src/Cipher/python_Twofish.py

   1 from blockcipher import *
   2 from pytwofish import Twofish
   3
   4 def new(key,mode=MODE_ECB,IV=None,counter=None):
   5     """Create a new cipher object
   6
   7     Wrapper for pure python implementation pytwofish.py
   8
   9     new(key,mode=MODE_ECB,IV=None,counter=None):
  10         key = raw string containing the key
  11         mode = python_Twofish.MODE_ECB/CBC/CFB/OFB/CTR/XTS/CMAC, default is ECB
  12             -> for every mode, except ECB and CTR, it is important to construct a seperate cipher for encryption and decryption
  13         IV = IV as a raw string
  14             -> needed for CBC, CFB and OFB mode
  15         counter = counter object (CryptoPlus.Util.util.Counter)
  16             -> only needed for CTR mode
  17             -> use a seperate counter object for the cipher and decipher: the counter is updated directly, not a copy
  18                 see CTR example further on in the docstring
  19
  20     EXAMPLE:
  21     ----------
  22     http://www.schneier.com/code/ecb_ival.txt -> test vector I=5
  23
  24     >>> import python_Twofish
  25     >>> from binascii import hexlify, unhexlify
  26     >>> cipher = python_Twofish.new(unhexlify('019F9809DE1711858FAAC3A3BA20FBC3'))
  27     >>> hexlify(cipher.encrypt(unhexlify('6363977DE839486297E661C6C9D668EB'))).upper()
  28     '816D5BD0FAE35342BF2A7412C246F752'
  29     >>> hexlify( cipher.decrypt(unhexlify(_)) ).upper()
  30     '6363977DE839486297E661C6C9D668EB'
  31     """
  32     return python_Twofish(key,mode,IV,counter)
  33
  34 class python_Twofish(BlockCipher):
  35     def __init__(self,key,mode,IV,counter):
  36         if mode == MODE_XTS:
  37             assert type(key) is tuple
  38             self.cipher = Twofish(key[1])
  39             self.cipher2 = Twofish(key[2])
  40         else:
  41             self.cipher = Twofish(key)
  42         self.blocksize = self.cipher.get_block_size()
  43         BlockCipher.__init__(self,key,mode,IV,counter)
  44
  45 def _test():
  46     import doctest
  47     doctest.testmod()
  48
  49 if __name__ == "__main__":
  50     _test()