DES加密算法-C语言

头文件：DES.h

 #ifndef DES_hpp
 #define DES_hpp

 #include <stdio.h>
 #include <memory.h>
 #include <time.h>
 #include <stdlib.h>

 #define PLAIN_FILE_OPEN_ERROR -1
 #define KEY_FILE_OPEN_ERROR -2
 #define CIPHER_FILE_OPEN_ERROR -3
 #define OK 1

 typedef char ElemType;

 int ByteToBit(ElemType ch,ElemType bit[]);
 int BitToByte(ElemType bit[],ElemType *ch);
 int Char8ToBit64(ElemType ch[],ElemType bit[]);
 int Bit64ToChar8(ElemType bit[],ElemType ch[]);
 int DES_MakeSubKeys(ElemType key[],ElemType subKeys[][]);
 int DES_PC1_Transform(ElemType key[], ElemType tempbts[]);
 int DES_PC2_Transform(ElemType key[], ElemType tempbts[]);
 int DES_ROL(ElemType data[], int time);
 int DES_IP_Transform(ElemType data[]);
 int DES_IP_1_Transform(ElemType data[]);
 int DES_E_Transform(ElemType data[]);
 int DES_P_Transform(ElemType data[]);
 int DES_SBOX(ElemType data[]);
 int DES_XOR(ElemType R[], ElemType L[],int count);
 int DES_Swap(ElemType left[],ElemType right[]);
 int DES_EncryptBlock(ElemType plainBlock[], ElemType subKeys[][], ElemType cipherBlock[]);
 int DES_DecryptBlock(ElemType cipherBlock[], ElemType subKeys[][], ElemType plainBlock[]);
 int DES_Encrypt(char *plainFile, char *keyStr,char *cipherFile);
 int DES_Decrypt(char *cipherFile, char *keyStr,char *plainFile);

 #endif /* DES_hpp */

C代码：DES.cpp

 #include "DES.h"

 //初始置换表IP
 int IP_Table[] = {  ,,,,,,,,
     ,,,,,,,,
     ,,,,,,,,
     ,,,,,,,,
     ,,,,,,,,
     ,,,,,,,,
     ,,,,,,,,
     ,,,,,,,};
 //逆初始置换表IP^-1
 int IP_1_Table[] = {,,,,,,,,
     ,,,,,,,,
     ,,,,,,,,
     ,,,,,,,,
     ,,,,,,,,
     ,,,,,,,,
     ,,,,,,,,
     ,,,,,,,};

 //扩充置换表E
 int E_Table[] = {, , , , , ,
     ,  , , , , ,
     ,  ,,,,,
     ,,,,,,
     ,,,,,,
     ,,,,,,
     ,,,,,,
     ,,,,, };

 //置换函数P
 int P_Table[] = {,,,,,,,,
     ,,,,,,,,
     ,,,,,,,,
     ,,,,,,,};

 //S盒
 int S[][][] =//S1
 {{{,,,,,,,,,,,,,,,},
     {,,,,,,,,,,,,,,,},
     {,,,,,,,,,,,,,,,},
     {,,,,,,,,,,,,,,,}},
     //S2
     {{,,,,,,,,,,,,,,,},
         {,,,,,,,,,,,,,,,},
         {,,,,,,,,,,,,,,,},
         {,,,,,,,,,,,,,,,}},
     //S3
     {{,,,,,,,,,,,,,,,},
         {,,,,,,,,,,,,,,,},
         {,,,,,,,,,,,,,,,},
         {,,,,,,,,,,,,,,,}},
     //S4
     {{,,,,,,,,,,,,,,,},
         {,,,,,,,,,,,,,,,},
         {,,,,,,,,,,,,,,,},
         {,,,,,,,,,,,,,,,}},
     //S5
     {{,,,,,,,,,,,,,,,},
         {,,,,,,,,,,,,,,,},
         {,,,,,,,,,,,,,,,},
         {,,,,,,,,,,,,,,,}},
     //S6
     {{,,,,,,,,,,,,,,,},
         {,,,,,,,,,,,,,,,},
         {,,,,,,,,,,,,,,,},
         {,,,,,,,,,,,,,,,}},
     //S7
     {{,,,,,,,,,,,,,,,},
         {,,,,,,,,,,,,,,,},
         {,,,,,,,,,,,,,,,},
         {,,,,,,,,,,,,,,,}},
     //S8
     {{,,,,,,,,,,,,,,,},
         {,,,,,,,,,,,,,,,},
         {,,,,,,,,,,,,,,,},
         {,,,,,,,,,,,,,,,}}};
 //置换选择1
 int PC_1[] = {,,,,,,,
     ,,,,,,,
     ,,,,,,,
     ,,,,,,,
     ,,,,,,,
     ,,,,,,,
     ,,,,,,,
     ,,,,,,};

 //置换选择2
 int PC_2[] = {,,,,,,,,
     ,,,,,,,,
     ,,,,,,,,
     ,,,,,,,,
     ,,,,,,,,
     ,,,,,,,};

 //对左移次数的规定
 int MOVE_TIMES[] = {,,,,,,,,,,,,,,,};

