diff options
Diffstat (limited to 'client/src/leap/soledad/client/_crypto.py')
| -rw-r--r-- | client/src/leap/soledad/client/_crypto.py | 83 |
1 files changed, 59 insertions, 24 deletions
diff --git a/client/src/leap/soledad/client/_crypto.py b/client/src/leap/soledad/client/_crypto.py index e4093a9e..ed861fdd 100644 --- a/client/src/leap/soledad/client/_crypto.py +++ b/client/src/leap/soledad/client/_crypto.py @@ -1,14 +1,37 @@ +# -*- 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 +""" + import binascii +import base64 import hashlib import hmac import os from cStringIO import StringIO -from twisted.persisted import dirdbm from twisted.internet import defer from twisted.internet import interfaces from twisted.internet import reactor +from twisted.logger import Logger +from twisted.persisted import dirdbm from twisted.web import client from twisted.web.client import FileBodyProducer @@ -23,11 +46,17 @@ from leap.common.config import get_path_prefix from leap.soledad.client.secrets import SoledadSecrets +log = Logger() + MAC_KEY_LENGTH = 64 crypto_backend = MultiBackend([OpenSSLBackend()]) +class EncryptionError(Exception): + pass + + class AESWriter(object): implements(interfaces.IConsumer) @@ -35,6 +64,10 @@ class AESWriter(object): def __init__(self, key, fd, iv=None): if iv is None: iv = os.urandom(16) + if len(key) != 32: + raise EncryptionError('key is not 256 bits') + if len(iv) != 16: + raise EncryptionError('iv is not 128 bits') cipher = _get_aes_ctr_cipher(key, iv) self.encryptor = cipher.encryptor() @@ -51,7 +84,6 @@ class AESWriter(object): def end(self): if not self.done: self.encryptor.finalize() - self.fd.seek(0) self.deferred.callback(self.fd) self.done = True @@ -91,18 +123,12 @@ class EncryptAndHMAC(object): -class NewDocCryptoStreamer(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": "ENC", - "_enc_iv": "IV", - "_mac": "MAC"}""" + 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): @@ -140,14 +166,12 @@ class NewDocCryptoStreamer(object): self.hmac_consumer.end() return defer.succeed('ok') - def persist_encrypted_doc(self, ignored, encoding='hex'): - # 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. - # this will benefit + # TODO make this pluggable: + # pass another class (CryptoSerializer) to which we pass + # the doc info, the encrypted_fd and the mac_digest - # TODO -- transition to hex: needs migration FIXME + 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': @@ -155,14 +179,25 @@ class NewDocCryptoStreamer(object): 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( - 'ENC', encode(self._encrypted_fd.read())).replace( - 'IV', binascii.b2a_base64(self.iv)).replace( - 'MAC', encode(self.hmac_consumer.digest)) + '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() @@ -174,14 +209,14 @@ class NewDocCryptoStreamer(object): self.hmac_consumer.write(pre) def _post_hmac(self): - # FIXME -- original impl passed b64 encoded iv post = '{enc_scheme}{enc_method}{enc_iv}'.format( enc_scheme='symkey', enc_method='aes-256-ctr', - enc_iv=binascii.b2a_base64(self.iv)) + enc_iv=binascii.b2a_hex(self.iv)) self.hmac_consumer.write(post) + def _hmac_sha256(key, data): return hmac.new(key, data, hashlib.sha256).digest() |