TVqrq44f

1def str_to_hex_tuple(key, max_length=5):
2    try:
3        key = int(key)
4    except ValueError:
5        print('[E:] input cannot be parsed to number - "%s"' % key)
6        raise
7
8    bin_key = bin(key)[2:].zfill(pow(2, max_length) + 8)
9    out = []
10    for bin_pos in range(0, (max_length)*8, 8):
11        str_byte = bin_key[bin_pos:][:8]
12        byte = int(str_byte, 2)
13        out.append(byte)
14
15    return tuple(out)
16
17def hex_format_int_stream(stream):
18    return ' '.join("{:02x}".format(c) for c in stream)
19
20def rc4_keystream(key, length=484):
21
22    # Stage 1 - Init S
23    x = 0
24    S = list(range(256))
25    for i in range(256):
26        x = (x + S[i] + key[i % len(key)]) % 256
27        S[i], S[x] = S[x], S[i]
28
29    # Stage 2 - generate
30    x = y = 0
31    out = []
32    for i in range(length):
33        x = (x + 1) % 256
34        y = (y + S[x]) % 256
35        S[x], S[y] = S[y], S[x]
36        out.append(S[(S[x] + S[y]) % 256])
37
38    return out
39
40if __name__ == '__main__':
41
42    # Set variables
43    SECRET_KEY = str_to_hex_tuple('00055', max_length=5) # '55' - 40 bit
44    IV = str_to_hex_tuple('00000000', max_length=8)      # 64 bit
45
46    print('SECRET_KEY: ', hex_format_int_stream(SECRET_KEY))
47    print('IV: ', hex_format_int_stream(IV))
48
49    bstream = rc4_keystream(SECRET_KEY + IV)
50    # Drop 256 bit / 8 -> 32 bytes
51    bstream = bstream[32:]
52
53    # Display RC4 keystream
54    print(hex_format_int_stream(bstream))