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Diffstat (limited to 'src/leap/soledad/backends/leap_backend.py')
| -rw-r--r-- | src/leap/soledad/backends/leap_backend.py | 546 |
1 files changed, 0 insertions, 546 deletions
diff --git a/src/leap/soledad/backends/leap_backend.py b/src/leap/soledad/backends/leap_backend.py deleted file mode 100644 index d92025db..00000000 --- a/src/leap/soledad/backends/leap_backend.py +++ /dev/null @@ -1,546 +0,0 @@ -# -*- coding: utf-8 -*- -# leap_backend.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 U1DB backend for encrypting data before sending to server and decrypting -after receiving. -""" - -import simplejson as json -import hashlib -import hmac -import binascii - - -from u1db import Document -from u1db.remote import utils -from u1db.errors import BrokenSyncStream -from u1db.remote.http_target import HTTPSyncTarget - - -from leap.common.crypto import ( - EncryptionMethods, - UnknownEncryptionMethod, - encrypt_sym, - decrypt_sym, -) -from leap.common.check import leap_assert -from leap.soledad.auth import TokenBasedAuth - - -# -# Exceptions -# - -class DocumentNotEncrypted(Exception): - """ - Raised for failures in document encryption. - """ - pass - - -class UnknownEncryptionScheme(Exception): - """ - Raised when trying to decrypt from unknown encryption schemes. - """ - pass - - -class UnknownMacMethod(Exception): - """ - Raised when trying to authenticate document's content with unknown MAC - mehtod. - """ - pass - - -class WrongMac(Exception): - """ - Raised when failing to authenticate document's contents based on MAC. - """ - - -# -# Encryption schemes used for encryption. -# - -class EncryptionSchemes(object): - """ - Representation of encryption schemes used to encrypt documents. - """ - - NONE = 'none' - SYMKEY = 'symkey' - PUBKEY = 'pubkey' - - -class MacMethods(object): - """ - Representation of MAC methods used to authenticate document's contents. - """ - - HMAC = 'hmac' - - -# -# Crypto utilities for a LeapDocument. -# - -ENC_JSON_KEY = '_enc_json' -ENC_SCHEME_KEY = '_enc_scheme' -ENC_METHOD_KEY = '_enc_method' -ENC_IV_KEY = '_enc_iv' -MAC_KEY = '_mac' -MAC_METHOD_KEY = '_mac_method' - - -def mac_doc(crypto, doc_id, doc_rev, ciphertext, mac_method): - """ - 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 crypto: A SoledadCryto instance used to perform the encryption. - @type crypto: leap.soledad.crypto.SoledadCrypto - @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 mac_method: The MAC method to use. - @type mac_method: str - - @return: The calculated MAC. - @rtype: str - """ - if mac_method == MacMethods.HMAC: - return hmac.new( - crypto.doc_mac_key(doc_id), - str(doc_id) + str(doc_rev) + ciphertext, - hashlib.sha256).digest() - # raise if we do not know how to handle this MAC method - raise UnknownMacMethod('Unknown MAC method: %s.' % mac_method) - - -def encrypt_doc(crypto, doc): - """ - Encrypt C{doc}'s content. - - Encrypt doc's contents using AES-256 CTR mode and return a valid JSON - string representing the following: - - { - ENC_JSON_KEY: '<encrypted doc JSON string>', - ENC_SCHEME_KEY: 'symkey', - ENC_METHOD_KEY: EncryptionMethods.AES_256_CTR, - ENC_IV_KEY: '<the initial value used to encrypt>', - MAC_KEY: '<mac>' - MAC_METHOD_KEY: 'hmac' - } - - @param crypto: A SoledadCryto instance used to perform the encryption. - @type crypto: leap.soledad.crypto.SoledadCrypto - @param doc: The document with contents to be encrypted. - @type doc: LeapDocument - - @return: The JSON serialization of the dict representing the encrypted - content. - @rtype: str - """ - leap_assert(doc.is_tombstone() is False) - # encrypt content using AES-256 CTR mode - iv, ciphertext = encrypt_sym( - doc.get_json(), - crypto.doc_passphrase(doc.doc_id), - method=EncryptionMethods.AES_256_CTR) - # 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) - return json.dumps({ - ENC_JSON_KEY: hex_ciphertext, - ENC_SCHEME_KEY: EncryptionSchemes.SYMKEY, - ENC_METHOD_KEY: EncryptionMethods.AES_256_CTR, - ENC_IV_KEY: iv, - MAC_KEY: binascii.b2a_hex(mac_doc( # store the mac as hex. - crypto, doc.doc_id, doc.rev, - ciphertext, - MacMethods.HMAC)), - MAC_METHOD_KEY: MacMethods.HMAC, - }) - - -def decrypt_doc(crypto, doc): - """ - Decrypt C{doc}'s content. - - Return the JSON string representation of the document's decrypted content. - - The content of the document should have the following structure: - - { - ENC_JSON_KEY: '<enc_blob>', - ENC_SCHEME_KEY: '<enc_scheme>', - ENC_METHOD_KEY: '<enc_method>', - ENC_IV_KEY: '<initial value used to encrypt>', # (optional) - MAC_KEY: '<mac>' - 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 - EncryptionSchemes.SYMKEY and C{enc_method} is - EncryptionMethods.AES_256_CTR. - - @param crypto: A SoledadCryto instance to perform the encryption. - @type crypto: leap.soledad.crypto.SoledadCrypto - @param doc: The document to be decrypted. - @type doc: LeapDocument - - @return: The JSON serialization of the decrypted content. - @rtype: str - """ - leap_assert(doc.is_tombstone() is False) - leap_assert(ENC_JSON_KEY in doc.content) - leap_assert(ENC_SCHEME_KEY in doc.content) - leap_assert(ENC_METHOD_KEY in doc.content) - leap_assert(MAC_KEY in doc.content) - leap_assert(MAC_METHOD_KEY in doc.content) - # verify MAC - ciphertext = binascii.a2b_hex( # content is stored as hex. - doc.content[ENC_JSON_KEY]) - mac = mac_doc( - crypto, doc.doc_id, doc.rev, - ciphertext, - doc.content[MAC_METHOD_KEY]) - if binascii.a2b_hex(doc.content[MAC_KEY]) != mac: # mac is stored as hex. - raise WrongMac('Could not authenticate document\'s contents.') - # decrypt doc's content - enc_scheme = doc.content[ENC_SCHEME_KEY] - plainjson = None - if enc_scheme == EncryptionSchemes.SYMKEY: - enc_method = doc.content[ENC_METHOD_KEY] - if enc_method == EncryptionMethods.AES_256_CTR: - leap_assert(ENC_IV_KEY in doc.content) - plainjson = decrypt_sym( - ciphertext, - crypto.doc_passphrase(doc.doc_id), - method=enc_method, - iv=doc.content[ENC_IV_KEY]) - else: - raise UnknownEncryptionMethod(enc_method) - else: - raise UnknownEncryptionScheme(enc_scheme) - return plainjson - - -class LeapDocument(Document): - """ - Encryptable and syncable document. - - LEAP Documents can be flagged as syncable or not, so the replicas - might not sync every document. - """ - - def __init__(self, doc_id=None, rev=None, json='{}', has_conflicts=False, - syncable=True): - """ - Container for handling an encryptable document. - - @param doc_id: The unique document identifier. - @type doc_id: str - @param rev: The revision identifier of the document. - @type rev: str - @param json: The JSON string for this document. - @type json: str - @param has_conflicts: Boolean indicating if this document has conflicts - @type has_conflicts: bool - @param syncable: Should this document be synced with remote replicas? - @type syncable: bool - """ - Document.__init__(self, doc_id, rev, json, has_conflicts) - self._syncable = syncable - - def _get_syncable(self): - """ - Return whether this document is syncable. - - @return: Is this document syncable? - @rtype: bool - """ - return self._syncable - - def _set_syncable(self, syncable=True): - """ - Determine if this document should be synced with remote replicas. - - @param syncable: Should this document be synced with remote replicas? - @type syncable: bool - """ - self._syncable = syncable - - syncable = property( - _get_syncable, - _set_syncable, - doc="Determine if document should be synced with server." - ) - - def _get_rev(self): - """ - Get the document revision. - - Returning the revision as string solves the following exception in - Twisted web: - exceptions.TypeError: Can only pass-through bytes on Python 2 - - @return: The document revision. - @rtype: str - """ - if self._rev is None: - return None - return str(self._rev) - - def _set_rev(self, rev): - """ - Set document revision. - - @param rev: The new document revision. - @type rev: bytes - """ - self._rev = rev - - rev = property( - _get_rev, - _set_rev, - doc="Wrapper to ensure `doc.rev` is always returned as bytes.") - - -# -# LeapSyncTarget -# - -class LeapSyncTarget(HTTPSyncTarget, TokenBasedAuth): - """ - A SyncTarget that encrypts data before sending and decrypts data after - receiving. - """ - - # - # 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 HTTPSyncTarget methods. - # - - @staticmethod - def connect(url, crypto=None): - return LeapSyncTarget(url, crypto=crypto) - - def __init__(self, url, creds=None, crypto=None): - """ - Initialize the LeapSyncTarget. - - @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 - @param soledad: An instance of Soledad so we can encrypt/decrypt - document contents when syncing. - @type soledad: soledad.Soledad - """ - HTTPSyncTarget.