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#!/usr/bin/env python2
""" Python implementation of Arcfour encryption algorithm.
This code is in the public domain.
"""
## Arcfour
##
class Arcfour(object):
"""
>>> Arcfour('Key').process('Plaintext').encode('hex')
'bbf316e8d940af0ad3'
>>> Arcfour('Wiki').process('pedia').encode('hex')
'1021bf0420'
>>> Arcfour('Secret').process('Attack at dawn').encode('hex')
'45a01f645fc35b383552544b9bf5'
"""
def __init__(self, key):
s = range(256)
j = 0
klen = len(key)
for i in xrange(256):
j = (j + s[i] + ord(key[i % klen])) % 256
(s[i], s[j]) = (s[j], s[i])
self.s = s
(self.i, self.j) = (0, 0)
return
def process(self, data):
(i, j) = (self.i, self.j)
s = self.s
r = ''
for c in data:
i = (i+1) % 256
j = (j+s[i]) % 256
(s[i], s[j]) = (s[j], s[i])
k = s[(s[i]+s[j]) % 256]
r += chr(ord(c) ^ k)
(self.i, self.j) = (i, j)
return r
# test
if __name__ == '__main__':
import doctest
doctest.testmod()
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