diff options
Diffstat (limited to 'client/src/leap/soledad/client/_crypto.py')
| -rw-r--r-- | client/src/leap/soledad/client/_crypto.py | 41 |
1 files changed, 26 insertions, 15 deletions
diff --git a/client/src/leap/soledad/client/_crypto.py b/client/src/leap/soledad/client/_crypto.py index d9211322..4bbdd044 100644 --- a/client/src/leap/soledad/client/_crypto.py +++ b/client/src/leap/soledad/client/_crypto.py @@ -54,7 +54,7 @@ BLOB_SIGNATURE_MAGIC = '\x13\x37' ENC_SCHEME = namedtuple('SCHEME', 'symkey')(1) -ENC_METHOD = namedtuple('METHOD', 'aes_256_gcm')(1) +ENC_METHOD = namedtuple('METHOD', 'aes_256_ctr aes_256_gcm')(1, 2) DocInfo = namedtuple('DocInfo', 'doc_id rev') @@ -123,9 +123,9 @@ class SoledadCrypto(object): return decryptor.decrypt() -def encrypt_sym(data, key): +def encrypt_sym(data, key, method=ENC_METHOD.aes_256_gcm): """ - Encrypt data using AES-256 cipher in GCM mode. + Encrypt data using AES-256 cipher in selected mode. :param data: The data to be encrypted. :type data: str @@ -136,17 +136,18 @@ def encrypt_sym(data, key): encoded as base64. :rtype: (str, str) """ - encryptor = AESWriter(key) + mode = _mode_by_method(method) + encryptor = AESWriter(key, mode=mode) encryptor.write(data) _, ciphertext = encryptor.end() iv = base64.b64encode(encryptor.iv) - tag = base64.b64encode(encryptor.tag) - return iv, tag, ciphertext + tag = encryptor.tag or '' + return iv, ciphertext + tag -def decrypt_sym(data, key, iv, tag): +def decrypt_sym(data, key, iv, method=ENC_METHOD.aes_256_gcm): """ - Decrypt data using AES-256 cipher in GCM mode. + Decrypt data using AES-256 cipher in selected mode. :param data: The data to be decrypted. :type data: str @@ -160,8 +161,11 @@ def decrypt_sym(data, key, iv, tag): :rtype: str """ _iv = base64.b64decode(str(iv)) - tag = base64.b64decode(str(tag)) - decryptor = AESWriter(key, _iv, tag=tag) + 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 @@ -315,12 +319,12 @@ class AESWriter(object): """ implements(interfaces.IConsumer) - def __init__(self, key, iv=None, _buffer=None, tag=None): + def __init__(self, key, iv=None, _buffer=None, tag=None, mode=modes.GCM): if len(key) != 32: raise EncryptionDecryptionError('key is not 256 bits') self.iv = iv or os.urandom(16) self.buffer = _buffer or BytesIO() - cipher = _get_aes_gcm_cipher(key, self.iv, tag) + cipher = _get_aes_cipher(key, self.iv, tag, mode) cipher = cipher.decryptor() if tag else cipher.encryptor() self.cipher, self.aead = cipher, '' @@ -330,7 +334,7 @@ class AESWriter(object): @property def tag(self): - return self.cipher.tag + return getattr(self.cipher, 'tag', None) def write(self, data): self.buffer.write(self.cipher.update(data)) @@ -366,10 +370,17 @@ def _get_sym_key_for_doc(doc_id, secret): return _hmac_sha256(key, doc_id) -def _get_aes_gcm_cipher(key, iv, tag): - mode = modes.GCM(iv, tag) +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 _split(base64_raw_payload): return imap(base64.urlsafe_b64decode, re.split(' ', base64_raw_payload)) + + +def _mode_by_method(method): + if method == ENC_METHOD.aes_256_gcm: + return modes.GCM + else: + return modes.CTR |