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))