/gdata/tlslite/utils/Python_RC4.py
http://radioappz.googlecode.com/ · Python · 39 lines · 32 code · 6 blank · 1 comment · 3 complexity · 6131ab9c69edb2989f80cd67b95847ca MD5 · raw file
- """Pure-Python RC4 implementation."""
- from RC4 import RC4
- from cryptomath import *
- def new(key):
- return Python_RC4(key)
- class Python_RC4(RC4):
- def __init__(self, key):
- RC4.__init__(self, key, "python")
- keyBytes = stringToBytes(key)
- 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
- def encrypt(self, plaintext):
- plaintextBytes = stringToBytes(plaintext)
- S = self.S
- i = self.i
- j = self.j
- for x in range(len(plaintextBytes)):
- i = (i + 1) % 256
- j = (j + S[i]) % 256
- S[i], S[j] = S[j], S[i]
- t = (S[i] + S[j]) % 256
- plaintextBytes[x] ^= S[t]
- self.i = i
- self.j = j
- return bytesToString(plaintextBytes)
- def decrypt(self, ciphertext):
- return self.encrypt(ciphertext)