| # ------------------------------------------------------------------------------ |
| # |
| # SHA-512-BASED FEISTEL CIPHER |
| # by Toni Mattis |
| # |
| # Feistel Function: SHA-512(Block || Key) |
| # Key Size: Fully Dynamic |
| # Block Size: 1024 Bits |
| # Rounds: User-Specified |
| # |
| # ------------------------------------------------------------------------------ |
| |
| from hashlib import sha512 |
| |
| BPOS = tuple(range(64)) |
| |
| def enc_block(block, key, rounds = 16): |
| x = block[:64] |
| y = block[64:] |
| for i in xrange(rounds): |
| h = sha512(x + key).digest() |
| y = ''.join([chr(ord(y[k]) ^ ord(h[k])) for k in BPOS]) |
| h = sha512(y + key).digest() |
| x = ''.join([chr(ord(x[k]) ^ ord(h[k])) for k in BPOS]) |
| return x + y |
| |
| def dec_block(block, key, rounds = 16): |
| x = block[:64] |
| y = block[64:] |
| for i in xrange(rounds): |
| h = sha512(y + key).digest() |
| x = ''.join([chr(ord(x[k]) ^ ord(h[k])) for k in BPOS]) |
| h = sha512(x + key).digest() |
| y = ''.join([chr(ord(y[k]) ^ ord(h[k])) for k in BPOS]) |
| return x + y |
| |
| |
| |