 //字节转换成二进制
 int ByteToBit(ElemType ch, ElemType bit[]){
     int cnt;
     for(cnt = ;cnt < ; cnt++){
         *(bit+cnt) = (ch>>cnt)&;
     }
     return ;
 }

 //二进制转换成字节
 int BitToByte(ElemType bit[],ElemType *ch){
     int cnt;
     for(cnt = ;cnt < ; cnt++){
         *ch |= *(bit + cnt)<<cnt;
     }
     return ;
 }

 //将长度为8的字符串转为二进制位串
 int Char8ToBit64(ElemType ch[],ElemType bit[]){
     int cnt;
     for(cnt = ; cnt < ; cnt++){
         ByteToBit(*(ch+cnt),bit+(cnt<<));
     }
     return ;
 }

 //将二进制位串转为长度为8的字符串
 int Bit64ToChar8(ElemType bit[],ElemType ch[]){
     int cnt;
     memset(ch,,);
     for(cnt = ; cnt < ; cnt++){
         BitToByte(bit+(cnt<<),ch+cnt);
     }
     return ;
 }

 //生成子密钥
 int DES_MakeSubKeys(ElemType key[],ElemType subKeys[][]){
     ElemType temp[];
     int cnt;
     DES_PC1_Transform(key,temp);//PC1置换
     for(cnt = ; cnt < ; cnt++){//16轮跌代，产生16个子密钥
         DES_ROL(temp,MOVE_TIMES[cnt]);//循环左移
         DES_PC2_Transform(temp,subKeys[cnt]);//PC2置换，产生子密钥
     }
     return ;
 }

 //密钥置换1
 int DES_PC1_Transform(ElemType key[], ElemType tempbts[]){
     int cnt;
     for(cnt = ; cnt < ; cnt++){
         tempbts[cnt] = key[PC_1[cnt]];
     }
     return ;
 }

 //密钥置换2
 int DES_PC2_Transform(ElemType key[], ElemType tempbts[]){
     int cnt;
     for(cnt = ; cnt < ; cnt++){
         tempbts[cnt] = key[PC_2[cnt]];
     }
     return ;
 }

 //循环左移
 int DES_ROL(ElemType data[], int time){
     ElemType temp[];

     //保存将要循环移动到右边的位
     memcpy(temp,data,time);
     memcpy(temp+time,data+,time);

     //前28位移动
     memcpy(data,data+time,-time);
     memcpy(data+-time,temp,time);

     //后28位移动
     memcpy(data+,data++time,-time);
     memcpy(data+-time,temp+time,time);

     return ;
 }

 //IP置换
 int DES_IP_Transform(ElemType data[]){
     int cnt;
     ElemType temp[];
     for(cnt = ; cnt < ; cnt++){
         temp[cnt] = data[IP_Table[cnt]];
     }
     memcpy(data,temp,);
     return ;
 }

 //IP逆置换
 int DES_IP_1_Transform(ElemType data[]){
     int cnt;
     ElemType temp[];
     for(cnt = ; cnt < ; cnt++){
         temp[cnt] = data[IP_1_Table[cnt]];
     }
     memcpy(data,temp,);
     return ;
 }

 //扩展置换
 int DES_E_Transform(ElemType data[]){
     int cnt;
     ElemType temp[];
     for(cnt = ; cnt < ; cnt++){
         temp[cnt] = data[E_Table[cnt]];
     }
     memcpy(data,temp,);
     return ;
 }

 //P置换
 int DES_P_Transform(ElemType data[]){
     int cnt;
     ElemType temp[];
     for(cnt = ; cnt < ; cnt++){
         temp[cnt] = data[P_Table[cnt]];
     }
     memcpy(data,temp,);
     return ;
 }

 //异或
 int DES_XOR(ElemType R[], ElemType L[] ,int count){
     int cnt;
     for(cnt = ; cnt < count; cnt++){
         R[cnt] ^= L[cnt];
     }
     return ;
 }

 //S盒置换
 int DES_SBOX(ElemType data[]){
     int cnt;
     int line,row,output;
     int cur1,cur2;
     for(cnt = ; cnt < ; cnt++){
         cur1 = cnt*;
         cur2 = cnt<<;

         //计算在S盒中的行与列
         line = (data[cur1]<<) + data[cur1+];
         row = (data[cur1+]<<) + (data[cur1+]<<)
         + (data[cur1+]<<) + data[cur1+];
         output = S[cnt][line][row];

         //化为2进制
         data[cur2] = (output&0X08)>>;
         data[cur2+] = (output&0X04)>>;
         data[cur2+] = (output&0X02)>>;
         data[cur2+] = output&0x01;
     }
     return ;
 }

 //交换
 int DES_Swap(ElemType left[], ElemType right[]){
     ElemType temp[];
     memcpy(temp,left,);
     memcpy(left,right,);
     memcpy(right,temp,);
     return ;
 }

 //加密单个分组
 int DES_EncryptBlock(ElemType plainBlock[], ElemType subKeys[][], ElemType cipherBlock[]){
     ElemType plainBits[];
     ElemType copyRight[];
     int cnt;

