Add google-endpoints to third_party/.

third_party/google-endpoints/Crypto/Cipher/ARC2.py

+# -*- coding: utf-8 -*-
+#
+#  Cipher/ARC2.py : ARC2.py
+#
+# ===================================================================
+# The contents of this file are dedicated to the public domain.  To
+# the extent that dedication to the public domain is not available,
+# everyone is granted a worldwide, perpetual, royalty-free,
+# non-exclusive license to exercise all rights associated with the
+# contents of this file for any purpose whatsoever.
+# No rights are reserved.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+# BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+# ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+# ===================================================================
+"""RC2 symmetric cipher
+
+RC2_ (Rivest's Cipher version 2)  is a symmetric block cipher designed
+by Ron Rivest in 1987. The cipher started as a proprietary design,
+that was reverse engineered and anonymously posted on Usenet in 1996.
+For this reason, the algorithm was first called *Alleged* RC2 (ARC2),
+since the company that owned RC2 (RSA Data Inc.) did not confirm whether
+the details leaked into public domain were really correct.
+
+The company eventually published its full specification in RFC2268_.
+
+RC2 has a fixed data block size of 8 bytes. Length of its keys can vary from
+8 to 128 bits. One particular property of RC2 is that the actual
+cryptographic strength of the key (*effective key length*) can be reduced 
+via a parameter.
+
+Even though RC2 is not cryptographically broken, it has not been analyzed as
+thoroughly as AES, which is also faster than RC2.
+
+New designs should not use RC2.
+
+As an example, encryption can be done as follows:
+
+    >>> from Crypto.Cipher import ARC2
+    >>> from Crypto import Random
+    >>>
+    >>> key = b'Sixteen byte key'
+    >>> iv = Random.new().read(ARC2.block_size)
+    >>> cipher = ARC2.new(key, ARC2.MODE_CFB, iv)
+    >>> msg = iv + cipher.encrypt(b'Attack at dawn')
+
+.. _RC2: http://en.wikipedia.org/wiki/RC2
+.. _RFC2268: http://tools.ietf.org/html/rfc2268
+
+:undocumented: __revision__, __package__
+"""
+
+__revision__ = "$Id$"
+
+from Crypto.Cipher import blockalgo
+from Crypto.Cipher import _ARC2
+
+class RC2Cipher (blockalgo.BlockAlgo):
+    """RC2 cipher object"""
+
+    def __init__(self, key, *args, **kwargs):
+        """Initialize an ARC2 cipher object
+        
+        See also `new()` at the module level."""
+        blockalgo.BlockAlgo.__init__(self, _ARC2, key, *args, **kwargs)
+
+def new(key, *args, **kwargs):
+    """Create a new RC2 cipher
+
+    :Parameters:
+      key : byte string
+        The secret key to use in the symmetric cipher.
+        Its length can vary from 1 to 128 bytes.
+    :Keywords:
+      mode : a *MODE_** constant
+        The chaining mode to use for encryption or decryption.
+        Default is `MODE_ECB`.
+      IV : byte string
+        The initialization vector to use for encryption or decryption.
+        
+        It is ignored for `MODE_ECB` and `MODE_CTR`.
+
+        For `MODE_OPENPGP`, IV must be `block_size` bytes long for encryption
+        and `block_size` +2 bytes for decryption (in the latter case, it is
+        actually the *encrypted* IV which was prefixed to the ciphertext).
+        It is mandatory.
+       
+        For all other modes, it must be `block_size` bytes longs. It is optional and
+        when not present it will be given a default value of all zeroes.
+      counter : callable
+        (*Only* `MODE_CTR`). A stateful function that returns the next
+        *counter block*, which is a byte string of `block_size` bytes.
+        For better performance, use `Crypto.Util.Counter`.
+      segment_size : integer
+        (*Only* `MODE_CFB`).The number of bits the plaintext and ciphertext
+        are segmented in.
+        It must be a multiple of 8. If 0 or not specified, it will be assumed to be 8.
+      effective_keylen : integer
+        Maximum cryptographic strength of the key, in bits.
+        It can vary from 0 to 1024. The default value is 1024.
+
+    :Return: an `RC2Cipher` object
+    """
+    return RC2Cipher(key, *args, **kwargs)
+
+#: Electronic Code Book (ECB). See `blockalgo.MODE_ECB`.
+MODE_ECB = 1
+#: Cipher-Block Chaining (CBC). See `blockalgo.MODE_CBC`.
+MODE_CBC = 2
+#: Cipher FeedBack (CFB). See `blockalgo.MODE_CFB`.
+MODE_CFB = 3
+#: This mode should not be used.
+MODE_PGP = 4
+#: Output FeedBack (OFB). See `blockalgo.MODE_OFB`.
+MODE_OFB = 5
+#: CounTer Mode (CTR). See `blockalgo.MODE_CTR`.
+MODE_CTR = 6
+#: OpenPGP Mode. See `blockalgo.MODE_OPENPGP`.
+MODE_OPENPGP = 7
+#: Size of a data block (in bytes)
+block_size = 8
+#: Size of a key (in bytes)
+key_size = xrange(1,16+1)
+