DES的加密与解密算法（Python实现）

DES的加密与解密算法（Python实现）

密码学实验：实现了DES的简单的加密和解密算法，DES算法的相关资料网上很多，这里不再赘述，仅仅贴出源代码给大家分享，源码中包含很多汉字注释，相信大家都是可以读懂的。

为了方便阅读和理解DES算法的原理，这里我将代码进行了模块化，分为了四个模块：密钥生成模块、F函数模块、DES加密模块、DES解密模块。

注：DES的加密算法和解密算法几乎是一模一样的，仅仅是密钥的使用顺序不同，所以模块的代码也几乎没有什么区别。输入输出要求是16个十六进制的字符，刚好是64bit！

转载请注明出处：https://www.cnblogs.com/wangyanzhong123/p/10575739.html

密钥生成模块：

 1 MaxTime = 16
 2     #生成子密钥的置换表1，将64位的密钥转换为56位
 3 key_table1=[ 57, 49, 41, 33, 25, 17,  9,
 4               1, 58, 50, 42, 34, 26, 18,
 5              10,  2, 59, 51, 43, 35, 27,
 6              19, 11,  3, 60, 52, 44, 36,
 7              63, 55, 47, 39, 31, 23, 15,
 8               7, 62, 54, 46, 38, 30, 22,
 9              14,  6, 61, 53, 45, 37, 29,
10              21, 13,  5, 28, 20, 12,  4 ]
11     #生成子密钥的置换表2，将56位的密钥转换为48位
12 key_table2=[ 14, 17, 11, 24,  1,  5,
13               3, 28, 15,  6, 21, 10,
14              23, 19, 12,  4, 26,  8,
15              16,  7, 27, 20, 13,  2,
16              41, 52, 31, 37, 47, 55,
17              30, 40, 51, 45, 33, 48,
18              44, 49, 39, 56, 34, 53,
19              46, 42, 50, 36, 29, 32 ]
20 
21 def Listmove(l, step):    #将列表中的元素循环左移
22     return l[step:] + l[:step]
23 
24 def Subkey(key):    #生成子密钥
25     keyresult = []
26     key0 = [0 for i in range(56)]
27 
28     for i in range(len(key_table1)):
29         key0[i] = key[key_table1[i]-1]
30 
31     #生成16个密钥
32     for i in range(MaxTime):
33         key1 = [0 for i in range(48)]
34         #确定每次左移的步数
35         if (i == 0 or i == 1 or i == 8 or i == 15):
36             step = 1
37         else:
38             step = 2
39         #分成两组
40         tmp1 = key0[0:28]
41         tmp2 = key0[28:56]
42         #循环左移
43         tmp1 = Listmove(tmp1, step)
44         tmp2 = Listmove(tmp2, step)
45         #左右连接
46         key0 = tmp1 + tmp2
47         #置换选择
48         for i in range(len(key_table2)):
49             key1[i] = key0[key_table2[i]-1]
50         #生成密钥
51         keyresult.append(key1)
52     #返回的是一个集合包含了每次的密钥
53     return keyresult

