src/Cipher/RC5.py

   1 from blockcipher import *
   2 try:
   3     import Crypto.Cipher.RC5
   4 except ImportError:
   5     print "Crypto.Cipher.RC5 isn't available. You're probably using the Debian pycrypto version. Install the original pycrypto for RC5."
   6     raise
   7
   8 def new(key,mode=MODE_ECB,IV=None,counter=None,rounds=12,word_size=32):
   9     """Create a new cipher object
  10
  11     RC5 using pycrypto for algo and pycryptoplus for ciphermode
  12
  13     new(key,mode=MODE_ECB,IV=None,counter=None):
  14         key = raw string containing the keys
  15         mode = python_AES.MODE_ECB/CBC/CFB/OFB/CTR/CMAC, default is ECB
  16         IV = IV as a raw string
  17             -> only needed for CBC mode
  18         counter = counter object (CryptoPlus.Util.util.Counter)
  19             -> only needed for CTR mode
  20
  21     https://www.cosic.esat.kuleuven.be/nessie/testvectors/
  22     -----------------------------------------
  23     >>> from CryptoPlus.Cipher import RC5
  24     >>> key = "00000000000000000000000000000000".decode('hex')
  25     >>> plaintext = "0000000000000000".decode('hex')
  26     >>> rounds = 12
  27     >>> cipher = RC5.new(key,RC5.MODE_ECB,rounds=rounds)
  28     >>> cipher.encrypt(plaintext).encode('hex')
  29     '21a5dbee154b8f6d'
  30     """
  31     return RC5(key,mode,IV,counter,rounds,word_size)
  32
  33 class RC5(BlockCipher):
  34     def __init__(self,key,mode,IV,counter,rounds,word_size):
  35         if mode == MODE_XTS:
  36             #XTS implementation only works with blocksizes of 16 bytes
  37             assert type(key) is tuple
  38             self.cipher = Crypto.Cipher.RC5.new(key[0],rounds=rounds,word_size=word_size)
  39             self.cipher2 = Crypto.Cipher.RC5.new(key[1],rounds=rounds,word_size=word_size)
  40             assert self.cipher.block_size == 16
  41         elif mode == MODE_CMAC:
  42             #CMAC implementation only supports blocksizes of 8 and 16 bytes
  43             self.cipher = Crypto.Cipher.RC5.new(key,rounds=rounds,word_size=word_size)
  44             assert self.cipher.block_size in (8,16)
  45         else:
  46             self.cipher = Crypto.Cipher.RC5.new(key,rounds=rounds,word_size=word_size)
  47         self.blocksize = self.cipher.block_size
  48         BlockCipher.__init__(self,key,mode,IV,counter)
  49
  50 def _test():
  51     import doctest
  52     doctest.testmod()
  53
  54 if __name__ == "__main__":
  55     _test()