diff options
Diffstat (limited to 'client/src/leap/soledad/client/crypto.py')
| -rw-r--r-- | client/src/leap/soledad/client/crypto.py | 212 |
1 files changed, 118 insertions, 94 deletions
diff --git a/client/src/leap/soledad/client/crypto.py b/client/src/leap/soledad/client/crypto.py index d81c883b..da067237 100644 --- a/client/src/leap/soledad/client/crypto.py +++ b/client/src/leap/soledad/client/crypto.py @@ -42,6 +42,9 @@ MAC_KEY_LENGTH = 64 crypto_backend = MultiBackend([OpenSSLBackend()]) +# TODO -- deprecate. +# Secrets still using this. + def encrypt_sym(data, key): """ Encrypt data using AES-256 cipher in CTR mode. @@ -68,7 +71,10 @@ def encrypt_sym(data, key): return binascii.b2a_base64(iv), ciphertext -def decrypt_sym(data, key, iv): +# FIXME decryption of the secrets doc is still using b64 +# Deprecate that, move to hex. + +def decrypt_sym(data, key, iv, encoding='base64'): """ Decrypt some data previously encrypted using AES-256 cipher in CTR mode. @@ -78,7 +84,7 @@ def decrypt_sym(data, key, iv): long). :type key: str :param iv: The initialization vector. - :type iv: long + :type iv: str (it's b64 encoded by secrets, hex by deserializing from wire) :return: The decrypted data. :rtype: str @@ -88,7 +94,12 @@ def decrypt_sym(data, key, iv): soledad_assert( len(key) == 32, # 32 x 8 = 256 bits. 'Wrong key size: %s (must be 256 bits long).' % len(key)) - iv = binascii.a2b_base64(iv) + + if encoding == 'base64': + iv = binascii.a2b_base64(iv) + elif encoding == 'hex': + iv = binascii.a2b_hex(iv) + cipher = Cipher(algorithms.AES(key), modes.CTR(iv), backend=crypto_backend) decryptor = cipher.decryptor() return decryptor.update(data) + decryptor.finalize() @@ -159,17 +170,17 @@ class SoledadCrypto(object): doc_id, hashlib.sha256).digest() - def encrypt_doc(self, doc): - """ - Wrapper around encrypt_docstr that accepts the document as argument. - - :param doc: the document. - :type doc: SoledadDocument - """ - key = self.doc_passphrase(doc.doc_id) - - return encrypt_docstr( - doc.get_json(), doc.doc_id, doc.rev, key, self._secret) + #def encrypt_doc(self, doc): + #""" + #Wrapper around encrypt_docstr that accepts the document as argument. +# + #:param doc: the document. + #:type doc: SoledadDocument + #""" + #key = self.doc_passphrase(doc.doc_id) +# + #return encrypt_docstr( + #doc.get_json(), doc.doc_id, doc.rev, key, self._secret) def decrypt_doc(self, doc): """ @@ -194,6 +205,8 @@ class SoledadCrypto(object): # Crypto utilities for a SoledadDocument. # +# TODO should be ported to streaming consumer + def mac_doc(doc_id, doc_rev, ciphertext, enc_scheme, enc_method, enc_iv, mac_method, secret): """ @@ -212,7 +225,7 @@ def mac_doc(doc_id, doc_rev, ciphertext, enc_scheme, enc_method, enc_iv, :param ciphertext: The content of the document. :type ciphertext: str :param enc_scheme: The encryption scheme. - :type enc_scheme: str + :type enc_scheme: bytes :param enc_method: The encryption method. :type enc_method: str :param enc_iv: The encryption initialization vector. @@ -231,6 +244,7 @@ def mac_doc(doc_id, doc_rev, ciphertext, enc_scheme, enc_method, enc_iv, soledad_assert(mac_method == crypto.MacMethods.HMAC) except AssertionError: raise