1# Impacket - Collection of Python classes for working with network protocols. 

2# 

3# SECUREAUTH LABS. Copyright (C) 2018 SecureAuth Corporation. All rights reserved. 

4# 

5# This software is provided under a slightly modified version 

6# of the Apache Software License. See the accompanying LICENSE file 

7# for more information. 

8# 

9# Description: 

10# IEEE 802.11 Network packet codecs. 

11# 

12# Author: 

13# Gustavo Moreira 

14# 

15 

16class RC4(): 

17 def __init__(self, key): 

18 bkey = bytearray(key) 

19 j = 0 

20 self.state = bytearray(range(256)) 

21 for i in range(256): 

22 j = (j + self.state[i] + bkey[i % len(key)]) & 0xff 

23 self.state[i],self.state[j] = self.state[j],self.state[i] # SSWAP(i,j) 

24 

25 def encrypt(self, data): 

26 i = j = 0 

27 out=bytearray() 

28 for char in bytearray(data): 

29 i = (i+1) & 0xff 

30 j = (j+self.state[i]) & 0xff 

31 self.state[i],self.state[j] = self.state[j],self.state[i] # SSWAP(i,j) 

32 out.append(char ^ self.state[(self.state[i] + self.state[j]) & 0xff]) 

33 

34 return bytes(out) 

35 

36 def decrypt(self, data): 

37 # It's symmetric 

38 return self.encrypt(data)