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Diffstat (limited to 'keystonemiddleware-moon/keystonemiddleware/auth_token/_memcache_crypt.py')
| -rw-r--r-- | keystonemiddleware-moon/keystonemiddleware/auth_token/_memcache_crypt.py | 210 |
1 files changed, 0 insertions, 210 deletions
diff --git a/keystonemiddleware-moon/keystonemiddleware/auth_token/_memcache_crypt.py b/keystonemiddleware-moon/keystonemiddleware/auth_token/_memcache_crypt.py deleted file mode 100644 index 2e45571f..00000000 --- a/keystonemiddleware-moon/keystonemiddleware/auth_token/_memcache_crypt.py +++ /dev/null @@ -1,210 +0,0 @@ -# Copyright 2010-2013 OpenStack Foundation -# -# Licensed under the Apache License, Version 2.0 (the "License"); -# you may not use this file except in compliance with the License. -# You may obtain a copy of the License at -# -# http://www.apache.org/licenses/LICENSE-2.0 -# -# Unless required by applicable law or agreed to in writing, software -# distributed under the License is distributed on an "AS IS" BASIS, -# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or -# implied. -# See the License for the specific language governing permissions and -# limitations under the License. - -""" -Utilities for memcache encryption and integrity check. - -Data should be serialized before entering these functions. Encryption -has a dependency on the pycrypto. If pycrypto is not available, -CryptoUnavailableError will be raised. - -This module will not be called unless signing or encryption is enabled -in the config. It will always validate signatures, and will decrypt -data if encryption is enabled. It is not valid to mix protection -modes. - -""" - -import base64 -import functools -import hashlib -import hmac -import math -import os -import six -import sys - -from keystonemiddleware.i18n import _ - -# make sure pycrypto is available -try: - from Crypto.Cipher import AES -except ImportError: - AES = None - -HASH_FUNCTION = hashlib.sha384 -DIGEST_LENGTH = HASH_FUNCTION().digest_size -DIGEST_SPLIT = DIGEST_LENGTH // 3 -DIGEST_LENGTH_B64 = 4 * int(math.ceil(DIGEST_LENGTH / 3.0)) - - -class InvalidMacError(Exception): - """raise when unable to verify MACed data. - - This usually indicates that data had been expectedly modified in memcache. - - """ - pass - - -class DecryptError(Exception): - """raise when unable to decrypt encrypted data. - - """ - pass - - -class CryptoUnavailableError(Exception): - """raise when Python Crypto module is not available. - - """ - pass - - -def assert_crypto_availability(f): - """Ensure Crypto module is available.""" - - @functools.wraps(f) - def wrapper(*args, **kwds): - if AES is None: - raise CryptoUnavailableError() - return f(*args, **kwds) - return wrapper - - -if sys.version_info >= (3, 3): - constant_time_compare = hmac.compare_digest -else: - def constant_time_compare(first, second): - """Returns True if both string inputs are equal, otherwise False. - - This function should take a constant amount of time regardless of - how many characters in the strings match. - - """ - if len(first) != len(second): - return False - result = 0 - if six.PY3 and isinstance(first, bytes) and isinstance(second, bytes): - for x, y in zip(first, second): - result |= x ^ y - else: - for x, y in zip(first, second): - result |= ord(x) ^ ord(y) - return result == 0 - - -def derive_keys(token, secret, strategy): - """Derives keys for MAC and ENCRYPTION from the user-provided - secret. The resulting keys should be passed to the protect and - unprotect functions. - - As suggested by NIST Special Publication 800-108, this uses the - first 128 bits from the sha384 KDF for the obscured cache key - value, the second 128 bits for the message authentication key and - the remaining 128 bits for the encryption key. - - This approach is faster than computing a separate hmac as the KDF - for each desired key. - """ - digest = hmac.new(secret, token + strategy, HASH_FUNCTION).digest() - return {'CACHE_KEY': digest[:DIGEST_SPLIT], - 'MAC': digest[DIGEST_SPLIT: 2 * DIGEST_SPLIT], - 'ENCRYPTION': digest[2 * DIGEST_SPLIT:], - 'strategy': strategy} - - -def sign_data(key, data): - """Sign the data using the defined function and the derived key.""" - mac = hmac.new(key, data, HASH_FUNCTION).digest() - return base64.b64encode(mac) - - -@assert_crypto_availability -def encrypt_data(key, data): - """Encrypt the data with the given secret key. - - Padding is n bytes of the value n, where 1 <= n <= blocksize. - """ - iv = os.urandom(16) - cipher = AES.new(key, AES.MODE_CBC, iv) - padding = 16 - len(data) % 16 - return iv + cipher.encrypt(data + six.int2byte(padding) * padding) - - -@assert_crypto_availability -def decrypt_data(key, data): - """Decrypt the data with the given secret key.""" - iv = data[:16] - cipher = AES.new(key, AES.MODE_CBC, iv) - try: - result = cipher.decrypt(data[16:]) - except Exception: - raise DecryptError(_('Encrypted data appears to be corrupted.')) - - # Strip the last n padding bytes where n is the last value in - # the plaintext - return result[:-1 * six.byte2int([result[-1]])] - - -def protect_data(keys, data): - """Given keys and serialized data, returns an appropriately - protected string suitable for storage in the cache. - - """ - if keys['strategy'] == b'ENCRYPT': - data = encrypt_data(keys['ENCRYPTION'], data) - - encoded_data = base64.b64encode(data) - - signature = sign_data(keys['MAC'], encoded_data) - return signature + encoded_data - - -def unprotect_data(keys, signed_data): - """Given keys and cached string data, verifies the signature, - decrypts if necessary, and returns the original serialized data. - - """ - # cache backends return None when no data is found. We don't mind - # that this particular special value is unsigned. - if signed_data is None: - return None - - # First we calculate the signature - provided_mac = signed_data[:DIGEST_LENGTH_B64] - calculated_mac = sign_data( - keys['MAC'], - signed_data[DIGEST_LENGTH_B64:]) - - # Then verify that it matches the provided value - if not constant_time_compare(provided_mac, calculated_mac): - raise InvalidMacError(_('Invalid MAC; data appears to be corrupted.')) - - data = base64.b64decode(signed_data[DIGEST_LENGTH_B64:]) - - # then if necessary decrypt the data - if keys['strategy'] == b'ENCRYPT': - data = decrypt_data(keys['ENCRYPTION'], data) - - return data - - -def get_cache_key(keys): - """Given keys generated by derive_keys(), returns a base64 - encoded value suitable for use as a cache key in memcached. - - """ - return base64.b64encode(keys['CACHE_KEY']) |