DES算法的C语言实现

LegendSaber

       曾经学习DES算法时候写过的一份C语言实现的DES加解密算法。现在提供给大家参考
       首先，由于DES是在比特层面对输入进行加密的。所以，首先需要做到将输入的字符与其二进制形式的互相转换，这部分代码在CChar中实现

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#include "CChar.h"   void CharToBit(char input[], char output[]) {         int i = 0, j = 0, k = 0;                   for (i = 0; i < 8; i++)         {                 for (j = 0; j < 8; j++)                 {                         k = 7 - j;                         output[i * 8 + j] = (input[i] >> k) & 0x1;                 }         } }   void BitToChar(char input[], char output[]) {         int i = 0, j = 0, k = 0;           for (i = 0; i < 8; i++)         {                 for (j = 0; j < 8; j++)                 {                         k = 7 - j;                         output[i] |= (input[i * 8 + j] << k);                 }         } }

         其次，为了完成DES加密需要用到的密钥以及置换表等等这部分内容在table.h中定义

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#ifndef __MY_TABLE_ #define __MY_TABLE_   //存储程序所需要的表与密钥   //初始置换表IP const char IP_Table[64] = { 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};   //逆初始置换表IP^-1  const char IP_1_Table[64] = { 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}; //扩展表E const char E_Table[48] = { 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}; //置换表P const char P_Table[32] = { 15, 6, 19, 20, 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盒 const char S[8][4][16] =                 {                     //S1                     {{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}},                      //S2                      {{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}},                     //S3                      {{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}},                      //S4                      {{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}},                      //S5                      {{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}},                      //S6                      {{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}},                      //S7                      {{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}},                      //S8                      {{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}}                 };   //置换选择1         int PC_1[56] = { 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,                   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};      //置换选择2  int PC_2[48] = { 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,                   50,44,32,46,43,48,38,55,                   33,52,45,41,49,35,28,31};                   //循环左移的位数 const char RoundLeft[16] = {1, 1, 2, 2,                             2, 2, 2, 2,                             1, 2, 2, 2,                             2, 2, 1, 1}; //加密密钥                      const char cKey[9] = {"12345678"}; char bKey[56] = { 0 }; //IV向量 char cIV[9] = {"IVVector"}; #endif

