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authorKali Kaneko <kali@leap.se>2016-09-16 19:24:55 -0400
committerdrebs <drebs@leap.se>2016-12-12 09:11:59 -0200
commit510c0ba3a0c0ade334090a1c36dab9ccae0ba1b4 (patch)
treedf0f2b8e285fa882eefed919d58d98b7aad3e03a /client/src/leap/soledad
parentfcf3b3046dd2005992638ebf993d53897af8ed3a (diff)
[feature] blob encryptor / decryptor
Diffstat (limited to 'client/src/leap/soledad')
-rw-r--r--client/src/leap/soledad/client/_crypto.py316
-rw-r--r--client/src/leap/soledad/client/api.py8
2 files changed, 217 insertions, 107 deletions
diff --git a/client/src/leap/soledad/client/_crypto.py b/client/src/leap/soledad/client/_crypto.py
index ed861fdd..61a190c7 100644
--- a/client/src/leap/soledad/client/_crypto.py
+++ b/client/src/leap/soledad/client/_crypto.py
@@ -24,9 +24,14 @@ import base64
import hashlib
import hmac
import os
+import struct
+import time
+from io import BytesIO
from cStringIO import StringIO
+import six
+
from twisted.internet import defer
from twisted.internet import interfaces
from twisted.internet import reactor
@@ -35,6 +40,9 @@ from twisted.persisted import dirdbm
from twisted.web import client
from twisted.web.client import FileBodyProducer
+from cryptography.exceptions import InvalidSignature
+from cryptography.hazmat.primitives import hashes
+from cryptography.hazmat.primitives.hmac import HMAC
from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
from cryptography.hazmat.backends.multibackend import MultiBackend
from cryptography.hazmat.backends.openssl.backend \
@@ -53,63 +61,223 @@ MAC_KEY_LENGTH = 64
crypto_backend = MultiBackend([OpenSSLBackend()])
-class EncryptionError(Exception):
+class ENC_SCHEME:
+ symkey = 1
+
+
+class ENC_METHOD:
+ aes_256_ctr = 1
+
+
+class EncryptionDecryptionError(Exception):
pass
-class AESWriter(object):
+class InvalidBlob(Exception):
+ pass
- implements(interfaces.IConsumer)
- def __init__(self, key, fd, iv=None):
+
+class BlobEncryptor(object):
+
+ """
+ Encrypts a payload associated with a given Document.
+ """
+
+ def __init__(self, doc_info, content_fd, result=None, secret=None, iv=None):
+
if iv is None:
iv = os.urandom(16)
+ else:
+ log.warn('Using a fixed IV. Use only for testing!')
+ self.iv = iv
+ if not secret:
+ raise EncryptionDecryptionError('no secret given')
+
+ self.doc_id = doc_info.doc_id
+ self.rev = doc_info.rev
+
+ self._producer = FileBodyProducer(content_fd, readSize=2**8)
+
+ self._preamble = BytesIO()
+ if result is None:
+ result = BytesIO()
+ self.result = result
+
+ sym_key = _get_sym_key_for_doc(doc_info.doc_id, secret)
+ mac_key = _get_mac_key_for_doc(doc_info.doc_id, secret)
+
+ self._aes_fd = BytesIO()
+ self._aes = AESEncryptor(sym_key, self.iv, self._aes_fd)
+ self._hmac = HMACWriter(mac_key)
+ self._write_preamble()
+
+ self._crypter = VerifiedEncrypter(self._aes, self._hmac)
+
+ def encrypt(self):
+ d = self._producer.startProducing(self._crypter)
+ d.addCallback(self._end_crypto_stream)
+ return d
+
+ def _write_preamble(self):
+
+ def write(data):
+ self._preamble.write(data)
+ self._hmac.write(data)
+
+ current_time = int(time.time())
+
+ write(b'\x80')
+ write(struct.pack(
+ 'Qbb',
+ current_time,
+ ENC_SCHEME.symkey,
+ ENC_METHOD.aes_256_ctr))
+ write(self.iv)
+ write(self.doc_id)
+ write(self.rev)
+
+ def _end_crypto_stream(self, ignored):
+ self._aes.end()
+ self._hmac.end()
+
+ preamble = self._preamble.getvalue()
+ encrypted = self._aes_fd.getvalue()
+ hmac = self._hmac.result.getvalue()
+
+ self.result.write(
+ base64.urlsafe_b64encode(preamble + encrypted + hmac))
+ self._preamble.close()
+ self._aes_fd.close()
+ self._hmac.result.close()
+ self.result.seek(0)
+ return defer.succeed('ok')
+
+
+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 HMAC doesn't verify.
