# Author: Trevor Perrin
# See the LICENSE file for legal information regarding use of this file.
"""Pure-Python RC4 implementation."""
from .rc4 import RC4
from .cryptomath import *
[docs]
def new(key):
return Python_RC4(key)
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class Python_RC4(RC4):
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def __init__(self, keyBytes):
RC4.__init__(self, keyBytes, "python")
S = [i for i in range(256)]
j = 0
for i in range(256):
j = (j + S[i] + keyBytes[i % len(keyBytes)]) % 256
S[i], S[j] = S[j], S[i]
self.S = S
self.i = 0
self.j = 0
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def encrypt(self, plaintextBytes):
ciphertextBytes = plaintextBytes[:]
S = self.S
i = self.i
j = self.j
for x in range(len(ciphertextBytes)):
i = (i + 1) % 256
j = (j + S[i]) % 256
S[i], S[j] = S[j], S[i]
t = (S[i] + S[j]) % 256
ciphertextBytes[x] ^= S[t]
self.i = i
self.j = j
return ciphertextBytes
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def decrypt(self, ciphertext):
return self.encrypt(ciphertext)