使用 Python 实现 DES 算法
| from itertools import chain | |
| from typing import List, Tuple | |
| from .tables import * | |
| class DES: | |
| def __init__(self, key: [str, bytes]): | |
| if isinstance(key, str): | |
| key = key.encode() | |
| if len(key) > 8: | |
| key = key[8:] | |
| elif len(key) < 8: | |
| key += b"".join(b"\x00" for _ in range(8 - len(key))) | |
| key_bit_list = self._bytes_to_bit_list(key) | |
| left_half_key_block = self._transform(key_bit_list, pc1_left_table) | |
| right_half_key_block = self._transform(key_bit_list, pc1_right_table) | |
| sub_key_list = [] | |
| for round_index in range(16): | |
| left_half_key_block = self._circle_left_shift(left_half_key_block, key_left_shift_bits[round_index]) | |
| right_half_key_block = self._circle_left_shift(right_half_key_block, key_left_shift_bits[round_index]) | |
| sub_key_list.append(self._transform(left_half_key_block + right_half_key_block, pc2_table)) | |
| self._sub_key_list = sub_key_list | |
| def encrypt(self, plain_text: [str, bytes]): | |
| if isinstance(plain_text, str): | |
| plain_text = plain_text.encode() | |
| plain_text_len = len(plain_text) | |
| if plain_text_len % 8: | |
| plain_text += b"".join(b"\x00" for _ in range(8 - plain_text_len % 8)) | |
| encrypted_blocks = [] | |
| for block in map(lambda s: plain_text[s:s + 8], range(0, plain_text_len, 8)): | |
| encrypted_blocks.append(self._encrypt_block(self._bytes_to_bit_list(block))) | |
| encrypted_bit_list = list(chain(*encrypted_blocks)) | |
| return self._bit_list_to_bytes(encrypted_bit_list) | |
| def decrypt(self, cipher_text: bytes) -> str: | |
| self._sub_key_list.reverse() | |
| plain_text = self.encrypt(cipher_text) | |
| self._sub_key_list.reverse() | |
| return plain_text.decode().rstrip('\0') | |
| def _encrypt_block(self, plain_block: List[int]) -> List[int]: | |
| plain_block = self._transform(plain_block, ip_table) | |
| left_half_block = plain_block[:32] | |
| right_half_block = plain_block[32:] | |
| for round_index in range(16): | |
| left_half_block, right_half_block = right_half_block, \ | |
| self._bit_list_xor( | |
| left_half_block, | |
| self._transform( | |
| self._s_box_transform( | |
| self._bit_list_xor( | |
| self._transform(right_half_block, | |
| extend_table), | |
| self._sub_key_list[round_index] | |
| ) | |
| ), p_table | |
| ) | |
| ) | |
| return self._transform(right_half_block + left_half_block, fp_table) | |
| @staticmethod | |
| def _transform(raw_list: list, transform_table: List[int]) -> list: | |
| return list(map(lambda index: raw_list[index], transform_table)) | |
| @staticmethod | |
