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import re
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# ========================================
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# 一、子密钥生成
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# (1) 初始置换 64->56
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# 64位的种子密钥经过PC_1置换后，生成56位的密钥
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# (2) 划分 56->(28,28)
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# 经过初始置换后的56位密钥被均分成C0和D0两部分
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# (3) 循环左移
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# 第一轮，C0和D0根据移位次数表各自进行循环左移
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# 得到C1和D1
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# 每一轮的C和D值是由上一轮的C和D值循环左移得到的
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# (4) 合并 (28,28)->56->48
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# 左移后的两部分再次合并,通过一个选择压缩表(PC_2)
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# 得到这一轮的子密钥
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# (5)重复3、4操作,最终得到16个子密钥
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# ========================================
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# 置换选择表1(PC_1) 64->56
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PC_1 = [57, 49, 41, 33, 25, 17, 9,
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1, 58, 50, 42, 34, 26, 18,
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10, 2, 59, 51, 43, 35, 27,
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19, 11, 3, 60, 52, 44, 36,
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63, 55, 47, 39, 31, 23, 15,
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7, 62, 54, 46, 38, 30, 22,
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14, 6, 61, 53, 45, 37, 29,
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21, 13, 5, 28, 20, 12, 4
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]
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# 置换选择压缩表2(PC_2) 56->48
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PC_2 = [14, 17, 11, 24, 1, 5, 3, 28,
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15, 6, 21, 10, 23, 19, 12, 4,
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26, 8, 16, 7, 27, 20, 13, 2,
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41, 52, 31, 37, 47, 55, 30, 40,
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51, 45, 33, 48, 44, 49, 39, 56,
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34, 53, 46, 42, 50, 36, 29, 32
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]
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# 移位次数表
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shift_num = [1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1]
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def pc_1_change(bin_key):
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"""初始置换
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64位的种子密钥经过PC_1置换后，生成56位的密钥
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"""
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return [bin_key[i - 1] for i in PC_1] # 列表形式
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def shift_left(bin_key, num):
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"""实现C和D的循环左移"""
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return bin_key[num:] + bin_key[:num]
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def pc_2_change(bin_key):
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"""选择压缩
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56位的密钥经过PC_2压缩，生成48位子密钥
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"""
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return ''.join([bin_key[i - 1] for i in PC_2]) # 列表转字符串
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def get_subkey_list(bin_key):
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"""生成16轮的加解子密钥"""
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subkey_list = [] # 存储16轮子密钥
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# 1. 初始置换 64->58
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temp = pc_1_change(bin_key)
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# 2. 循环左移
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for i in shift_num:
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temp[:28] = shift_left(temp[:28], i) # C部分循环左移
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temp[28:] = shift_left(temp[28:], i) # D部分循环左移
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subkey_list.append(pc_2_change(temp)) # 生成子密钥
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return subkey_list
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# ========================================
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# 二、DES加解密实现
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# ========================================
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# 初始置换表IP 64->64
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IP = [58, 50, 42, 34, 26, 18, 10, 2,
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60, 52, 44, 36, 28, 20, 12, 4,
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62, 54, 46, 38, 30, 22, 14, 6,
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64, 56, 48, 40, 32, 24, 16, 8,
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57, 49, 41, 33, 25, 17, 9, 1,
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59, 51, 43, 35, 27, 19, 11, 3,
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61, 53, 45, 37, 29, 21, 13, 5,
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63, 55, 47, 39, 31, 23, 15, 7
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]
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# 逆置换表_IP 64->64
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_IP = [40, 8, 48, 16, 56, 24, 64, 32, 39,
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7, 47, 15, 55, 23, 63, 31, 38, 6,
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46, 14, 54, 22, 62, 30, 37, 5, 45,
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13, 53, 21, 61, 29, 36, 4, 44, 12,
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52, 20, 60, 28, 35, 3, 43, 11, 51,
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19, 59, 27, 34, 2, 42, 10, 50, 18,
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58, 26, 33, 1, 41, 9, 49, 17, 57, 25
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]
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# 扩展置换表E 32->48
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E = [32, 1, 2, 3, 4, 5, 4, 5,
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6, 7, 8, 9, 8, 9, 10, 11,
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12, 13, 12, 13, 14, 15, 16, 17,
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16, 17, 18, 19, 20, 21, 20, 21,
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22, 23, 24, 25, 24, 25, 26, 27,
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28, 29, 28, 29, 30, 31, 32, 1
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]
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# S盒 48->32
