数据加密标准DES加密算法是一种对称加密算法，DES 使用一个 56 位的密钥以及附加的 8 位奇偶校验位，产生最大 64 位的分组大小。这是一个迭代的分组密码，使用称为 Feistel 的技术，其中将加密的文本块分成两半。使用子密钥对其中一半应用循环功能，然后将输出与另一半进行“异或”运算；接着交换这两半，这一过程会继续下去，但最后一个循环不交换。DES 使用 16 个循环，使用异或，置换，代换，移位操作四种基本运算。

 下面是我自己用C语言实现的DES加密代码,如有错误，欢迎指正！

1 #include
     
        2 #include
      
         3 #include
       
          4   5 //IP初始置换表  6 int IP_Table[64]={               7     58,50,42,34,26,18,10, 2,60,52,44,36,28,20,12, 4,  8     62,54,46,38,30,22,14, 6,64,56,48,40,32,24,16, 8,  9     57,49,41,33,25,17, 9, 1,59,51,43,35,27,19,11, 3, 10     61,53,45,37,29,21,13, 5,63,55,47,39,31,23,15, 7  11 }; 12  13 //IP逆置换表 14 int IPR_Table[64] = { 15         40,8,48,16,56,24,64,32,39,7,47,15,55,23,63,31, 16         38,6,46,14,54,22,62,30,37,5,45,13,53,21,61,29, 17         36,4,44,12,52,20,60,28,35,3,43,11,51,19,59,27, 18         34,2,42,10,50,18,58,26,33,1,41,9,49,17,57,25 19 }; 20  21 //E位选择表(扩展置换表) 22 int E_Table[48] = { 23         32,1,2,3,4,5,4,5,6,7,8,9, 24         8,9,10,11,12,13,12,13,14,15,16,17, 25         16,17,18,19,20,21,20,21,22,23,24,25, 26         24,25,26,27,28,29,28,29,30,31,32,1 27 }; 28 int P_Table[32] = { 29         16,7,20,21,29,12,28,17,1,15,23,26,5,18,31,10, 30         2,8,24,14,32,27,3,9,19,13,30,6,22,11,4,25 31 }; 32  33 int PC1_Table[56] = { 34         57,49,41,33,25,17,9,1,58,50,42,34,26,18, 35         10,2,59,51,43,35,27,19,11,3,60,52,44,36, 36         63,55,47,39,31,23,15,7,62,54,46,38,30,22, 37         14,6,61,53,45,37,29,21,13,5,28,20,12,4 38 }; 39 //PC2选位表(密钥生成置换表2) 40 int PC2_Table[48] = { 41         14,17,11,24,1,5,3,28,15,6,21,10, 42         23,19,12,4,26,8,16,7,27,20,13,2, 43         41,52,31,37,47,55,30,40,51,45,33,48, 44         44,49,39,56,34,53,46,42,50,36,29,32 45 }; 46 //左移位数表  47  int LOOP_Table[16] = { 48     1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1 49 }; 50 // S盒 51  int S_Box[8][4][16] = { 52         // S1  53         14,4,13,1,2,15,11,8,3,10,6,12,5,9,0,7, 54         0,15,7,4,14,2,13,1,10,6,12,11,9,5,3,8, 55         4,1,14,8,13,6,2,11,15,12,9,7,3,10,5,0, 56         15,12,8,2,4,9,1,7,5,11,3,14,10,0,6,13, 57         //S2 58         15,1,8,14,6,11,3,4,9,7,2,13,12,0,5,10, 59         3,13,4,7,15,2,8,14,12,0,1,10,6,9,11,5, 60         0,14,7,11,10,4,13,1,5,8,12,6,9,3,2,15, 61         13,8,10,1,3,15,4,2,11,6,7,12,0,5,14,9, 62         //S3 63         10,0,9,14,6,3,15,5,1,13,12,7,11,4,2,8, 64         13,7,0,9,3,4,6,10,2,8,5,14,12,11,15,1, 65         13,6,4,9,8,15,3,0,11,1,2,12,5,10,14,7, 66         1,10,13,0,6,9,8,7,4,15,14,3,11,5,2,12, 67         //S4 68         7,13,14,3,0,6,9,10,1,2,8,5,11,12,4,15, 69         13,8,11,5,6,15,0,3,4,7,2,12,1,10,14,9, 70         10,6,9,0,12,11,7,13,15,1,3,14,5,2,8,4, 71         3,15,0,6,10,1,13,8,9,4,5,11,12,7,2,14, 72         //S5 73         2,12,4,1,7,10,11,6,8,5,3,15,13,0,14,9, 74         14,11,2,12,4,7,13,1,5,0,15,10,3,9,8,6, 75         4,2,1,11,10,13,7,8,15,9,12,5,6,3,0,14, 76         11,8,12,7,1,14,2,13,6,15,0,9,10,4,5,3, 77         //S6 78         12,1,10,15,9,2,6,8,0,13,3,4,14,7,5,11, 79         10,15,4,2,7,12,9,5,6,1,13,14,0,11,3,8, 80         9,14,15,5,2,8,12,3,7,0,4,10,1,13,11,6, 81         4,3,2,12,9,5,15,10,11,14,1,7,6,0,8,13, 82         //S7 83         4,11,2,14,15,0,8,13,3,12,9,7,5,10,6,1, 84         13,0,11,7,4,9,1,10,14,3,5,12,2,15,8,6, 85         1,4,11,13,12,3,7,14,10,15,6,8,0,5,9,2, 86         6,11,13,8,1,4,10,7,9,5,0,15,14,2,3,12, 87         //S8 88         13,2,8,4,6,15,11,1,10,9,3,14,5,0,12,7, 89         1,15,13,8,10,3,7,4,12,5,6,11,0,14,9,2, 90         7,11,4,1,9,12,14,2,0,6,10,13,15,3,5,8, 91         2,1,14,7,4,10,8,13,15,12,9,0,3,5,6,11 92 }; 93 void ShowArray(int *array,int num); 94 void BitsCopy(int *DatOut,int *DatIn,int Len); 95 //将字符数组转换成二进制数组 96 void CharToBit(char *input,int *output,int bits) 97 { 98     int i=0; 99     for(i=0;i
        