| def _bytes_to_bit_list(input_bytes: bytes) -> List[int]: | |
| bit_list = [0] * 8 * len(input_bytes) | |
| index = 0 | |
| for char_ascii in input_bytes: | |
| loc = 7 | |
| while loc >= 0: | |
| bit_list[index] = 0 if char_ascii & (1 << loc) == 0 else 1 | |
| loc -= 1 | |
| index += 1 | |
| return bit_list | |
| @staticmethod | |
| def _bit_list_to_bytes(bit_list: List[int]) -> bytes: | |
| char_ascii = 0 | |
| byte_list = [] | |
| for index, bit in enumerate(bit_list): | |
| char_ascii += bit << (7 - index % 8) | |
| if index % 8 == 7: | |
| byte_list.append(char_ascii) | |
| char_ascii = 0 | |
| return bytes(byte_list) | |
| @staticmethod | |
| def _circle_left_shift(input_list: list, bits: int) -> list: | |
| return input_list[bits:] + input_list[:bits] | |
| @staticmethod | |
| def _bit_list_xor(left: list, right: list) -> List[str]: | |
| return list(map(lambda x, y: x ^ y, left, right)) | |
| @staticmethod | |
| def _s_box_transform(input_list: list) -> list: | |
| transformed = [0 for _ in range(32)] | |
| transformed_index = 0 | |
| r = 0 | |
| while r < 48: | |
| m = (input_list[r] << 1) + input_list[r + 5] | |
| n = (input_list[r + 1] << 3) + (input_list[r + 2] << 2) + (input_list[r + 3] << 1) + (input_list[r + 4]) | |
| s_value = s_box_tables[r // 6][(m << 4) + n] | |
| transformed[transformed_index] = (s_value & 8) >> 3 | |
| transformed[transformed_index + 1] = (s_value & 4) >> 2 | |
| transformed[transformed_index + 2] = (s_value & 2) >> 1 | |
| transformed[transformed_index + 3] = s_value & 1 | |
| r += 6 | |
| transformed_index += 4 | |
| return transformed |
| ip_table = [57, 49, 41, 33, 25, 17, 9, 1, | |
| 59, 51, 43, 35, 27, 19, 11, 3, | |
| 61, 53, 45, 37, 29, 21, 13, 5, | |
| 63, 55, 47, 39, 31, 23, 15, 7, | |
| 56, 48, 40, 32, 24, 16, 8, 0, | |
| 58, 50, 42, 34, 26, 18, 10, 2, | |
| 60, 52, 44, 36, 28, 20, 12, 4, | |
| 62, 54, 46, 38, 30, 22, 14, 6] | |
| fp_table = [39, 7, 47, 15, 55, 23, 63, 31, | |
| 38, 6, 46, 14, 54, 22, 62, 30, | |
| 37, 5, 45, 13, 53, 21, 61, 29, | |
| 36, 4, 44, 12, 52, 20, 60, 28, | |
| 35, 3, 43, 11, 51, 19, 59, 27, | |
| 34, 2, 42, 10, 50, 18, 58, 26, | |
| 33, 1, 41, 9, 49, 17, 57, 25, | |
| 32, 0, 40, 8, 48, 16, 56, 24] | |
| extend_table = [31, 0, 1, 2, 3, 4, | |
| 3, 4, 5, 6, 7, 8, | |
| 7, 8, 9, 10, 11, 12, | |
| 11, 12, 13, 14, 15, 16, | |
| 15, 16, 17, 18, 19, 20, | |
| 19, 20, 21, 22, 23, 24, | |
| 23, 24, 25, 26, 27, 28, | |
| 27, 28, 29, 30, 31, 0] | |
| pc1_left_table = [56, 48, 40, 32, 24, 16, 8, | |
| 0, 57, 49, 41, 33, 25, 17, | |
| 9, 1, 58, 50, 42, 34, 26, | |
| 18, 10, 2, 59, 51, 43, 35] | |
| pc1_right_table = [62, 54, 46, 38, 30, 22, 14, | |