__init__(self, url, creds) - self._crypto = crypto - - def _parse_sync_stream(self, data, return_doc_cb, ensure_callback=None): - """ - Parse incoming synchronization stream and insert documents in the - local database. - - If an incoming document's encryption scheme is equal to - EncryptionSchemes.SYMKEY, then this method will decrypt it with - Soledad's symmetric key. - - @param data: The body of the HTTP response. - @type data: str - @param return_doc_cb: A callback to insert docs from target. - @type return_doc_cb: function - @param ensure_callback: A callback to ensure we have the correct - target_replica_uid, if it was just created. - @type ensure_callback: function - - @raise BrokenSyncStream: If C{data} is malformed. - - @return: A dictionary representing the first line of the response got - from remote replica. - @rtype: list of str - """ - parts = data.splitlines() # one at a time - if not parts or parts[0] != '[': - raise BrokenSyncStream - data = parts[1:-1] - comma = False - if data: - line, comma = utils.check_and_strip_comma(data[0]) - res = json.loads(line) - if ensure_callback and 'replica_uid' in res: - ensure_callback(res['replica_uid']) - for entry in data[1:]: - if not comma: # missing in between comma - raise BrokenSyncStream - line, comma = utils.check_and_strip_comma(entry) - entry = json.loads(line) - #------------------------------------------------------------- - # symmetric decryption of document's contents - #------------------------------------------------------------- - # if arriving content was symmetrically encrypted, we decrypt - # it. - doc = LeapDocument(entry['id'], entry['rev'], entry['content']) - if doc.content and ENC_SCHEME_KEY in doc.content: - if doc.content[ENC_SCHEME_KEY] == \ - EncryptionSchemes.SYMKEY: - doc.set_json(decrypt_doc(self._crypto, doc)) - #------------------------------------------------------------- - # end of symmetric decryption - #------------------------------------------------------------- - return_doc_cb(doc, entry['gen'], entry['trans_id']) - if parts[-1] != ']': - try: - partdic = json.loads(parts[-1]) - except ValueError: - pass - else: - if isinstance(partdic, dict): - self._error(partdic) - raise BrokenSyncStream - if not data or comma: # no entries or bad extra comma - raise BrokenSyncStream - return res - - def sync_exchange(self, docs_by_generations, source_replica_uid, - last_known_generation, last_known_trans_id, - return_doc_cb, ensure_callback=None): - """ - Find out which documents the remote database does not know about, - encrypt and send them. - - This does the same as the parent's method but encrypts content before - syncing. - - @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 return_doc_cb: A callback for inserting received documents from - target. - @type return_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: The new generation and transaction id of the target replica. - @rtype: tuple - """ - self._ensure_connection() - if self._trace_hook: # for tests - self._trace_hook('sync_exchange') - url = '%s/sync-from/%s' % (self._url.path, source_replica_uid) - self._conn.putrequest('POST', url) - self._conn.putheader('content-type', 'application/x-u1db-sync-stream') - for header_name, header_value in self._sign_request('POST', url, {}): - self._conn.putheader(header_name, header_value) - entries = ['['] - size = 1 - - def prepare(**dic): - entry = comma + '\r\n' + json.dumps(dic) - entries.append(entry) - return len(entry) - - comma = '' - size += prepare( - last_known_generation=last_known_generation, - last_known_trans_id=last_known_trans_id, - ensure=ensure_callback is not None) - comma = ',' - for doc, gen, trans_id in docs_by_generations: - # skip non-syncable docs - if isinstance(doc, LeapDocument) and not doc.syncable: - continue - #------------------------------------------------------------- - # symmetric encryption of document's contents - #------------------------------------------------------------- - doc_json = doc.get_json() - if not doc.is_tombstone(): - doc_json = encrypt_doc(self._crypto, doc) - #------------------------------------------------------------- - # end of symmetric encryption - #------------------------------------------------------------- - size += prepare(id=doc.doc_id, rev=doc.rev, - content=doc_json, - gen=gen, trans_id=trans_id) - entries.append('\r\n]') - size += len(entries[-1]) - self._conn.putheader('content-length', str(size)) - self._conn.endheaders() - for entry in entries: - self._conn.send(entry) - entries = None - data, _ = self._response() - res = self._parse_sync_stream(data, return_doc_cb, ensure_callback) - data = None - return res['new_generation'], res['new_transaction_id'] |