+ """
+
+ def __init__(self, doc_info, ciphertext_fd, result=None,
+ secret=None):
+ self.doc_id = doc_info.doc_id
+ self.rev = doc_info.rev
+
+ self.ciphertext = ciphertext_fd
+
+ self.sym_key = _get_sym_key_for_doc(doc_info.doc_id, secret)
+ self.mac_key = _get_mac_key_for_doc(doc_info.doc_id, secret)
+
+ if result is None:
+ result = BytesIO()
+ self.result = result
+
+ def decrypt(self):
+
+ try:
+ data = base64.urlsafe_b64decode(self.ciphertext.getvalue())
+ except (TypeError, binascii.Error):
+ raise InvalidBlob
+ self.ciphertext.close()
+
+ current_time = int(time.time())
+ if not data or six.indexbytes(data, 0) != 0x80:
+ raise InvalidBlob
+ try:
+ ts, sch, meth = struct.unpack("Qbb", data[1:11])
+ except struct.error:
+ raise InvalidBlob
+
+ # TODO check timestamp
+ if sch != ENC_SCHEME.symkey:
+ raise InvalidBlob('invalid scheme')
+ # TODO should adapt the assymetric-gpg too, rigth?
+ if meth != ENC_METHOD.aes_256_ctr:
+ raise InvalidBlob('invalid encryption scheme')
+
+ iv = data[11:27]
+ docidlen = len(self.doc_id)
+ ciph_idx = 26 + docidlen
+ doc_id = data[26:ciph_idx]
+ revlen = len(self.rev)
+ rev_idx = ciph_idx + 1 + revlen
+ rev = data[ciph_idx + 1:rev_idx]
+
+ if rev != self.rev:
+ raise InvalidBlob('invalid revision')
+
+ ciphertext = data[rev_idx:-64]
+ hmac = data[-64:]
+
+ h = HMAC(self.mac_key, hashes.SHA512(), backend=crypto_backend)
+ h.update(data[:-64])
+ try:
+ h.verify(hmac)
+ except InvalidSignature:
+ raise InvalidBlob('HMAC could not be verifed')
+
+ decryptor = _get_aes_ctr_cipher(self.sym_key, iv).decryptor()
+
+ # TODO pass chunks, streaming, instead
+ # Use AESDecryptor below
+ self.result.write(decryptor.update(ciphertext))
+ self.result.write(decryptor.finalize())
+ return self.result
+
+
+class AESEncryptor(object):
+
+ implements(interfaces.IConsumer)
+
+ def __init__(self, key, iv, fd=None):
if len(key) != 32:
- raise EncryptionError('key is not 256 bits')
+ raise EncryptionDecryptionError('key is not 256 bits')
if len(iv) != 16:
- raise EncryptionError('iv is not 128 bits')
+ raise EncryptionDecryptionError('iv is not 128 bits')
cipher = _get_aes_ctr_cipher(key, iv)
self.encryptor = cipher.encryptor()
-
+
+ if fd is None:
+ fd = BytesIO()
self.fd = fd
+
self.done = False
- self.deferred = defer.Deferred()
def write(self, data):
encrypted = self.encryptor.update(data)
+ encode = binascii.b2a_hex
self.fd.write(encrypted)
return encrypted
def end(self):
if not self.done:
- self.encryptor.finalize()
- self.deferred.callback(self.fd)
+ final = self.encryptor.finalize()
self.done = True
class HMACWriter(object):
implements(interfaces.IConsumer)
+ hashtype = 'sha512'
def __init__(self, key):
- self.done = False
- self.deferred = defer.Deferred()
-
- self.digest = ''
- self._hmac = hmac.new(key, '', hashlib.sha256)
+ self._hmac = hmac.new(key, '', getattr(hashlib, self.hashtype))
+ self.result = BytesIO('')
def write(self, data):
self._hmac.update(data)
def end(self):
- if not self.done:
- self.digest = self._hmac.digest()
- self.deferred.callback(self.digest)
- self.done = True
+ self.result.write(self._hmac.digest())
+
-class EncryptAndHMAC(object):
+class VerifiedEncrypter(object):
implements(interfaces.IConsumer)
@@ -122,99 +290,39 @@ class EncryptAndHMAC(object):
self.hmac.write(enc_chunk)
+class AESDecryptor(object):
-class DocEncrypter(object):
-
- staging_path = os.path.join(get_path_prefix(), 'leap', 'soledad', 'staging')
- staged_template = """{"_enc_scheme": "symkey", "_enc_method":
- "aes-256-ctr", "_mac_method": "hmac", "_mac_hash": "sha256",
- "_encoding": "ENCODING", "_enc_json": "CIPHERTEXT", "_enc_iv": "IV", "_mac": "MAC"}"""
-
-
- def __init__(self, content_fd, doc_id, rev, secret=None):
- self._content_fd = content_fd
- self._contentFileProducer = FileBodyProducer(
- content_fd, readSize=2**8)
- self.doc_id = doc_id
- self.rev = rev