| 6, 61, 53, 45, 37, 29, 21, | |
| 13, 5, 60, 52, 44, 36, 28, | |
| 20, 12, 4, 27, 19, 11, 3] | |
| pc2_table = [13, 16, 10, 23, 0, 4, | |
| 2, 27, 14, 5, 20, 9, | |
| 22, 18, 11, 3, 25, 7, | |
| 15, 6, 26, 19, 12, 1, | |
| 40, 51, 30, 36, 46, 54, | |
| 29, 39, 50, 44, 32, 47, | |
| 43, 48, 38, 55, 33, 52, | |
| 45, 41, 49, 35, 28, 31] | |
| key_left_shift_bits = [1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1] | |
| p_table = [15, 6, 19, 20, | |
| 28, 11, 27, 16, | |
| 0, 14, 22, 25, | |
| 4, 17, 30, 9, | |
| 1, 7, 23, 13, | |
| 31, 26, 2, 8, | |
| 18, 12, 29, 5, | |
| 21, 10, 3, 24] | |
| s_box_tables = [[14, 4, 13, 1, 2, 15, 11, 8, 3, 10, 6, 12, 5, 9, 0, 7, | |
| 0, 15, 7, 4, 14, 2, 13, 1, 10, 6, 12, 11, 9, 5, 3, 8, | |
| 4, 1, 14, 8, 13, 6, 2, 11, 15, 12, 9, 7, 3, 10, 5, 0, | |
| 15, 12, 8, 2, 4, 9, 1, 7, 5, 11, 3, 14, 10, 0, 6, 13], | |
| [15, 1, 8, 14, 6, 11, 3, 4, 9, 7, 2, 13, 12, 0, 5, 10, | |
| 3, 13, 4, 7, 15, 2, 8, 14, 12, 0, 1, 10, 6, 9, 11, 5, | |
| 0, 14, 7, 11, 10, 4, 13, 1, 5, 8, 12, 6, 9, 3, 2, 15, | |
| 13, 8, 10, 1, 3, 15, 4, 2, 11, 6, 7, 12, 0, 5, 14, 9], | |
| [10, 0, 9, 14, 6, 3, 15, 5, 1, 13, 12, 7, 11, 4, 2, 8, | |
| 13, 7, 0, 9, 3, 4, 6, 10, 2, 8, 5, 14, 12, 11, 15, 1, | |
| 13, 6, 4, 9, 8, 15, 3, 0, 11, 1, 2, 12, 5, 10, 14, 7, | |
| 1, 10, 13, 0, 6, 9, 8, 7, 4, 15, 14, 3, 11, 5, 2, 12, | |
| ], | |
| [7, 13, 14, 3, 0, 6, 9, 10, 1, 2, 8, 5, 11, 12, 4, 15, | |
| 13, 8, 11, 5, 6, 15, 0, 3, 4, 7, 2, 12, 1, 10, 14, 9, | |
| 10, 6, 9, 0, 12, 11, 7, 13, 15, 1, 3, 14, 5, 2, 8, 4, | |
| 3, 15, 0, 6, 10, 1, 13, 8, 9, 4, 5, 11, 12, 7, 2, 14], | |
| [2, 12, 4, 1, 7, 10, 11, 6, 8, 5, 3, 15, 13, 0, 14, 9, | |
| 14, 11, 2, 12, 4, 7, 13, 1, 5, 0, 15, 10, 3, 9, 8, 6, | |
| 4, 2, 1, 11, 10, 13, 7, 8, 15, 9, 12, 5, 6, 3, 0, 14, | |
| 11, 8, 12, 7, 1, 14, 2, 13, 6, 15, 0, 9, 10, 4, 5, 3], | |
| [12, 1, 10, 15, 9, 2, 6, 8, 0, 13, 3, 4, 14, 7, 5, 11, | |
| 10, 15, 4, 2, 7, 12, 9, 5, 6, 1, 13, 14, 0, 11, 3, 8, | |
| 9, 14, 15, 5, 2, 8, 12, 3, 7, 0, 4, 10, 1, 13, 11, 6, | |
| 4, 3, 2, 12, 9, 5, 15, 10, 11, 14, 1, 7, 6, 0, 8, 13], | |
| [4, 11, 2, 14, 15, 0, 8, 13, 3, 12, 9, 7, 5, 10, 6, 1, | |
| 13, 0, 11, 7, 4, 9, 1, 10, 14, 3, 5, 12, 2, 15, 8, 6, | |
| 1, 4, 11, 13, 12, 3, 7, 14, 10, 15, 6, 8, 0, 5, 9, 2, | |
| 6, 11, 13, 8, 1, 4, 10, 7, 9, 5, 0, 15, 14, 2, 3, 12], | |
| [13, 2, 8, 4, 6, 15, 11, 1, 10, 9, 3, 14, 5, 0, 12, 7, | |
| 1, 15, 13, 8, 10, 3, 7, 4, 12, 5, 6, 11, 0, 14, 9, 2, | |
| 7, 11, 4, 1, 9, 12, 14, 2, 0, 6, 10, 13, 15, 3, 5, 8, | |
| 2, 1, 14, 7, 4, 10, 8, 13, 15, 12, 9, 0, 3, 5, 6, 11]] |
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