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S1 = [14, 4, 13, 1, 2, 15, 11, 8, 3, 10, 6, 12, 5, 9, 0, 7,
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0, 15, 7, 4, 14, 2, 13, 1, 10, 6, 12, 11, 9, 5, 3, 8,
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4, 1, 14, 8, 13, 6, 2, 11, 15, 12, 9, 7, 3, 10, 5, 0,
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15, 12, 8, 2, 4, 9, 1, 7, 5, 11, 3, 14, 10, 0, 6, 13
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]
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S2 = [15, 1, 8, 14, 6, 11, 3, 4, 9, 7, 2, 13, 12, 0, 5, 10,
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3, 13, 4, 7, 15, 2, 8, 14, 12, 0, 1, 10, 6, 9, 11, 5,
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0, 14, 7, 11, 10, 4, 13, 1, 5, 8, 12, 6, 9, 3, 2, 15,
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13, 8, 10, 1, 3, 15, 4, 2, 11, 6, 7, 12, 0, 5, 14, 9
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]
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S3 = [10, 0, 9, 14, 6, 3, 15, 5, 1, 13, 12, 7, 11, 4, 2, 8,
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13, 7, 0, 9, 3, 4, 6, 10, 2, 8, 5, 14, 12, 11, 15, 1,
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13, 6, 4, 9, 8, 15, 3, 0, 11, 1, 2, 12, 5, 10, 14, 7,
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1, 10, 13, 0, 6, 9, 8, 7, 4, 15, 14, 3, 11, 5, 2, 12
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]
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S4 = [7, 13, 14, 3, 0, 6, 9, 10, 1, 2, 8, 5, 11, 12, 4, 15,
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13, 8, 11, 5, 6, 15, 0, 3, 4, 7, 2, 12, 1, 10, 14, 9,
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10, 6, 9, 0, 12, 11, 7, 13, 15, 1, 3, 14, 5, 2, 8, 4,
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3, 15, 0, 6, 10, 1, 13, 8, 9, 4, 5, 11, 12, 7, 2, 14
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]
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S5 = [2, 12, 4, 1, 7, 10, 11, 6, 8, 5, 3, 15, 13, 0, 14, 9,
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14, 11, 2, 12, 4, 7, 13, 1, 5, 0, 15, 10, 3, 9, 8, 6,
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4, 2, 1, 11, 10, 13, 7, 8, 15, 9, 12, 5, 6, 3, 0, 14,
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11, 8, 12, 7, 1, 14, 2, 13, 6, 15, 0, 9, 10, 4, 5, 3
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]
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S6 = [12, 1, 10, 15, 9, 2, 6, 8, 0, 13, 3, 4, 14, 7, 5, 11,
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10, 15, 4, 2, 7, 12, 9, 5, 6, 1, 13, 14, 0, 11, 3, 8,
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9, 14, 15, 5, 2, 8, 12, 3, 7, 0, 4, 10, 1, 13, 11, 6,
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4, 3, 2, 12, 9, 5, 15, 10, 11, 14, 1, 7, 6, 0, 8, 13
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]
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S7 = [4, 11, 2, 14, 15, 0, 8, 13, 3, 12, 9, 7, 5, 10, 6, 1,
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13, 0, 11, 7, 4, 9, 1, 10, 14, 3, 5, 12, 2, 15, 8, 6,
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1, 4, 11, 13, 12, 3, 7, 14, 10, 15, 6, 8, 0, 5, 9, 2,
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6, 11, 13, 8, 1, 4, 10, 7, 9, 5, 0, 15, 14, 2, 3, 12
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]
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S8 = [13, 2, 8, 4, 6, 15, 11, 1, 10, 9, 3, 14, 5, 0, 12, 7,
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1, 15, 13, 8, 10, 3, 7, 4, 12, 5, 6, 11, 0, 14, 9, 2,
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7, 11, 4, 1, 9, 12, 14, 2, 0, 6, 10, 13, 15, 3, 5, 8,
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2, 1, 14, 7, 4, 10, 8, 13, 15, 12, 9, 0, 3, 5, 6, 11
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]
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S = [S1, S2, S3, S4, S5, S6, S7, S8]
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# P盒替换 32->32
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P = [16, 7, 20, 21, 29, 12, 28, 17,
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1, 15, 23, 26, 5, 18, 31, 10,
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2, 8, 24, 14, 32, 27, 3, 9,
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19, 13, 30, 6, 22, 11, 4, 25
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]
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# encrypt
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def ip_change(bin_text):
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"""初始置换"""
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return [bin_text[i - 1] for i in IP]
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def s_box(bin_result):
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"""S盒替换"""
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int_result = []
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result = ''
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for i in range(8):
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# 二进制行号
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bin_row = bin_result[i][0] + bin_result[i][5]
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# 二进制列号
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bin_col = ''.join(bin_result[i][j] for j in range(1, 5))
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# 获取对应的十进制数
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int_result.append(S[i][16 * int(bin_row, base=2) + int(bin_col, base=2)])
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# 十进制转成二进制
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result += bin(int_result[-1])[2:].zfill(4)
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return result
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def p_box(result):
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"""P盒置换"""
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return ''.join(result[i - 1] for i in P)
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def f(R, bin_key):
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"""轮函数f()"""
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# 1.将R由32位扩展成48位
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R_ext = [R[i - 1] for i in E]
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# 2.与子密钥进行逐位异或
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bin_temp = [str(int(r) ^ int(k)) for r, k in zip(R_ext, bin_key)]
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# 6个字符为一组，共8组
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bin_result = [''.join(bin_temp[i:i + 6]) for i in range(0, len(bin_temp), 6)]
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# 3.S盒替换 48->32
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result = s_box(bin_result)
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# 4.P盒置换 32->32
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return p_box(result)
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def _ip_change(bin_text):
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"""进行IP-1逆置换"""
