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