migrate openstack hook to opnfv

Change-Id: I1e828dae38820fdff93966e57691b344af01140f
Signed-off-by: WuKong <rebirthmonkey@gmail.com>

1 files changed, 210 insertions, 0 deletions

diff --git a/keystonemiddleware-moon/keystonemiddleware/auth_token/_memcache_crypt.py b/keystonemiddleware-moon/keystonemiddleware/auth_token/_memcache_crypt.py
new file mode 100644
index 00000000..2e45571f
--- /dev/null
+++ b/keystonemiddleware-moon/keystonemiddleware/auth_token/_memcache_crypt.py
@@ -0,0 +1,210 @@
+# 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'])