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return ''.join(bin_text[i - 1] for i in _IP)
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def des_cipher(bin_text, bin_key, reverse_keys=False):
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"""通用DES加密解密函数"""
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# 1. 初始置换IP
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bin_text = ip_change(bin_text)
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# 2. 分成左右两部分L、R
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L, R = bin_text[:32], bin_text[32:]
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# 3. 获得16轮子密钥
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subkey_list = get_subkey_list(bin_key)
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if reverse_keys:
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subkey_list = subkey_list[::-1] # 解密时反转子密钥列表
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# 4. 进行16轮迭代
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for i in subkey_list:
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R_temp = R
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# 轮函数f()结果和L进行异或
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R = ''.join(str(int(r) ^ int(l)) for r, l in zip(f(R, i), L))
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L = R_temp
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# 5. 进行IP-1逆置换 64->64
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return _ip_change(R + L) # 输出二进制字符串
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def bin2str(bin_text):
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"""二进制字符串转字符串"""
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# 1.将二进制字符串按8位分割，并转换为字节数组
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byte_array = bytearray(int(i, 2) for i in re.findall(r'.{8}', bin_text) if int(i, 2) != 0)
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# 2.将字节序列解码为字符串
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return byte_array.decode()
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def is_valid_key(key):
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return len(re.findall(r'.{1,16}', key)[0]) == 8 # 检查miao
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def str2bin(text):
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"""字符串转二进制字符串"""
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return ''.join(bin(byte)[2:].zfill(8) for byte in text.encode())
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def des_encrypt(plaintext, key):
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"""DES加密"""
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# 1.明文转成二进制字符串, 0填充至64的倍数
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bin_plaintext = str2bin(plaintext)
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padding_len = (64 - (len(bin_plaintext) % 64)) % 64
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bin_padding_plaintext = bin_plaintext + '0' * padding_len
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# 2.进行64位分组加密
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bin_group_64 = re.findall(r'.{64}', bin_padding_plaintext)
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bin_ciphertext = ''
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for g in bin_group_64:
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bin_ciphertext += des_cipher(g, str2bin(key))
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# 3.密文转为16进制输出
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bin_group_4 = re.findall(r'.{4}', bin_ciphertext)
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hex_ciphertext = ''
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for g in bin_group_4:
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hex_ciphertext += format(int(g, 2), 'x')
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return hex_ciphertext
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def des_decrypt(hex_ciphertext, key):
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"""DES解密"""
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# 1.16进制密文转为2进制字符串
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bin_ciphertext = ''.join(bin(int(h, 16))[2:].zfill(4) for h in hex_ciphertext)
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# 2.进行64位分组解密
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bin_group_64 = re.findall(r'.{64}', bin_ciphertext)
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bin_deciphertext = ''
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for g in bin_group_64:
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bin_deciphertext += des_cipher(g, str2bin(key), reverse_keys=True)
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# 3.将解密密文转为字符串输出
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return bin2str(bin_deciphertext)
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def des_run():
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"""DES启动界面"""
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flag = True
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while flag:
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print('=' * 3, "DES加密解密", '=' * 3)
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print('[1]加密')
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print('[2]解密')
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print('[0]退出')
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choice = input('请输入你的选择：')
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if choice == '0':
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flag = False
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elif choice == '1':
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plaintext = input('请输入明文:')
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key = input('请输入密钥(8位):')
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if not is_valid_key(key):
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print('密钥长度错误，密钥长度为8，请重新输入')
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continue
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ciphertext = des_encrypt(plaintext, key)
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print(f'密文:{ciphertext}')
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elif choice == '2':
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hex_ciphertext = input('请输入密文:')
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key = input('请输入密钥(8字节，16进制):')
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if not is_valid_key(key):
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print('密钥长度错误，请输入8个字符的16进制密钥')
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continue
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print(f'解密:{des_decrypt(hex_ciphertext, key)}')
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else:
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print('输入错误')
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print('=' * 15)
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if __name__ == '__main__':
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des_run() |
