent
+    to the target, and new items in the target are returned to the source.
+    However, it still recognizes that one side is initiating the request. Also,
+    at the moment, conflicts are only created in the source.
+
+    Also modified to allow for interrupting the synchronization process.
+    """
+    received_docs = []
+
+    def __init__(self, *args, **kwargs):
+        Synchronizer.__init__(self, *args, **kwargs)
+        if DO_STATS:
+            self.sync_phase = [0]
+            self.sync_exchange_phase = None
+
+    @defer.inlineCallbacks
+    def sync(self):
+        """
+        Synchronize documents between source and target.
+
+        :return: A deferred which will fire after the sync has finished with
+                 the local generation before the synchronization was performed.
+        :rtype: twisted.internet.defer.Deferred
+        """
+
+        sync_target = self.sync_target
+        self.received_docs = []
+
+        # ---------- phase 1: get sync info from server ----------------------
+        if DO_STATS:
+            self.sync_phase[0] += 1
+            self.sync_exchange_phase = self.sync_target.sync_exchange_phase
+        # --------------------------------------------------------------------
+
+        # get target identifier, its current generation,
+        # and its last-seen database generation for this source
+        ensure_callback = None
+        try:
+            (self.target_replica_uid, target_gen, target_trans_id,
+             target_my_gen, target_my_trans_id) = yield \
+                sync_target.get_sync_info(self.source._replica_uid)
+        except (errors.DatabaseDoesNotExist, BackendNotReadyError) as e:
+            logger.warn("Database isn't ready on server. Will be created.")
+            logger.warn("Reason: %s" % e.__class__)
+            self.target_replica_uid = None
+            target_gen, target_trans_id = 0, ''
+            target_my_gen, target_my_trans_id = 0, ''
+
+        logger.debug("target replica uid: %s" % self.target_replica_uid)
+        logger.debug("target generation: %d" % target_gen)
+        logger.debug("target trans id: %s" % target_trans_id)
+        logger.debug("target my gen: %d" % target_my_gen)
+        logger.debug("target my trans_id: %s" % target_my_trans_id)
+        logger.debug("source replica_uid: %s" % self.source._replica_uid)
+
+        # make sure we'll have access to target replica uid once it exists
+        if self.target_replica_uid is None:
+
+            def ensure_callback(replica_uid):
+                self.target_replica_uid = replica_uid
+
+        # make sure we're not syncing one replica with itself
+        if self.target_replica_uid == self.source._replica_uid:
+            raise errors.InvalidReplicaUID
+
+        # validate the info the target has about the source replica
+        self.source.validate_gen_and_trans_id(
+            target_my_gen, target_my_trans_id)
+
+        # ---------- phase 2: what's changed ---------------------------------
+        if DO_STATS:
+            self.sync_phase[0] += 1
+        # --------------------------------------------------------------------
+
+        # what's changed since that generation and this current gen
+        my_gen, _, changes = self.source.whats_changed(target_my_gen)
+        logger.debug("there are %d documents to send" % len(changes))
+
+        # get source last-seen database generation for the target
+        if self.target_replica_uid is None:
+            target_last_known_gen, target_last_known_trans_id = 0, ''
+        else:
+            target_last_known_gen, target_last_known_trans_id = \
+                self.source._get_replica_gen_and_trans_id(
+                    self.target_replica_uid)
+            logger.debug(
+                "last known target gen: %d" % target_last_known_gen)
+            logger.debug(
+                "last known target trans_id: %s" % target_last_known_trans_id)
+
+        # validate transaction ids
+        if not changes and target_last_known_gen == target_gen:
+            if target_trans_id != target_last_known_trans_id:
+                raise errors.InvalidTransactionId
+            defer.returnValue(my_gen)
+
+        # ---------- phase 3: sync exchange ----------------------------------
+        if DO_STATS:
+            self.sync_phase[0] += 1
+        # --------------------------------------------------------------------
+
+        docs_by_generation = self._docs_by_gen_from_changes(changes)
+
+        # exchange documents and try to insert the returned ones with
+        # the target, return target synced-up-to gen.
+        new_gen, new_trans_id = yield sync_target.sync_exchange(
+            docs_by_generation, self.source._replica_uid,
+            target_last_known_gen, target_last_known_trans_id,
+            self._insert_doc_from_target, ensure_callback=ensure_callback)
+        ids_sent = [doc_id for doc_id, _, _ in changes]
+        logger.debug("target gen after sync: %d" % new_gen)
+        logger.debug("target trans_id after sync: %s" % new_trans_id)
+        if hasattr(self.source, 'commit'):  # sqlcipher backend speed up
+            self.source.commit()  # insert it all in a single transaction
+        info = {
+            "target_replica_uid": self.target_replica_uid,
+            "new_gen": new_gen,
+            "new_trans_id": new_trans_id,
+            "my_gen": my_gen
+        }
+        self._syncing_info = info
+
+        # ---------- phase 4: complete sync ----------------------------------
+        if DO_STATS:
+            self.sync_phase[0] += 1
+        # --------------------------------------------------------------------
+
+        yield self.complete_sync()
+
+        _, _, changes = self.source.whats_changed(target_my_gen)
+        changed_doc_ids = [doc_id for doc_id, _, _ in changes]
+
+        just_received = list(set(changed_doc_ids) - set(ids_sent))
+        self.received_docs = just_received
+
+        # ---------- phase 5: sync is over -----------------------------------
+        if DO_STATS:
+            self.sync_phase[0] += 1
+        # --------------------------------------------------------------------
+
+        defer.returnValue(my_gen)
+
+    def _docs_by_gen_from_changes(self, changes):
+        docs_by_generation = []
+        kwargs = {'include_deleted': True}
+        for doc_id, gen, trans in changes:
+            get_doc = (self.source.get_doc, (doc_id,), kwargs)
+            docs_by_generation.append((get_doc, gen, trans))
+        return docs_by_generation
+
+    def complete_sync(self):
+        """
+        Last stage of the synchronization:
+            (a) record last known generation and transaction uid for the remote
+            replica, and
+            (b) make target aware of our current reached generation.
+
+        :return: A deferred which will fire when the sync has been completed.
+        :rtype: twisted.internet.defer.Deferred
+        """
+        logger.debug("completing deferred last step in sync...")
+
+        # record target synced-up-to generation including applying what we
+        # sent
+        info = self._syncing_info
+        self.source._set_replica_gen_and_trans_id(
+            info["target_replica_uid"], info["new_gen"], info["new_trans_id"])
+
+        # if gapless record current reached generation with target
+        return self._record_sync_info_with_the_target(info["my_gen"])
+
+    def _record_sync_info_with_the_target(self, start_generation):
+        """
+        Store local replica metadata in server.
+
+        :param start_generation: The local generation when the sync was
+                                 started.
+        :type start_generation: int
+
+        :return: A deferred which will fire when the operation has been
+                 completed.
+        :rtype: twisted.internet.defer.Deferred
+        """
+        cur_gen, trans_id = self.source._get_generation_info()
+        if (cur_gen == start_generation + self.num_inserted and
+                self.num_inserted > 0):
+            return self.sync_target.record_sync_info(
+                self.source._replica_uid, cur_gen, trans_id)
+        return defer.succeed(None)