crypto.UnknownMacMethodError + template = "{doc_id}{doc_rev}{ciphertext}{enc_scheme}{enc_method}{enc_iv}" content = template.format( doc_id=doc_id, @@ -239,78 +253,82 @@ def mac_doc(doc_id, doc_rev, ciphertext, enc_scheme, enc_method, enc_iv, enc_scheme=enc_scheme, enc_method=enc_method, enc_iv=enc_iv) - return hmac.new( + + digest = hmac.new( doc_mac_key(doc_id, secret), content, hashlib.sha256).digest() + return digest -def encrypt_docstr(docstr, doc_id, doc_rev, key, secret): - """ - Encrypt C{doc}'s content. - - Encrypt doc's contents using AES-256 CTR mode and return a valid JSON - string representing the following: - - { - crypto.ENC_JSON_KEY: '<encrypted doc JSON string>', - crypto.ENC_SCHEME_KEY: 'symkey', - crypto.ENC_METHOD_KEY: crypto.EncryptionMethods.AES_256_CTR, - crypto.ENC_IV_KEY: '<the initial value used to encrypt>', - MAC_KEY: '<mac>' - crypto.MAC_METHOD_KEY: 'hmac' - } - - :param docstr: A representation of the document to be encrypted. - :type docstr: str or unicode. - - :param doc_id: The document id. - :type doc_id: str - - :param doc_rev: The document revision. - :type doc_rev: str - - :param key: The key used to encrypt ``data`` (must be 256 bits long). - :type key: str - - :param secret: The Soledad storage secret (used for MAC auth). - :type secret: str - - :return: The JSON serialization of the dict representing the encrypted - content. - :rtype: str - """ - enc_scheme = crypto.EncryptionSchemes.SYMKEY - enc_method = crypto.EncryptionMethods.AES_256_CTR - mac_method = crypto.MacMethods.HMAC - enc_iv, ciphertext = encrypt_sym( - str(docstr), # encryption/decryption routines expect str - key) - mac = binascii.b2a_hex( # store the mac as hex. - mac_doc( - doc_id, - doc_rev, - ciphertext, - enc_scheme, - enc_method, - enc_iv, - mac_method, - secret)) +#def encrypt_docstr(docstr, doc_id, doc_rev, key, secret): + #""" + #Encrypt C{doc}'s content. +# + #Encrypt doc's contents using AES-256 CTR mode and return a valid JSON + #string representing the following: +# + #{ + #crypto.ENC_JSON_KEY: '<encrypted doc JSON string>', + #crypto.ENC_SCHEME_KEY: 'symkey', + #crypto.ENC_METHOD_KEY: crypto.EncryptionMethods.AES_256_CTR, + #crypto.ENC_IV_KEY: '<the initial value used to encrypt>', + #MAC_KEY: '<mac>' + #crypto.MAC_METHOD_KEY: 'hmac' + #} +# + #:param docstr: A representation of the document to be encrypted. + #:type docstr: str or unicode. +# + #:param doc_id: The document id. + #:type doc_id: str +# + #:param doc_rev: The document revision. + #:type doc_rev: str +# + #:param key: The key used to encrypt ``data`` (must be 256 bits long). + #:type key: str +# + #:param secret: The Soledad storage secret (used for MAC auth). + #:type secret: str +# + #:return: The JSON serialization of the dict representing the encrypted + #content. + #:rtype: str + #""" + #enc_scheme = crypto.EncryptionSchemes.SYMKEY + #enc_method = crypto.EncryptionMethods.AES_256_CTR + #mac_method = crypto.MacMethods.HMAC + #enc_iv, ciphertext = encrypt_sym( + #str(docstr), # encryption/decryption routines expect str + #key) + #mac = binascii.b2a_hex( # store the mac as hex. + #mac_doc( + #doc_id, + #doc_rev, + #ciphertext, + #enc_scheme, + #enc_method, + #enc_iv, + #mac_method, + #secret)) # 