#!/usr/bin/env python """ Copyright (C) 2012 Bo Zhu http://about.bozhu.me Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. Modified by Mystiz so that: 1. the code is now Python 3 compatible, and 2. the __add_round_key, __sub_bytes, __shift_rows, __mix_columns can be modified outside. """ 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, ) InvSbox = ( 0x52, 0x09, 0x6A, 0xD5, 0x30, 0x36, 0xA5, 0x38, 0xBF, 0x40, 0xA3, 0x9E, 0x81, 0xF3, 0xD7, 0xFB, 0x7C, 0xE3, 0x39, 0x82, 0x9B, 0x2F, 0xFF, 0x87, 0x34, 0x8E, 0x43, 0x44, 0xC4, 0xDE, 0xE9, 0xCB, 0x54, 0x7B, 0x94, 0x32, 0xA6, 0xC2, 0x23, 0x3D, 0xEE, 0x4C, 0x95, 0x0B, 0x42, 0xFA, 0xC3, 0x4E, 0x08, 0x2E, 0xA1, 0x66, 0x28, 0xD9, 0x24, 0xB2, 0x76, 0x5B, 0xA2, 0x49, 0x6D, 0x8B, 0xD1, 0x25, 0x72, 0xF8, 0xF6, 0x64, 0x86, 0x68, 0x98, 0x16, 0xD4, 0xA4, 0x5C, 0xCC, 0x5D, 0x65, 0xB6, 0x92, 0x6C, 0x70, 0x48, 0x50, 0xFD, 0xED, 0xB9, 0xDA, 0x5E, 0x15, 0x46, 0x57, 0xA7, 0x8D, 0x9D, 0x84, 0x90, 0xD8, 0xAB, 0x00, 0x8C, 0xBC, 0xD3, 0x0A, 0xF7, 0xE4, 0x58, 0x05, 0xB8, 0xB3, 0x45, 0x06, 0xD0, 0x2C, 0x1E, 0x8F, 0xCA, 0x3F, 0x0F, 0x02, 0xC1, 0xAF, 0xBD, 0x03, 0x01, 0x13, 0x8A, 0x6B, 0x3A, 0x91, 0x11, 0x41, 0x4F, 0x67, 0xDC, 0xEA, 0x97, 0xF2, 0xCF, 0xCE, 0xF0, 0xB4, 0xE6, 0x73, 0x96, 0xAC, 0x74, 0x22, 0xE7, 0xAD, 0x35, 0x85, 0xE2, 0xF9, 0x37, 0xE8, 0x1C, 0x75, 0xDF, 0x6E, 0x47, 0xF1, 0x1A, 0x71, 0x1D, 0x29, 0xC5, 0x89, 0x6F, 0xB7, 0x62, 0x0E, 0xAA, 0x18, 0xBE, 0x1B, 0xFC, 0x56, 0x3E, 0x4B, 0xC6, 0xD2, 0x79, 0x20, 0x9A, 0xDB, 0xC0, 0xFE, 0x78, 0xCD, 0x5A, 0xF4, 0x1F, 0xDD, 0xA8, 0x33, 0x88, 0x07, 0xC7, 0x31, 0xB1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xEC, 0x5F, 0x60, 0x51, 0x7F, 0xA9, 0x19, 0xB5, 0x4A, 0x0D, 0x2D, 0xE5, 0x7A, 0x9F, 0x93, 0xC9, 0x9C, 0xEF, 0xA0, 0xE0, 0x3B, 0x4D, 0xAE, 0x2A, 0xF5, 0xB0, 0xC8, 0xEB, 0xBB, 0x3C, 0x83, 0x53, 0x99, 0x61, 0x17, 0x2B, 0x04, 0x7E, 0xBA, 0x77, 0xD6, 0x26, 0xE1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0C, 0x7D, ) # learnt from http://cs.ucsb.edu/~koc/cs178/projects/JT/aes.c xtime = lambda a: (((a << 1) ^ 0x1B) & 0xFF) if (a & 0x80) else (a << 1) Rcon = ( 0x00, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1B, 0x36, 0x6C, 0xD8, 0xAB, 0x4D, 0x9A, 0x2F, 0x5E, 0xBC, 0x63, 0xC6, 0x97, 0x35, 0x6A, 0xD4, 0xB3, 0x7D, 0xFA, 0xEF, 0xC5, 0x91, 0x39, ) def text2matrix(text): text = int.from_bytes(text, 'big') matrix = [] for i in range(16): byte = (text >> (8 * (15 - i))) & 0xFF if i % 4 == 0: matrix.append([byte]) else: matrix[i // 4].append(byte) return matrix def matrix2text(matrix): text = 0 for i in range(4): for j in range(4): text |= (matrix[i][j] << (120 - 8 * (4 * i + j))) return text.to_bytes(16, 'big') class AES: def __init__(self, master_key): self.change_key(master_key) def change_key(self, master_key): self.round_keys = text2matrix(master_key) for i in range(4, 4 * 11): self.round_keys.append([]) if i % 4 == 0: byte = self.round_keys[i - 4][0] \ ^ Sbox[self.round_keys[i - 1][1]] \ ^ Rcon[i // 4] self.round_keys[i].append(byte) for j in range(1, 4): byte = self.round_keys[i - 4][j] \ ^ Sbox[self.round_keys[i - 1][(j + 1) % 4]] self.round_keys[i].append(byte) else: for j in range(4): byte = self.round_keys[i - 4][j] \ ^ self.round_keys[i - 1][j] self.round_keys[i].append(byte) def encrypt(self, plaintext): self.plain_state = text2matrix(plaintext) self._add_round_key(self.plain_state, self.round_keys[:4]) for i in range(1, 10): self._round_encrypt(self.plain_state, self.round_keys[4 * i : 4 * (i + 1)]) self._sub_bytes(self.plain_state) self._shift_rows(self.plain_state) self._add_round_key(self.plain_state, self.round_keys[40:]) return matrix2text(self.plain_state) def decrypt(self, ciphertext): self.cipher_state = text2matrix(ciphertext) self._add_round_key(self.cipher_state, self.round_keys[40:]) self._inv_shift_rows(self.cipher_state) self._inv_sub_bytes(self.cipher_state) for i in range(9, 0, -1): self._round_decrypt(self.cipher_state, self.round_keys[4 * i : 4 * (i + 1)]) self._add_round_key(self.cipher_state, self.round_keys[:4]) return matrix2text(self.cipher_state) def _add_round_key(self, s, k): for i in range(4): for j in range(4): s[i][j] ^= k[i][j] def _round_encrypt(self, state_matrix, key_matrix): self._sub_bytes(state_matrix) self._shift_rows(state_matrix) self._mix_columns(state_matrix) self._add_round_key(state_matrix, key_matrix) def _round_decrypt(self, state_matrix, key_matrix): self._add_round_key(state_matrix, key_matrix) self._inv_mix_columns(state_matrix) self._inv_shift_rows(state_matrix) self._inv_sub_bytes(state_matrix) def _sub_bytes(self, s): for i in range(4): for j in range(4): s[i][j] = Sbox[s[i][j]] def _inv_sub_bytes(self, s): for i in range(4): for j in range(4): s[i][j] = InvSbox[s[i][j]] def _shift_rows(self, s): s[0][1], s[1][1], s[2][1], s[3][1] = s[1][1], s[2][1], s[3][1], s[0][1] s[0][2], s[1][2], s[2][2], s[3][2] = s[2][2], s[3][2], s[0][2], s[1][2] s[0][3], s[1][3], s[2][3], s[3][3] = s[3][3], s[0][3], s[1][3], s[2][3] def _inv_shift_rows(self, s): s[0][1], s[1][1], s[2][1], s[3][1] = s[3][1], s[0][1], s[1][1], s[2][1] s[0][2], s[1][2], s[2][2], s[3][2] = s[2][2], s[3][2], s[0][2], s[1][2] s[0][3], s[1][3], s[2][3], s[3][3] = s[1][3], s[2][3], s[3][3], s[0][3] def _mix_single_column(self, a): # please see Sec 4.1.2 in The Design of Rijndael t = a[0] ^ a[1] ^ a[2] ^ a[3] u = a[0] a[0] ^= t ^ xtime(a[0] ^ a[1]) a[1] ^= t ^ xtime(a[1] ^ a[2]) a[2] ^= t ^ xtime(a[2] ^ a[3]) a[3] ^= t ^ xtime(a[3] ^ u) def _mix_columns(self, s): for i in range(4): self._mix_single_column(s[i]) def _inv_mix_columns(self, s): # see Sec 4.1.3 in The Design of Rijndael for i in range(4): u = xtime(xtime(s[i][0] ^ s[i][2])) v = xtime(xtime(s[i][1] ^ s[i][3])) s[i][0] ^= u s[i][1] ^= v s[i][2] ^= u s[i][3] ^= v self._mix_columns(s)