F函数模块：

  1 MaxTime = 16
  2 #IP置换表
  3 IP_table=[58, 50, 42, 34, 26, 18, 10, 2,
  4           60, 52, 44, 36, 28, 20, 12, 4,
  5           62, 54, 46, 38, 30, 22, 14, 6,
  6           64, 56, 48, 40, 32, 24, 16, 8,
  7           57, 49, 41, 33, 25, 17,  9, 1,
  8           59, 51, 43, 35, 27, 19, 11, 3,
  9           61, 53, 45, 37, 29, 21, 13, 5,
 10           63, 55, 47, 39, 31, 23, 15, 7 ]
 11 #逆IP置换表
 12 Inv_IP_table=[40,  8, 48, 16, 56, 24, 64, 32,
 13               39,  7, 47, 15, 55, 23, 63, 31,
 14               38,  6, 46, 14, 54, 22, 62, 30,
 15               37,  5, 45, 13, 53, 21, 61, 29,
 16               36,  4, 44, 12, 52, 20, 60, 28,
 17               35,  3, 43, 11, 51, 19, 59, 27,
 18               34,  2, 42, 10, 50, 18, 58, 26,
 19               33,  1, 41,  9, 49, 17, 57, 25 ]
 20 #S盒中的S1盒
 21 S1=[14,  4, 13,  1,  2, 15, 11,  8,  3, 10,  6, 12,  5,  9,  0,  7,
 22      0, 15,  7,  4, 14,  2, 13,  1, 10,  6, 12, 11,  9,  5,  3,  8,
 23      4,  1, 14,  8, 13,  6,  2, 11, 15, 12,  9,  7,  3, 10,  5,  0,
 24     15, 12,  8,  2,  4,  9,  1,  7,  5, 11,  3, 14, 10,  0,  6, 13 ]
 25 #S盒中的S2盒
 26 S2=[15,  1,  8, 14,  6, 11,  3,  4,  9,  7,  2, 13, 12,  0,  5, 10,
 27      3, 13,  4,  7, 15,  2,  8, 14, 12,  0,  1, 10,  6,  9, 11,  5,
 28      0, 14,  7, 11, 10,  4, 13,  1,  5,  8, 12,  6,  9,  3,  2, 15,
 29     13,  8, 10,  1,  3, 15,  4,  2, 11,  6,  7, 12,  0,  5, 14,  9 ]
 30 #S盒中的S3盒
 31 S3=[10,  0,  9, 14,  6,  3, 15,  5,  1, 13, 12,  7, 11,  4,  2,  8,
 32     13,  7,  0,  9,  3,  4,  6, 10,  2,  8,  5, 14, 12, 11, 15,  1,
 33     13,  6,  4,  9,  8, 15,  3,  0, 11,  1,  2, 12,  5, 10, 14,  7,
 34      1, 10, 13,  0,  6,  9,  8,  7,  4, 15, 14,  3, 11,  5,  2, 12 ]
 35 #S盒中的S4盒
 36 S4=[ 7, 13, 14,  3,  0,  6,  9, 10,  1,  2,  8,  5, 11, 12,  4, 15,
 37     13,  8, 11,  5,  6, 15,  0,  3,  4,  7,  2, 12,  1, 10, 14,  9,
 38     10,  6,  9,  0, 12, 11,  7, 13, 15,  1,  3, 14,  5,  2,  8,  4,
 39      3, 15,  0,  6, 10,  1, 13,  8,  9,  4,  5, 11, 12,  7,  2, 14 ]
 40 #S盒中的S5盒
 41 S5=[ 2, 12,  4,  1,  7, 10, 11,  6,  8,  5,  3, 15, 13,  0, 14,  9,
 42     14, 11,  2, 12,  4,  7, 13,  1,  5,  0, 15, 10,  3,  9,  8,  6,
 43      4,  2,  1, 11, 10, 13,  7,  8, 15,  9, 12,  5,  6,  3,  0, 14,
 44     11,  8, 12,  7,  1, 14,  2, 13,  6, 15,  0,  9, 10,  4,  5,  3 ]
 45 #S盒中的S6盒
 46 S6=[12,  1, 10, 15,  9,  2,  6,  8,  0, 13,  3,  4, 14,  7,  5, 11,
 47     10, 15,  4,  2,  7, 12,  9,  5,  6,  1, 13, 14,  0, 11,  3,  8,
 48      9, 14, 15,  5,  2,  8, 12,  3,  7,  0,  4, 10,  1, 13, 11,  6,
 49      4,  3,  2, 12,  9,  5, 15, 10, 11, 14,  1,  7,  6,  0,  8, 13 ]
 50 #S盒中的S7盒
 51 S7=[ 4, 11,  2, 14, 15,  0,  8, 13,  3, 12,  9,  7,  5, 10,  6,  1,
 52     13,  0, 11,  7,  4,  9,  1, 10, 14,  3,  5, 12,  2, 15,  8,  6,
 53      1,  4, 11, 13, 12,  3,  7, 14, 10, 15,  6,  8,  0,  5,  9,  2,
 54      6, 11, 13,  8,  1,  4, 10,  7,  9,  5,  0, 15, 14,  2,  3, 12]
 55 #S盒中的S8盒
 56 S8=[13,  2,  8,  4,  6, 15, 11,  1, 10,  9,  3, 14,  5,  0, 12,  7,
 57      1, 15, 13,  8, 10,  3,  7,  4, 12,  5,  6, 11,  0, 14,  9,  2,
 58      7, 11,  4,  1,  9, 12, 14,  2,  0,  6, 10, 13, 15,  3,  5,  8,
 59      2,  1, 14,  7,  4, 10,  8, 13, 15, 12,  9,  0,  3,  5,  6, 11 ]
 60 # S盒
 61 S=[S1,S2,S3,S4,S5,S6,S7,S8]
 62 #用于对数据进行扩展置换，将32bit数据扩展为48bit
 63 extend_table=[32,  1,  2,  3,  4,  5,
 64                4,  5,  6,  7,  8,  9,
 65                8,  9, 10, 11, 12, 13,
 66               12, 13, 14, 15, 16, 17,
 67               16, 17, 18, 19, 20, 21,
 68               20, 21, 22, 23, 24, 25,
 69               24, 25, 26, 27, 28, 29,
 70               28, 29, 30, 31, 32,  1 ]
 71 #P盒
 72 P_table=[ 16,  7, 20, 21, 29, 12, 28, 17,
 73            1, 15, 23, 26,  5, 18, 31, 10,
 74            2,  8, 24, 14, 32, 27,  3,  9,
 75           19, 13, 30,  6, 22, 11,  4, 25 ]
 76 
 77 def int2bit(n):#0~15整数转比特
 78     a=[]
 79     for i in range(0,4):
 80         a.insert(0,str(n%2))
 81         n=int(n/2)
 82     return a
 83 
 84 #IP置换部分，op为0表示正置换，op为1表示逆置换
 85 def IP(text, op):   
 86     tmp = [0 for i in range(64)]
 87     if op == 0:
 88         for i in range(64):
 89             tmp[i] = text[IP_table[i]-1]
 90         return tmp
 91     if op == 1:
 92         for i in range(64):
 93             tmp[i] = text[Inv_IP_table[i]-1]
 94         return tmp
 95 #进行扩展，将32位扩展为48位
 96 def Extend(text):
 97     extend = [0 for i in range(48)]
 98     for i in range(48):
 99         extend[i] = text[extend_table[i] - 1]
100     return extend
101 
102 #S盒变换部分
103 def S_replace(text):
104     Sresult = [0 for k in range(32)]
105     for k in range(8):
106         row = 2*int(text[k*6]) + int(text[k*6+5])
107         column = 8*int(text[k*6+1]) + 4*int(text[k*6+2]) + 2*int(text[k*6+3]) + int(text[k*6+4])
108         tmp = S[k][row*16+column]
109 
110         for i in range(4):
111             Sresult[4*k + i] = int2bit(tmp)[i]
112     return Sresult
113 #P置换部分
114 def P_replace(text):
115     Presult = [0 for i in range(32)]
116     for i in range(32):
117         Presult[i] = text[P_table[i]-1]
118     return Presult
119 #异或运算
120 def Xor(bit1, bit2):
121     Xorresult = [0 for i in range(len(bit1))]
122     for i in range(len(bit1)):
123         Xorresult[i] = str(int(bit1[i]) ^ int(bit2[i]))
124     return Xorresult