         最后就是在主函数中对输入进行16轮的DES加密

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#include <cstdio> #include <cstring> #include "table.h" #include "CChar.h"   void DESAlgorithm(char cOrigData[]);        //DES算法主体 //对左边32比特进行加密 void XOREncryptLeft(char cLeftChar[], char cRightChar[], int iIndex); void InitBitKey();        //将密钥初始化为比特形式且进行置换        void EncryptByCBC(char cOrigData[], char cOrigData2[]);        //采用CBC模式加密 void EncryptByCFB(char cOrigData[], char cOrigData2[]); //采用CFB模式加密   int main() {         char cOrigData[9] = {"1900Code"};         char cOrigData2[9] = {"I 1900"};                   printf("加密前的数据: %s %s\n", cOrigData, cOrigData2);                   EncryptByCBC(cOrigData, cOrigData2);         EncryptByCFB(cOrigData, cOrigData2);                   getchar();         return 0; }   void EncryptByCFB(char cOrigData[], char cOrigData2[]) {         InitBitKey();         DESAlgorithm(cIV);                   for (int i = 0; i < 9; i++) cOrigData[i] ^= cIV[i];         printf("CFB模式加密后的数据:%s ", cOrigData);                   InitBitKey();         DESAlgorithm(cOrigData);                   for (int i = 0; i < 9; i++) cOrigData2[i] ^= cOrigData[i];         printf("%s\n", cOrigData2);                             for (int i = 0; i < 9; i++) cOrigData2[i] ^= cOrigData[i];         InitBitKey();         DESAlgorithm(cOrigData);         for (int i = 0; i < 9; i++) cOrigData[i] ^= cIV[i];         printf("CFB模式解密的数据:%s %s\n", cOrigData, cOrigData2);         InitBitKey();         DESAlgorithm(cIV); }   void EncryptByCBC(char cOrigData[], char cOrigData2[]) {         InitBitKey();         for (int i = 0; i < 9; i++) cOrigData[i] ^= cIV[i];         DESAlgorithm(cOrigData);           InitBitKey();         for (int i = 0; i < 9; i++) cOrigData2[i] ^= cOrigData[i];         DESAlgorithm(cOrigData2);         printf("CBC模式加密后结果: %s %s\n", cOrigData, cOrigData2);                   InitBitKey();         DESAlgorithm(cOrigData2);         for (int i = 0; i < 9; i++) cOrigData2[i] ^= cOrigData[i];                   InitBitKey();         DESAlgorithm(cOrigData);         for (int i = 0; i < 9; i++) cOrigData[i] ^= cIV[i];         printf("CBC模式解密后的数据: %s %s\n", cOrigData, cOrigData2); }   void DESAlgorithm(char cOrigData[]) {         char cLeft[32] = { 0 }, cRight[32] = { 0 }, cOrigChar[64] = { 0 };         char cTmp = 0, cOrigCpyChar[64] = { 0 };           CharToBit(cOrigData, cOrigChar);                   memset(cOrigCpyChar, 0, sizeof(cOrigCpyChar));         memcpy(cOrigCpyChar, cOrigChar, 64);        //进行初始置换         for (int i = 0; i < 64; i++)         {                 cOrigChar[i] = cOrigCpyChar[IP_Table[i]];         }                   for (int i = 0; i < 32; i++)         {                 cLeft[i] = cOrigChar[i];                 cRight[i] = cOrigChar[32 + i];         }                   for (int i = 0; i < 16; i++)        //进行16轮的加密         {                 XOREncryptLeft(cLeft, cRight, i);                                   //除最后一轮，交换左右两边的比特                 if (i < 15)                 {                         for (int j = 0; j < 32; j++)                         {                                 cTmp = cLeft[j];                                 cLeft[j] = cRight[j];                                 cRight[j] = cTmp;                         }                 }         }                   for (int i = 0; i < 32; i++)         {                 cOrigChar[i] = cLeft[i];                 cOrigChar[32 + i] = cRight[i];         }           memset(cOrigCpyChar, 0, sizeof(cOrigCpyChar));         memcpy(cOrigCpyChar, cOrigChar, 64);        //进行逆初始置换         for (int i = 0; i < 64; i++)         {                 cOrigChar[i] = cOrigCpyChar[IP_1_Table[i]];         }                   memset(cOrigData, 0, sizeof(cOrigData));         BitToChar(cOrigChar, cOrigData); }   void XOREncryptLeft(char cLeftChar[], char cRightChar[], int iIndex) {         char cExtendChar[48] = { 0 };         int i = 0, moveNum = 0, col = 0, row = 0, j = 0, k = 0, l = 0;         char cLeftKey[28] = { 0 }, cRightKey[28] = { 0 };         char bEncryptKey[48] = { 0 };         char bSData[32] = { 0 };         char cSData = 0;                   //进行扩展E置换         for (i = 0; i < 48; i++)         {                 cExtendChar[i] = cRightChar[E_Table[i]];         }                   for (i = 0; i < 28; i++)         {                 cLeftKey[i] = bKey[i];                 cRightKey[i] = bKey[28 + i];         }                   moveNum = RoundLeft[iIndex];         for (i = 0; i < 28 - moveNum; i++)         {                 cLeftKey[i] = cLeftKey[i + moveNum];                 cRightKey[i] = cRightKey[i + moveNum];         }                   for (i = 28 - moveNum; i < 28; i++)         {                 cLeftKey[i] = 0;                 cRightKey[i] = 0;         }                   for (i = 0; i < 28; i++)         {                 bKey[i] = cLeftKey[i];                 bKey[28 + i] = cRightKey[i];         }                   for (i = 0; i < 48; i++) bEncryptKey[i] = bKey[PC_2[i]];                   for (i = 0; i < 48; i++) cExtendChar[i] |= bEncryptKey[i];                   for (i = 0; i < 8; i++)         {                 row = (cExtendChar[i * 8] - '0') * 2 + (cExtendChar[i * 8 + 5] - '0');                 col = (cExtendChar[i * 8 + 1] - '0') * 8 + (cExtendChar[i * 8 + 2] - '0') * 4                         + (cExtendChar[i * 8 + 3] - '0') * 2 + (cExtendChar[i * 8 + 4] - '0');                                           cSData = S[iIndex][row][col];                 if (cSData >= 8)                 {                         bSData[i * 4] = 1;                         cSData -= 8;                 }                                   if (cSData >= 4)                 {                         bSData[i * 4 + 1] = 1;                         cSData -= 4;                 }                                   if (cSData >= 2)                 {                         bSData[i * 4 + 2] = 1;                         cSData -= 2;                 }                                   if (cSData == 1) bSData[i * 4 + 3] = 1;         }                   for (i = 0; i < 32; i++) cLeftChar[i] |= bSData[i]; }   void InitBitKey() {         int i = 0, j = 0, k = 0;         char bCpyKey[56] = { 0 };                   for (i = 0; i < 7; i++)         {                 for (j = 0; j < 8; j++)                 {                         k = 7 - j;                         bKey[i * 8 + j] = (cKey[i] >> k) & 0x1;                 }         }                   memset(bCpyKey, 0, sizeof(bCpyKey));         memcpy(bCpyKey, bKey, 56);         for (i = 0; i < 56; i++)         {                 bKey[i] = bCpyKey[PC_1[i]];         } }

          可以看到最终的输出，程序成功对输入的字符进行DES的加密解密

LegendSaber

Eaglecad 发表于 2021-10-24 12:51
感谢分享，要是再讲解下原理啥的更好

哦。。那是因为这种经典的密码算法原理网上真的特别特别多。。再写的话挺多余的。。。。

LegendSaber

nanaqilin 发表于 2021-10-24 13:07
我早就不是学生了，我是社会人事，现在做项目都是用openssl

实际项目肯定是调包啊。。。谁能写的比那些人好啊。。。

Eaglecad

感谢分享，要是再讲解下原理啥的更好

nanaqilin

你这个挺厉害的，我都是用openssl来实现加解密

LegendSaber

nanaqilin 发表于 2021-10-24 12:58
你这个挺厉害的，我都是用openssl来实现加解密

谁还不是被挂科的恐惧逼了一把。。。

nanaqilin

LegendSaber 发表于 2021-10-24 13:00
谁还不是被挂科的恐惧逼了一把。。。

我早就不是学生了，我是社会人事，现在做项目都是用openssl

大脑组织残缺

DES，RSA 网络安全课上做过

yacc

LegendSaber 发表于 2021-10-24 13:00
谁还不是被挂科的恐惧逼了一把。。。

当年被密码学考试支配的恐惧

谁的坏叔叔

有易语言的吗