PRINTcipher-Python/printcipher.py at master · xtigmh/PRINTcipher-Python · GitHub

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#!/usr/bin/env python


def num2bits(num, bitlength):
    bits = []
    for i in range(bitlength):
        bits.append(num & 1)
        num >>= 1
    return bits

def bits2num(bits):
    num = 0
    for i, x in enumerate(bits):
        assert x == 0 or x == 1
        num += (x << i)
    return num

def _update_round_counter(counter):
    t = 1 ^ counter[-1] ^ counter[-2]
    counter.pop()
    counter.insert(0, t)
    return counter

_sbox = (
    (0, 1, 3, 6, 7, 4, 5, 2),
    (0, 1, 7, 4, 3, 6, 5, 2),
    (0, 3, 1, 6, 7, 5, 4, 2),
    (0, 7, 3, 5, 1, 4, 6, 2),
)


def enc(plaintext, long_key, short_key, block_bits = 48):
    # compute length for counter
    if block_bits == 48:
        counter = [0, 0, 0, 0, 0, 0]
    elif block_bits == 96:
        counter = [0, 0, 0, 0, 0, 0, 0]
    else:
        import sys
        sys.stderr.write("ERROR: invalid block_bits\n")
        sys.exit(-1)

    text = num2bits(plaintext, block_bits)
    round_key = num2bits(long_key, block_bits)
    perm_key = num2bits(short_key, block_bits * 2 / 3)

    state = [None] * block_bits # temp variable
    for round_i in range(block_bits):
        # key xor
        for i in range(block_bits):
            text[i] ^= round_key[i]

        # linear diffusion
        for i in range(block_bits - 1):
            state[(3 * i) % (block_bits - 1)] = text[i]
        state[block_bits - 1] = text[block_bits - 1]

        # round counter
        counter = _update_round_counter(counter)
        for i, x in enumerate(counter):
            state[i] ^= x

        # keyed sbox
        for i in range(block_bits / 3):
            before = bits2num(state[(3 * i):(3 * i + 3)])
            after = num2bits(_sbox[bits2num(perm_key[2*i : 2*i + 2])][before], 3)
            for j in range(3):
                text[3 * i + j] = after[j]


    return bits2num(text)


if __name__ == '__main__':
    plaintext = 0x4C847555C35B
    key = 0xC28895BA327B
    permkey = 0x69D2CDB6

    ciphertext = enc(plaintext, key, permkey)

    print 'plain =', hex(plaintext)
    print 'key =', hex(key)
    print 'permkey =', hex(permkey)
    print 'cipher =', hex(ciphertext)