DES加密模块：

 1 import CreateSubkey as cs
 2 import F_function as f
 3 #十六进制转二进制比特串
 4 def Hex2bin(text):
 5     result = []
 6     for i in range(len(text)):
 7         result.extend(f.int2bit(int(text[i],16)))
 8     return result
 9 #二进制比特串转十六进制
10 def bin2Hex(text):
11     result = []
12     q = len(text)//4
13     for i in range(q):
14         dec = int(text[4*i])*8 + int(text[4*i+1])*4 + int(text[4*i+2])*2 + int(text[4*i+3])*1
15         x = hex(dec)[2:].upper()
16         result.extend(x)
17     rs = ''.join(result)
18     return rs
19 #按照DES算法的流程图进行运算
20 def Encryption(text, key):
21     keylist = cs.Subkey(keybit)
22     text1 = f.IP(text, 0)  #IP置换
23     L = [text1[i] for i in range(32)]
24     R = [text1[i] for i in range(32,64)]
25     for i in range(16):
26         tmp = R
27         tmp = f.Extend(tmp)
28         tmp = f.Xor(tmp, keylist[i])
29         tmp = f.S_replace(tmp)
30         tmp = f.P_replace(tmp)
31         tmp = f.Xor(tmp, L)
32         L = R
33         R = tmp
34     L,R = R,L
35     ctext = L
36     ctext.extend(R)
37     ctext = f.IP(ctext, 1)
38     return bin2Hex(ctext)
39 
40 if __name__ == '__main__':
41     plaintext = input('请输入用十六进制表示的明文：') 
42     key = input('请输入用十六进制表示的密钥：')
43     ptext = Hex2bin(plaintext)
44     keybit = Hex2bin(key)
45     print('输出的密文为：' + Encryption(ptext, keybit))

DES解密模块：

 1 import CreateSubkey as cs
 2 import F_function as f
 3 #十六进制转二进制比特串
 4 def Hex2bin(text):
 5     result = []
 6     for i in range(len(text)):
 7         result.extend(f.int2bit(int(text[i],16)))
 8     return result
 9 #二进制比特串转十六进制
10 def bin2Hex(text):
11     result = []
12     q = len(text)//4
13     for i in range(q):
14         dec = int(text[4*i])*8 + int(text[4*i+1])*4 + int(text[4*i+2])*2 + int(text[4*i+3])*1
15         x = hex(dec)[2:].upper()
16         result.extend(x)
17     rs = ''.join(result)
18     return rs
19 
20 def Encryption(text, key):
21     keylist = cs.Subkey(keybit)
22     text1 = f.IP(text, 0)  #IP置换
23     L = [text1[i] for i in range(32)]
24     R = [text1[i] for i in range(32,64)]
25     for i in range(16):
26         tmp = R
27         tmp = f.Extend(tmp)
28         tmp = f.Xor(tmp, keylist[15-i])
29         tmp = f.S_replace(tmp)
30         tmp = f.P_replace(tmp)
31         tmp = f.Xor(tmp, L)
32         L = R
33         R = tmp
34     L,R = R,L
35     ctext = L
36     ctext.extend(R)
37     ctext = f.IP(ctext, 1)
38     return bin2Hex(ctext)
39 
40 if __name__ == '__main__':
41     plaintext = input('请输入用十六进制表示的密文：') 
42     key = input('请输入用十六进制表示的密钥：')
43     ptext = Hex2bin(plaintext)
44     keybit = Hex2bin(key)
45     print('输出的明文为：' + Encryption(ptext, keybit))