| 0,0 → 1,186 |
|---|
| # S-box lookup table calculated from the field F_{2^8} = Z_2[x]/x^8+x^4+x^3+x+1 |
| # 0 1 2 3 4 5 6 7 8 9 A B C D E F |
| s_box = [[0x63,0x7C,0x77,0x7B,0xF2,0x6B,0x6F,0xC5,0x30,0x01,0x67,0x2B,0xFE,0xD7,0xAB,0x76],#0 |
| [0XCA,0X82,0XC9,0X7D,0XFA,0X59,0X47,0XF0,0XAD,0XD4,0XA2,0XAF,0X9C,0XA4,0X72,0XC0],#1 |
| [0XB7,0XFD,0X93,0X26,0X36,0X3F,0XF7,0XCC,0X34,0XA5,0XE5,0XF1,0X71,0XD8,0X31,0X15],#1 |
| [0x04,0xC7,0x23,0xC3,0x18,0x96,0x05,0x9A,0x07,0x12,0x80,0xE2,0xEB,0x27,0xB2,0x75],#3 |
| [0x09,0x83,0x2C,0x1A,0x1B,0x6E,0x5A,0xA0,0x52,0x3B,0xD6,0xB3,0x29,0xE3,0x2F,0x84],#4 |
| [0x53,0xD1,0x00,0xED,0x20,0xFC,0xB1,0x5B,0x6A,0xCB,0xBE,0x39,0x4A,0x4C,0x58,0xCF],#5 |
| [0xD0,0xEF,0xAA,0xFB,0x43,0x4D,0x33,0x85,0x45,0xF9,0x02,0x7F,0x50,0x3C,0x9F,0xA8],#6 |
| [0x51,0xA3,0x40,0x8F,0x92,0x9D,0x38,0xF5,0xBC,0xB6,0xDA,0x21,0x10,0xFF,0xF3,0xD2],#7 |
| [0xCD,0x0C,0x13,0xEC,0x5F,0x97,0x44,0x17,0xC4,0xA7,0x7E,0x3D,0x64,0x5D,0x19,0x73],#8 |
| [0x60,0x81,0x4F,0xDC,0x22,0x2A,0x90,0x88,0x46,0xEE,0xB8,0x14,0xDE,0x5E,0x0B,0xDB],#9 |
| [0xE0,0x32,0x3A,0x0A,0x49,0x06,0x24,0x5C,0xC2,0xD3,0xAC,0x62,0x91,0x95,0xE4,0x79],#A |
| [0xE7,0xC8,0x37,0x6D,0x8D,0xD5,0x4E,0xA9,0x6C,0x56,0xF4,0xEA,0x65,0x7A,0xAE,0x08],#B |
| [0xBA,0x78,0x25,0x2E,0x1C,0xA6,0xB4,0xC6,0xE8,0xDD,0x74,0x1F,0x4B,0xBD,0x8B,0x8A],#C |
| [0x70,0x3E,0xB5,0x66,0x48,0x03,0xF6,0x0E,0x61,0x35,0x57,0xB9,0x86,0xC1,0x1D,0x9E],#D |
| [0xE1,0xF8,0x98,0x11,0x69,0xD9,0x8E,0x94,0x9B,0x1E,0x87,0xE9,0xCE,0x55,0x28,0xDF],#E |
| [0x8C,0xA1,0x89,0x0D,0xBF,0xE6,0x42,0x68,0x41,0x99,0x2D,0x0F,0xB0,0x54,0xBB,0x16]]#F |
| |
| # Key expansion lookup table |
| RCon = [[0x01,0x00,0x00,0x00],[0x02,0x00,0x00,0x00],[0x04,0x00,0x00,0x00],[0x08,0x00,0x00,0x00], |
| [0x10,0x00,0x00,0x00],[0x20,0x00,0x00,0x00],[0x40,0x00,0x00,0x00],[0x80,0x00,0x00,0x00], |
| [0x1B,0x00,0x00,0x00],[0x36,0x00,0x00,0x00]] |
| |
| # Encryption key |
| encryption_key = [0x2B,0x7E,0x15,0x16,0x28,0xAE,0xD2,0xA6,0xAB,0xF7,0x15,0x88,0x09,0xCF,0x4F,0x3C] |
| |
| # Input plaintext |
| plaintext = [0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF] |
| |
| def RotWord(byte_array): |
| '''Takes a list of bytes and cyclic left shifts it by one.''' |
| byte_array.append(byte_array.pop(0)) |
| return byte_array |
| |
| def SubBytes(byte_array): |
| '''Substitutes each byte in the given list with the value in the s-box.''' |
| for i in range(len(byte_array)): |
| byte_array[i] = s_box[(byte_array[i]&0xF0)>>4][byte_array[i]&0xF] |
| return byte_array |
| |
| def XorBytes(byte_array,input): |
| '''XORs two byte arrays and returns the result.''' |
| for i in range(len(byte_array)): |
| byte_array[i] ^= input[i] |
| return byte_array |
| |
| def ShiftRows(byte_array): |
| '''Shifts the second row left by one, the third row by two, and the fourth row by three.''' |
| # Shift second row |
| temp = byte_array[1] |
| byte_array[1] = byte_array[5] |
| byte_array[5] = byte_array[9] |
| byte_array[9] = byte_array[13] |
| byte_array[13] = temp |
| # Shift third row |
| temp = byte_array[2] |
| byte_array[2] = byte_array[10] |
| byte_array[10] = temp |
| temp = byte_array[6] |
| byte_array[6] = byte_array[14] |
| byte_array[14] = temp |
| # Shift fourth row |
| temp = byte_array[3] |
| byte_array[3] = byte_array[15] |
| byte_array[15] = byte_array[11] |
| byte_array[11] = byte_array[7] |
| byte_array[7] = temp |
| return byte_array |
| |
| def MC_Mul(byte,mul): |
| '''Helper function for MixColumns''' |
