ó Bd\Rc@s‘dZdZddlmZddlmZdejfd„ƒYZd„ZdZd Z d Z d Z d Z d Z dZdZeddƒZdS(sERC2 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__ s$Id$iÿÿÿÿ(t blockalgo(t_ARC2t RC2CiphercBseZdZd„ZRS(sRC2 cipher objectcOs tjj|t|||ŽdS(sWInitialize an ARC2 cipher object See also `new()` at the module level.N(Rt BlockAlgot__init__R(tselftkeytargstkwargs((s8/usr/lib64/python2.7/site-packages/Crypto/Cipher/ARC2.pyRCs(t__name__t __module__t__doc__R(((s8/usr/lib64/python2.7/site-packages/Crypto/Cipher/ARC2.pyR@scOst|||ŽS(sùCreate 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 (R(RRR((s8/usr/lib64/python2.7/site-packages/Crypto/Cipher/ARC2.pytnewIs%iiiiiiiiiNi(R t __revision__t Crypto.CipherRRRRR tMODE_ECBtMODE_CBCtMODE_CFBtMODE_PGPtMODE_OFBtMODE_CTRt MODE_OPENPGPt block_sizetxrangetkey_size(((s8/usr/lib64/python2.7/site-packages/Crypto/Cipher/ARC2.pyt9s (