         >(i%8))&1; 102     }103 }104 105 //将二进制数组转换成字符数组106 void BitToChar(int *input, char *output, int bits)107 {108     int i=0;109     for(i=0;i<(bits/8);i++)110     {111         output[i]=0;112     }113     for(i=0;i
         
          9)271         {272             DatOut[i]=DatOut[i]%16+'7';       //  余数大于9时处理 10-15 to A-F273         }                                     //  输出字符 274         else275         {276             DatOut[i]=DatOut[i]%16+'0';       //  输出字符       277         }278     }279     280 }281 282 //DES加密283 void  DES_Dfun(int input[],char key_in[],char output[])284 {285     int ML[32]={
   0},MR[32]={
   0};286     int temp1[64],temp2[32],temp3[64];287     int Subkey[16][48];288     int input_l[32]={
   0};289     int input_r[32]={
   0};290     int testi=0;291     for(testi=0;testi<32;testi++)292     {293         input_l[testi]=input[testi];294     }295     for(testi=0;testi<32;testi++)296     {297         input_r[testi]=input[32+testi];298     }299     BitsCopy(ML,input_l,32);300     BitsCopy(MR,input_r,32);301     BitsCopy(temp1,input,64);302     IP_IPR(temp1,input,IP_Table); //IP置换303     printf("IP初始置换：\n");304     ShowArray(input,64);305     CharToBit(key_in,temp3,64);306     subKey_fun(temp3,Subkey);   //子秘钥的生成307     for(int i=0;i<16;i++)                       // 迭代16次 308     {309         printf("***第%d轮迭代:***\n",i+1); 310         BitsCopy(temp2,MR,32);            // 临时存储311         F_func(MR,Subkey[i]);           // F函数变换312         Xor(MR,ML,32);             // 得到Ri 313         BitsCopy(ML,temp2,32);            // 得到Li 314         printf("ML:\n");315         ShowArray(ML,32);316         printf("MR:\n");317         ShowArray(MR,32);318     }    319     IP_IPR(input,temp1,IPR_Table);320     BitToHex(output,input,64);321 }322 323  //输出字符数组324 void ShowArray(int *array,int num)325 {326     int i;327     for(i=0;i