Package tlslite :: Package utils :: Module python_rc4
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Source Code for Module tlslite.utils.python_rc4

 1  # Author: Trevor Perrin 
 2  # See the LICENSE file for legal information regarding use of this file. 
 3   
 4  """Pure-Python RC4 implementation.""" 
 5   
 6  from .rc4 import RC4 
 7  from .cryptomath import * 
 8   
9 -def new(key):
10 return Python_RC4(key)
11
12 -class Python_RC4(RC4):
13 - def __init__(self, keyBytes):
14 RC4.__init__(self, keyBytes, "python") 15 S = [i for i in range(256)] 16 j = 0 17 for i in range(256): 18 j = (j + S[i] + keyBytes[i % len(keyBytes)]) % 256 19 S[i], S[j] = S[j], S[i] 20 21 self.S = S 22 self.i = 0 23 self.j = 0
24
25 - def encrypt(self, plaintextBytes):
26 ciphertextBytes = plaintextBytes[:] 27 S = self.S 28 i = self.i 29 j = self.j 30 for x in range(len(ciphertextBytes)): 31 i = (i + 1) % 256 32 j = (j + S[i]) % 256 33 S[i], S[j] = S[j], S[i] 34 t = (S[i] + S[j]) % 256 35 ciphertextBytes[x] ^= S[t] 36 self.i = i 37 self.j = j 38 return ciphertextBytes
39
40 - def decrypt(self, ciphertext):
41 return self.encrypt(ciphertext)
42