#!/usr/bin/env python3 ''' ---- encrypt ---- ''' sbox = (0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76 , 0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0 , 0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15 , 0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75 , 0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84 , 0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b, 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf , 0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8 , 0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2 , 0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73 , 0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb , 0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c, 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79 , 0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08 , 0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a , 0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e , 0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf , 0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16) sigma_table = [0, 16, 32, 48, 1, 17, 33, 49, 2, 18, 34, 50, 3, 19, 35, 51, 4, 20, 36, 52, 5, 21, 37, 53, 6, 22, 38, 54, 7, 23, 39, 55, 8, 24, 40, 56, 9, 25, 41, 57, 10, 26, 42, 58, 11, 27, 43, 59, 12, 28, 44, 60, 13, 29, 45, 61, 14, 30, 46, 62, 15, 31, 47, 63] def apply_sbox(word, bytes=8): """ apply the sbox to every nibble """ word_new = 0 for i in range(bytes): # 16 nibbles byte = (word >> (i * 8)) & 0xFF # retrieve the ith nibble # insert the permuted nibble in the correct position word_new |= sbox[byte] << i * 8 return word_new def sigma(word): """ Implementing the sigma permutation on the 64 bit word . """ new_word = 0 for i in range(64): # bit position i moves to the position of sigma_table[i] new_word |= ((word >> i) & 0b1) << sigma_table[i] return new_word def f(word): return sigma(apply_sbox(word)) def round_function(word, key): return f(word) ^ key def rotate_left(word, n, word_size=64): mask = 2 ** word_size - 1 return ((word << n) & mask) | (word >> (word_size - n) & mask) def compute_roundkeys(key, rounds): key_parts = [key] for i in range(1, rounds): # cyclic shift by 15 bits, and xor by 3 rk = rotate_left(key_parts[i - 1], 15) key_parts.append(rk ^ 0b11) return key_parts def encrypt(word, key, rounds=12): round_keys = compute_roundkeys(key, rounds) for i in range(rounds): word = round_function(word, round_keys[i]) return word ''' ---- decrypt ---- ''' reverse_sbox = [sbox.index(i) for i in range(256)] reverse_sigma_table = [sigma_table.index(i) for i in range(64)] def apply_reverse_sbox(word, bytes=8): word_new = 0 for i in range(bytes): # 16 nibbles byte = (word >> (i * 8)) & 0xFF # retrieve the ith permuted nibble # retrieve back the unpermuted nibble word_new |= reverse_sbox[byte] << i * 8 return word_new def reverse_sigma(word): new_word = 0 for i in range(64): # bit position i (sigma(j)) moves back to the position of reverse_sigma_table[i] (j) new_word |= ((word >> i) & 0b1) << reverse_sigma_table[i] return new_word def reverse_f(word): return apply_reverse_sbox(reverse_sigma(word)) def reverse_round_function(word, key): return reverse_f(word ^ key) def decrypt(word, key, rounds=12): round_keys = compute_roundkeys(key, rounds) round_keys.reverse() for i in range(rounds): word = reverse_round_function(word, round_keys[i]) return word def test_vectors(): # first test the sigma function assert sigma(0x0000000000000000) == 0x0000000000000000 assert sigma(0x8000) == 0x0008000000000000 assert sigma(0xF000) == 0x0008000800080008 assert sigma(0xFFFFFFFFFFFFFFFF) == 0xFFFFFFFFFFFFFFFF # test the sbox assert apply_sbox(0x0000000000000000) & 0xFFFFFFFFFFFFFFFF == 0x6363636363636363 assert apply_sbox(0x0123456789ABCDEF) & 0xFFFFFFFFFFFFFFFF == 0x7C266E85A762BDDF, "{:016X}".format(apply_sbox(0x0123456789ABCDEF)) assert apply_sbox(0x789A147132BCFDFA) & 0xFFFFFFFFFFFFFFFF == 0xBCB8FAA32365542D # test the invertibility assert decrypt(encrypt(0xFFFFFFFFFFFFFFFF, 0), 0) & 0xFFFFFFFFFFFFFFFF == 0xFFFFFFFFFFFFFFFF assert decrypt(encrypt(0xF4F31255F4F31255, 0x123), 0x123) & 0xFFFFFFFFFFFFFFFF == 0xF4F31255F4F31255 return def generate_testvectors(): p, k = 0, 0 c = encrypt(p, k) print("E(p=%016X,k=%016X)=%016X" % (p, k, c)) p, k = 0x123456789ABCDEF0, 0x1234567890ABCDEF c = encrypt(p, k) print("E(p=%016X,k=%016X)=%016X" % (p, k, c)) return if __name__ == "__main__": import sys import random if len(sys.argv) not in [3, 4]: print("Error occured %d"%(len(sys.argv))) exit() key = int(sys.argv[1], 16) rounds = int(sys.argv[2]) if len(sys.argv) == 4: delta_in = int(sys.argv[3], 16) nrof_pairs = 2**10 print("# %s %d rounds"%(sys.argv[0], rounds)) for i in range(nrof_pairs): word = random.getrandbits(64) cipher = encrypt(word, key, rounds=rounds) if len(sys.argv) == 3: print("%016X %016X"%(word, cipher)) else: word_2 = word ^ delta_in cipher_2 = encrypt(word_2, key, rounds=rounds) print("%016X %016X %016X %016X"%(word, word_2, cipher, cipher_2))