| if mul == 2: |
| byte <<= 1 |
| if byte > 0xFF: |
| byte ^= 0x11B |
| elif mul == 3: |
| byte = (byte<<1)^byte |
| if byte > 0xFF: |
| byte ^= 0x11B |
| return byte |
| |
| def MixColumns(byte_array): |
| '''Mixes each column by multiplying it with a certain matrix of elements of the field F_{2^8}.''' |
| ret = [] |
| for i in [0,4,8,12]: |
| ret.append((MC_Mul(byte_array[i],2) ^ MC_Mul(byte_array[i+1],3) ^ byte_array[i+2] ^ byte_array[i+3])&0xFF) |
| ret.append((byte_array[i] ^ MC_Mul(byte_array[i+1],2) ^ MC_Mul(byte_array[i+2],3) ^ byte_array[i+3])&0xFF) |
| ret.append((byte_array[i] ^ byte_array[i+1] ^ MC_Mul(byte_array[i+2],2) ^ MC_Mul(byte_array[i+3],3))&0xFF) |
| ret.append((MC_Mul(byte_array[i],3) ^ byte_array[i+1] ^ byte_array[i+2] ^ MC_Mul(byte_array[i+3],2))&0xFF) |
| return ret |
| |
| def KeyExpansion(key): |
| '''Computes and returns the expansion key for a given encryption key.''' |
| expanded_key = [] |
| for i in range(4): |
| expanded_key.append([key[4*i],key[4*i+1],key[4*i+2],key[4*i+3]]) |
| for i in range(4,44): |
| temp = list(expanded_key[i-1]) |
| if i % 4 == 0: |
| temp = XorBytes(SubBytes(RotWord(temp)),RCon[(i/4)-1]) |
| expanded_key.append(XorBytes(list(expanded_key[i-4]),temp)) |
| return expanded_key |
| |
| def RoundKey(expansion_key,round): |
| '''Computes and returns the round key given the expansion key.''' |
| round_key = [] |
| for i in range(4): |
| for j in range(4): |
| round_key.append(expansion_key[4*round+i][j]) |
| return round_key |
| |
| if __name__ == '__main__': |
| # Calculate and print out the round keys |
| expansion_key = KeyExpansion(encryption_key) |
| for i in range(11): |
| round_key = RoundKey(expansion_key, i) |
| print "Round Key %d:" % i, |
| for j in range(16): |
| print "%02X" % round_key[j], |
| print |
| print |
| |
| # Print out round 0 info |
| state = list(plaintext) |
| print "Initial state = plaintext:\t", |
| for i in range(16): |
| print "%02X" % state[i], |
| print |
| |
| print "Round 0 (Add Round Key 0):\t", |
| state = XorBytes(state, RoundKey(expansion_key, 0)) |
| for i in range(16): |
| print "%02X" % state[i], |
| print "\n" |
| |
| # Print out the results of each round |
| for i in range(1,10): |
| print "Round %d (SubBytes):\t\t\t" % i, |
| state = SubBytes(state) |
| for j in range(16): |
| print "%02X" % state[j], |
| print |
| |
| print "Round %d (ShiftRows):\t\t" % i, |
| state = ShiftRows(state) |
| for j in range(16): |
| print "%02X" % state[j], |
| print |
| |
| print "Round %d (MixColumns):\t\t" % i, |
| state = MixColumns(state) |
| for j in range(16): |
| print "%02X" % state[j], |
| print |
| |
| print "Round %d (Add Round Key %d):\t" % (i,i), |
| state = XorBytes(state, RoundKey(expansion_key, i)) |
| for j in range(16): |
| print "%02X" % state[j], |
| print "\n" |
| |
| # Print out the results for the final round |
| print "Round 10 (SubBytes):\t\t", |
| state = SubBytes(state) |
| for j in range(16): |
| print "%02X" % state[j], |
| print |
| |
| print "Round 10 (ShiftRows):\t\t", |
| state = ShiftRows(state) |
| for j in range(16): |
| print "%02X" % state[j], |
| print |
| |
| print "Round 10 (Add Round Key 10):", |
| state = XorBytes(state, RoundKey(expansion_key, 10)) |
| for j in range(16): |
| print "%02X" % state[j], |
| print "\n" |
| |
| # Print the ciphertext |
| print "Ciphertext:\t\t\t", |
| for j in range(16): |
| print "%02X" % state[j], |
| print |