diff options
Diffstat (limited to 'client/src/leap/soledad/client/_crypto.py')
| -rw-r--r-- | client/src/leap/soledad/client/_crypto.py | 60 |
1 files changed, 33 insertions, 27 deletions
diff --git a/client/src/leap/soledad/client/_crypto.py b/client/src/leap/soledad/client/_crypto.py index 109cf299..a235e246 100644 --- a/client/src/leap/soledad/client/_crypto.py +++ b/client/src/leap/soledad/client/_crypto.py @@ -24,10 +24,12 @@ import base64 import hashlib import hmac import os +import re import struct import time from io import BytesIO +from itertools import imap from collections import namedtuple import six @@ -54,6 +56,8 @@ MAC_KEY_LENGTH = 64 crypto_backend = MultiBackend([OpenSSLBackend()]) +PACMAN = struct.Struct('cQbb16s255p255p') + class ENC_SCHEME: symkey = 1 @@ -247,15 +251,14 @@ class BlobEncryptor(object): current_time = int(time.time()) - write(b'\x80') - write(struct.pack( - 'Qbb', + write(PACMAN.pack( + '\x80', current_time, ENC_SCHEME.symkey, - ENC_METHOD.aes_256_ctr)) - write(self.iv) - write(str(self.doc_id)) - write(str(self.rev)) + ENC_METHOD.aes_256_ctr, + self.iv, + str(self.doc_id), + str(self.rev))) def _end_crypto_stream(self, ignored): self._aes.end() @@ -267,7 +270,10 @@ class BlobEncryptor(object): hmac = self._hmac.result.getvalue() self.result.write( - base64.urlsafe_b64encode(preamble + encrypted + hmac)) + base64.urlsafe_b64encode(preamble)) + self.result.write(' ') + self.result.write( + base64.urlsafe_b64encode(encrypted + hmac)) self._preamble.close() self._aes_fd.close() self._hmac.result.close() @@ -297,17 +303,21 @@ class BlobDecryptor(object): def decrypt(self): try: - data = base64.urlsafe_b64decode(self.ciphertext.getvalue()) + preamble, ciphertext = _split(self.ciphertext.getvalue()) + hmac, ciphertext = ciphertext[-64:], ciphertext[:-64] except (TypeError, binascii.Error): raise InvalidBlob self.ciphertext.close() - - if not data or six.indexbytes(data, 0) != 0x80: + if len(preamble) != PACMAN.size: raise InvalidBlob + try: - ts, sch, meth = struct.unpack("Qbb", data[1:11]) + unpacked_data = PACMAN.unpack(preamble) + pad, ts, sch, meth, iv, doc_id, rev = unpacked_data except struct.error: raise InvalidBlob + if pad != '\x80': + raise InvalidBlob # TODO check timestamp if sch != ENC_SCHEME.symkey: @@ -316,21 +326,12 @@ class BlobDecryptor(object): 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 - 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]) + h.update(preamble) + h.update(ciphertext) try: h.verify(hmac) except InvalidSignature: @@ -457,12 +458,13 @@ def is_symmetrically_encrypted(doc): if not payload or 'raw' not in payload: return False payload = str(payload['raw']) - if len(payload) < 16: + if len(payload) < PACMAN.size: return False - header = base64.urlsafe_b64decode(payload[:18] + '==') - if six.indexbytes(header, 0) != 0x80: + payload = _split(payload).next() + if six.indexbytes(payload, 0) != 0x80: return False - ts, sch, meth = struct.unpack('Qbb', header[1:11]) + unpacked = PACMAN.unpack(payload) + ts, sch, meth = unpacked[1:4] return sch == ENC_SCHEME.symkey and meth == ENC_METHOD.aes_256_ctr @@ -485,3 +487,7 @@ def _get_sym_key_for_doc(doc_id, secret): def _get_aes_ctr_cipher(key, iv): return Cipher(algorithms.AES(key), modes.CTR(iv), backend=crypto_backend) + + +def _split(base64_raw_payload): + return imap(base64.urlsafe_b64decode, re.split(' ', base64_raw_payload)) |