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) - logger.debug("encrypting doc: %s" % doc_id) - return json.dumps({ - crypto.ENC_JSON_KEY: hex_ciphertext, - crypto.ENC_SCHEME_KEY: enc_scheme, - crypto.ENC_METHOD_KEY: enc_method, - crypto.ENC_IV_KEY: enc_iv, - crypto.MAC_KEY: mac, - crypto.MAC_METHOD_KEY: mac_method, - }) + #hex_ciphertext = binascii.b2a_hex(ciphertext) + #log.debug("Encrypting doc: %s" % doc_id) + #return json.dumps({ + #crypto.ENC_JSON_KEY: hex_ciphertext, + #crypto.ENC_SCHEME_KEY: enc_scheme, + #crypto.ENC_METHOD_KEY: enc_method, + #crypto.ENC_IV_KEY: enc_iv, + #crypto.MAC_KEY: mac, + #crypto.MAC_METHOD_KEY: mac_method, + #}) +# +# TODO port to _crypto def _verify_doc_mac(doc_id, doc_rev, ciphertext, enc_scheme, enc_method, enc_iv, mac_method, secret, doc_mac): """ @@ -338,6 +356,7 @@ def _verify_doc_mac(doc_id, doc_rev, ciphertext, enc_scheme, enc_method, :raise crypto.UnknownMacMethodError: Raised when C{mac_method} is unknown. :raise crypto.WrongMacError: Raised when MAC could not be verified. """ + # TODO mac_doc should be ported to Streaming also calculated_mac = mac_doc( doc_id, doc_rev, @@ -347,16 +366,15 @@ def _verify_doc_mac(doc_id, doc_rev, ciphertext, enc_scheme, enc_method, enc_iv, mac_method, secret) - # we compare mac's hashes to avoid possible timing attacks that might - # exploit python's builtin comparison operator behaviour, which fails - # immediatelly when non-matching bytes are found. - doc_mac_hash = hashlib.sha256( - binascii.a2b_hex( # the mac is stored as hex - doc_mac)).digest() - calculated_mac_hash = hashlib.sha256(calculated_mac).digest() - - if doc_mac_hash != calculated_mac_hash: - logger.warn("wrong MAC while decrypting doc...") + + ok = hmac.compare_digest( + str(calculated_mac), + binascii.a2b_hex(doc_mac)) + + if not ok: + loggger.warn("wrong MAC while decrypting doc...") + loggger.info(u'given: %s' % doc_mac) + loggger.info(u'calculated: %s' % binascii.b2a_hex(calculated_mac)) raise crypto.WrongMacError("Could not authenticate document's " "contents.") @@ -415,12 +433,17 @@ def decrypt_doc_dict(doc_dict, doc_id, doc_rev, key, secret): ]) soledad_assert(expected_keys.issubset(set(doc_dict.keys()))) - ciphertext = binascii.a2b_hex(doc_dict[crypto.ENC_JSON_KEY]) - enc_scheme = doc_dict[crypto.ENC_SCHEME_KEY] - enc_method = doc_dict[crypto.ENC_METHOD_KEY] - enc_iv = doc_dict[crypto.ENC_IV_KEY] - doc_mac = doc_dict[crypto.MAC_KEY] - mac_method = doc_dict[crypto.MAC_METHOD_KEY] + d = doc_dict + decode = binascii.a2b_hex + + enc_scheme = d[crypto.ENC_SCHEME_KEY] + enc_method = d[crypto.ENC_METHOD_KEY] + doc_mac = d[crypto.MAC_KEY] + mac_method = d[crypto.MAC_METHOD_KEY] + enc_iv = d[crypto.ENC_IV_KEY] + + ciphertext_hex = d[crypto.ENC_JSON_KEY] + ciphertext = decode(ciphertext_hex) soledad_assert(enc_scheme == crypto.EncryptionSchemes.SYMKEY) @@ -428,7 +451,8 @@ def decrypt_doc_dict(doc_dict, doc_id, doc_rev, key, secret): doc_id, doc_rev, ciphertext, enc_scheme, enc_method, enc_iv, mac_method, secret, doc_mac) - return decrypt_sym(ciphertext, key, enc_iv) + decr = decrypt_sym(ciphertext, key, enc_iv, encoding='hex') + return decr def is_symmetrically_encrypted(doc): |