- self._encrypted_fd = StringIO()
-
- self.iv = os.urandom(16)
-
- sym_key = _get_sym_key_for_doc(doc_id, secret)
- mac_key = _get_mac_key_for_doc(doc_id, secret)
+ implements(interfaces.IConsumer)
- crypter = AESWriter(sym_key, self._encrypted_fd, self.iv)
- hmac = HMACWriter(mac_key)
+ def __init__(self, key, iv, fd):
+ if iv is None:
+ iv = os.urandom(16)
+ if len(key) != 32:
+ raise EncryptionhDecryptionError('key is not 256 bits')
+ if len(iv) != 16:
+ raise EncryptionDecryptionError('iv is not 128 bits')
- self.crypter_consumer = crypter
- self.hmac_consumer = hmac
+ cipher = _get_aes_ctr_cipher(key, iv)
+ self.decryptor = cipher.decryptor()
- self._prime_hmac()
- self.encrypt_and_mac_consumer = EncryptAndHMAC(crypter, hmac)
+ self.fd = fd
+ self.done = False
+ self.deferred = defer.Deferred()
- def encrypt_stream(self):
- d = self._contentFileProducer.startProducing(
- self.encrypt_and_mac_consumer)
- d.addCallback(self.end_crypto_stream)
- d.addCallback(self.persist_encrypted_doc)
- return d
- def end_crypto_stream(self, ignored):
- self.crypter_consumer.end()
- self._post_hmac()
- self.hmac_consumer.end()
- return defer.succeed('ok')
+ def write(self, data):
+ decrypted = self.decryptor.update(data)
+ self.fd.write(decrypted)
+ return decrypted
- # TODO make this pluggable:
- # pass another class (CryptoSerializer) to which we pass
- # the doc info, the encrypted_fd and the mac_digest
+ def end(self):
+ if not self.done:
+ self.decryptor.finalize()
+ self.deferred.callback(self.fd)
+ self.done = True
- def persist_encrypted_doc(self, ignored, encoding='hex'):
- # TODO -- transition to b64: needs migration FIXME
- if encoding == 'b64':
- encode = binascii.b2a_base64
- elif encoding == 'hex':
- encode = binascii.b2a_hex
- else:
- raise RuntimeError('Unknown encoding: %s' % encoding)
-
- # TODO to avoid blocking on io, this can use a
- # version of dbm that chunks the writes to the
- # disk fd by using the same FileBodyProducer strategy
- # that we're using here, long live to the Cooperator.
-
-
- db = dirdbm.DirDBM(self.staging_path)
- key = '{doc_id}@{rev}'.format(
- doc_id=self.doc_id, rev=self.rev)
- ciphertext = encode(self._encrypted_fd.getvalue())
- value = self.staged_template.replace(
- 'ENCODING', encoding).replace(
- 'CIPHERTEXT', ciphertext).replace(
- 'IV', encode(self.iv)).replace(
- 'MAC', encode(self.hmac_consumer.digest)).replace(
- '\n', '')
- self._encrypted_fd.seek(0)
-
- log.debug('persisting %s' % key)
- db[key] = value
-
- self._content_fd.close()
- self._encrypted_fd.close()
-
- def _prime_hmac(self):
- pre = '{doc_id}{rev}'.format(
- doc_id=self.doc_id, rev=self.rev)
- self.hmac_consumer.write(pre)
-
- def _post_hmac(self):
- post = '{enc_scheme}{enc_method}{enc_iv}'.format(
- enc_scheme='symkey',
- enc_method='aes-256-ctr',
- enc_iv=binascii.b2a_hex(self.iv))
- self.hmac_consumer.write(post)
+# utils
def _hmac_sha256(key, data):
diff --git a/client/src/leap/soledad/client/api.py b/client/src/leap/soledad/client/api.py
index 6b257669..98613df2 100644
--- a/client/src/leap/soledad/client/api.py
+++ b/client/src/leap/soledad/client/api.py
@@ -61,7 +61,7 @@ from leap.soledad.client.secrets import SoledadSecrets
from leap.soledad.client.shared_db import SoledadSharedDatabase
from leap.soledad.client import sqlcipher
from leap.soledad.client import encdecpool
-from leap.soledad.client._crypto import DocEncrypter
+#from leap.soledad.client._crypto import DocEncrypter
logger = getLogger(__name__)
@@ -360,8 +360,10 @@ class Soledad(object):
contentfd.seek(0)
sikret = self._secrets.remote_storage_secret
- crypter = DocEncrypter(
- contentfd, doc.doc_id, doc.rev, secret=sikret)
+
+ # TODO use BlobEncrypter
+ #crypter = DocEncrypter(
+ #contentfd, doc.doc_id, doc.rev, secret=sikret)
d = crypter.encrypt_stream()
d.addCallback(lambda _: result)
return d