from operators import multiply_operator as Nb Nr Nk inv_k 0x0e 0x0b 0x

  • Anonymous
  • Python
  • 09 Jun 2014 
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from operators import multiply_operator as x



Nb = 4

Nr = 3

Nk = 4



k = [[2, 3, 1, 1],

     [1, 2, 3, 1],

     [1, 1, 2, 3],

     [3, 1, 1, 2]]



inv_k = [[0x0e,0x0b,0x0d,0x09],

         [0x09,0x0e,0x0b,0x0d],

         [0x0d,0x09,0x0e,0x0b],

         [0x0b,0x0d,0x09,0x0e]]





def get_r_const():

        return [[0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36],

                [0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00],

                [0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00],

                [0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00]]





def get_s_block(name='s.ini'):

    with open(name, 'r') as s_file:

        return [[int(elem, 16) for elem in line.strip('\n').split('\t')] for line in s_file.readlines()]





def to_block(input_bytes, nb=4):

    block = [[] for i in range(nb)]

    for row in range(4):

        for column in range(nb):

            block[row].append(input_bytes[row + 4*column])

    return block





def to_block2(input_bytes, nb=4):

    block = [[] for i in range(nb)]

    i = 0

    for row in range(4):

        for column in range(nb):

            block[row].append(input_bytes[i])

            i += 1

    return block





def from_block(block):

    output = [None for i in range(4*Nb)]

    for row in range(4):

        for column in range(Nb):

            output[row + 4*column] = hex(block[row][column])[2:].zfill(2)

    return output





def from_block2(block):

    a = [[hex(cell)[2:].zfill(2) for cell in row] for row in block]

    return a





def sub_bytes(block, s_block):

    for row in block:

        for column in range(len(row)):

            x = row[column] >> 4

            y = row[column] & 0xf

            row[column] = s_block[x][y]

    return block





def shift_rows(block):

    for row in range(len(block)):

        block[row] = block[row][row:] + block[row][:row]

    return block





def inv_shift_rows(block):

    for row in range(len(block)):

        block[row] = block[row][-row:] + block[row][:-row]

    return block





def mix_column(block, k):

    s = {}

    for column in range(len(block[0])):

        s[0] = (block[0][column] |x| k[0][0]) ^ (block[1][column] |x| k[0][1]) ^ (block[2][column] |x| k[0][2]) ^ (block[3][column] |x| k[0][3])

        s[1] = (block[0][column] |x| k[1][0]) ^ (block[1][column] |x| k[1][1]) ^ (block[2][column] |x| k[1][2]) ^ (block[3][column] |x| k[1][3])

        s[2] = (block[0][column] |x| k[2][0]) ^ (block[1][column] |x| k[2][1]) ^ (block[2][column] |x| k[2][2]) ^ (block[3][column] |x| k[2][3])

        s[3] = (block[0][column] |x| k[3][0]) ^ (block[1][column] |x| k[3][1]) ^ (block[2][column] |x| k[3][2]) ^ (block[3][column] |x| k[3][3])



        block[0][column], block[1][column], block[2][column], block[3][column] = s[0], s[1], s[2], s[3]



    return block





def add_round_key(block, key):

    for row in range(len(block)):

        for column in range(len(block[row])):

            block[row][column] ^= key[row][column]

    return block





def get_rot_word(block, index):

    rot_word = []

    for row in block:

        rot_word.append(row[index])

    return rot_word





def shift_rot_word(rot_word):

    return rot_word[1:] + rot_word[:1]





def sub_words(rot_words, s_block):

    for ind, byte in enumerate(rot_words):

        x = byte >> 4

        y = byte & 0xf

        rot_words[ind] = s_block[x][y]

    return rot_words





def key_expansion(key, s_block):

    key_schedule = key[:]

    for w in range(4, Nb*(Nr+1)):

        for row in range(4):

            if w % 4 == 0:

                rot_word = get_rot_word(key_schedule, w-1)

                rot_word = shift_rot_word(rot_word)

                rot_word = sub_words(rot_word, s_block)

                key_schedule[row] += [key_schedule[row][w-4] ^ rot_word[row] ^ get_r_const()[row][w-4]]

            else:

                key_schedule[row] += [key_schedule[row][w-1] ^ key_schedule[row][w-4]]

    return key_schedule





def key_expansion2(key, s_block):

    key_schedule = key[:]

    r_const = get_r_const()

    for w in range(4, Nb*(Nr+1)):

        key_schedule.append([])

        for column in range(4):

            if w % 4 == 0:

                rot_word = key_schedule[w-1]

                rot_word = shift_rot_word(rot_word)

                rot_word = sub_words(rot_word, s_block)

                key_schedule[w] += [key_schedule[w-4][column] ^ rot_word[column] ^ r_const[3-column][w/4-1]]

            else:

                key_schedule[w] += [key_schedule[w-1][column] ^ key_schedule[w-4][column]]

    return key_schedule





def get_round_key(key_schedule, rnd):

    key = []

    for row in key_schedule:

        key += [row[rnd*Nk:(rnd+1)*Nk]]

    return key





def crypt(input_bytes, input_key, s_block):

    block = to_block2(input_bytes)

    key = to_block2(input_key)

    key_schedule = key_expansion2(key, s_block)



    block = add_round_key(block, key)

    for i in range(1, Nr):

        block = sub_bytes(block, s_block)

        block = shift_rows(block)

        block = mix_column(block, k)

        #key = get_round_key(key_schedule, i)

        key = key_schedule[i*4:(i+1)*4]

        block = add_round_key(block, key)

    block = sub_bytes(block, s_block)

    block = shift_rows(block)

    key = key_schedule[Nr*4:(Nr+1)*4]

    #key = get_round_key(key_schedule, Nr)

    block = add_round_key(block, key)

    return block





def pretty_print(string, block):

    print string

    for i in block:

        print i





def decrypt(input_bytes, input_key):

    block = to_block2(input_bytes)

    key = to_block2(input_key)

    key_schedule = key_expansion2(key, s_block)



    pretty_print('\nAll keys', from_block2(key_schedule[:]))



    key_schedule = key_schedule[:4] + mix_column(key_schedule[4:8], inv_k) +\

                   mix_column(key_schedule[8:12], inv_k) + key_schedule[12:]

    pretty_print('\nAll keys after mix column', from_block2(key_schedule[:]))



    key = key_schedule[Nr*4:(Nr+1)*4]

    block = add_round_key(block, key)

    pretty_print('\nStep 1: add 4th key', from_block2(block))

    for i in range(Nr-1, 0, -1):

        print '\nRound: %d' % (Nr - i)

        block = sub_bytes(block, inv_s_block)

        pretty_print('Step %d: substitution bytes by s-block' %(Nr - i + 1), from_block2(block))

        block = inv_shift_rows(block)

        pretty_print('\nStep %d: shift rows' %(Nr - i + 2), from_block2(block))

        block = mix_column(block, inv_k)

        pretty_print('\nStep %d: mix column' %(Nr - i + 3), from_block2(block))

        #key = get_round_key(key_schedule, i)

        key = key_schedule[i*4:(i+1)*4]

        block = add_round_key(block, key)

        pretty_print('\nStep %d: add %dth key' %(Nr - i + 4, i+1), from_block2(block))



    print '\nRound: %d' % (Nr)

    block = sub_bytes(block, inv_s_block)

    pretty_print('Step %d: substitution bytes by s-block' %(Nr + 4), from_block2(block))



    block = inv_shift_rows(block)

    pretty_print('\nStep %d: shift rows' %(Nr + 5), from_block2(block))

    #key = get_round_key(key_schedule, Nr)

    block = add_round_key(block, key_schedule[:4])

    pretty_print('\nStep %d: add %dth key' %(Nr + 6, 1), from_block2(block))

    return block



s_block = get_s_block()

inv_s_block = get_s_block('inv_s.ini')



if __name__ == '__main__':

    input_bytes = [0x8E, 0xA5, 0xD6, 0x5A,

                   0xB4, 0xAE, 0x68, 0x93,

                   0xAB, 0x56, 0x81, 0x0B,

                   0xC0, 0x7C, 0xA5, 0x59,

                   0x8E, 0xA5, 0xD6, 0x5A,

                   0xB4, 0xAE, 0x68, 0x93,

                   0xAB, 0x56, 0x81, 0x0B,

                   0xC0, 0x7C, 0xA5, 0x59]

    input_key = [0x2f, 0x22, 0x2e, 0x27, 0x30, 0x3f, 0x2d, 0x2b, 0x2c, 0x00, 0x25, 0x27, 0x30, 0x2b, 0x2c, 0x00]



    print '\n0-16 bytes'

    a = decrypt(input_bytes[:16], input_key)

    pretty_print('\nFinal:', from_block2(a))

    print '\n', '='*70

    print '\n16-32 bytes'

    a2 = decrypt(input_bytes[16:], input_key)

    pretty_print('\nFinal:', from_block2(a2))
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