     Char8ToBit64(plainBlock,plainBits);
     //初始置换（IP置换）
     DES_IP_Transform(plainBits);

     //16轮迭代
     for(cnt = ; cnt < ; cnt++){
         memcpy(copyRight,plainBits+,);
         //将右半部分进行扩展置换，从32位扩展到48位
         DES_E_Transform(copyRight);
         //将右半部分与子密钥进行异或操作
         DES_XOR(copyRight,subKeys[cnt],);
         //异或结果进入S盒，输出32位结果
         DES_SBOX(copyRight);
         //P置换
         DES_P_Transform(copyRight);
         //将明文左半部分与右半部分进行异或
         DES_XOR(plainBits,copyRight,);
         if(cnt != ){
             //最终完成左右部的交换
             DES_Swap(plainBits,plainBits+);
         }
     }
     //逆初始置换（IP^1置换）
     DES_IP_1_Transform(plainBits);
     Bit64ToChar8(plainBits,cipherBlock);
     return ;
 }

 //解密单个分组
 int DES_DecryptBlock(ElemType cipherBlock[], ElemType subKeys[][],ElemType plainBlock[]){
     ElemType cipherBits[];
     ElemType copyRight[];
     int cnt;

     Char8ToBit64(cipherBlock,cipherBits);
     //初始置换（IP置换）
     DES_IP_Transform(cipherBits);

     //16轮迭代
     for(cnt = ; cnt >= ; cnt--){
         memcpy(copyRight,cipherBits+,);
         //将右半部分进行扩展置换，从32位扩展到48位
         DES_E_Transform(copyRight);
         //将右半部分与子密钥进行异或操作
         DES_XOR(copyRight,subKeys[cnt],);
         //异或结果进入S盒，输出32位结果
         DES_SBOX(copyRight);
         //P置换
         DES_P_Transform(copyRight);
         //将明文左半部分与右半部分进行异或
         DES_XOR(cipherBits,copyRight,);
         if(cnt != ){
             //最终完成左右部的交换
             DES_Swap(cipherBits,cipherBits+);
         }
     }
     //逆初始置换（IP^1置换）
     DES_IP_1_Transform(cipherBits);
     Bit64ToChar8(cipherBits,plainBlock);
     return ;
 }

 //加密文件
 int DES_Encrypt(char *plainFile, char *keyStr,char *cipherFile){
     FILE *plain,*cipher;
     int count;
     ElemType plainBlock[],cipherBlock[],keyBlock[];
     ElemType bKey[];
     ElemType subKeys[][];
     if((plain = fopen(plainFile,"rb")) == NULL){
         return PLAIN_FILE_OPEN_ERROR;
     }
     if((cipher = fopen(cipherFile,"wb")) == NULL){
         return CIPHER_FILE_OPEN_ERROR;
     }
     //设置密钥
     memcpy(keyBlock,keyStr,);
     //将密钥转换为二进制流
     Char8ToBit64(keyBlock,bKey);
     //生成子密钥
     DES_MakeSubKeys(bKey,subKeys);
     while(!feof(plain)){
         //每次读8个字节，并返回成功读取的字节数
         if((count = fread(plainBlock,sizeof(char),,plain)) == ){
             DES_EncryptBlock(plainBlock,subKeys,cipherBlock);
             fwrite(cipherBlock,sizeof(char),,cipher);
         }
     }
     if(count){
         //填充
         memset(plainBlock + count,'\0', - count);
         //最后一个字符保存包括最后一个字符在内的所填充的字符数量
         plainBlock[] =  - count;
         DES_EncryptBlock(plainBlock,subKeys,cipherBlock);
         fwrite(cipherBlock,sizeof(char),,cipher);
     }
     fclose(plain);
     fclose(cipher);
     return OK;
 }

 //解密文件
 int DES_Decrypt(char *cipherFile, char *keyStr,char *plainFile){
     FILE *plain, *cipher;
     int count,times = ;
     long fileLen;
     ElemType plainBlock[],cipherBlock[],keyBlock[];
     ElemType bKey[];
     ElemType subKeys[][];
     if((cipher = fopen(cipherFile,"rb")) == NULL){
         return CIPHER_FILE_OPEN_ERROR;
     }
     if((plain = fopen(plainFile,"wb")) == NULL){
         return PLAIN_FILE_OPEN_ERROR;
     }

     //设置密钥
     memcpy(keyBlock,keyStr,);
     //将密钥转换为二进制流
     Char8ToBit64(keyBlock,bKey);
     //生成子密钥
     DES_MakeSubKeys(bKey,subKeys);

     //取文件长度
     fseek(cipher,,SEEK_END);   //将文件指针置尾
     fileLen = ftell(cipher);    //取文件指针当前位置
     rewind(cipher);             //将文件指针重指向文件头
     while(){
         //密文的字节数一定是8的整数倍
         fread(cipherBlock,sizeof(char),,cipher);
         DES_DecryptBlock(cipherBlock,subKeys,plainBlock);
         times += ;
         if(times < fileLen){
             fwrite(plainBlock,sizeof(char),,plain);
         }
         else{
             break;
         }
     }
     //判断末尾是否被填充
     if(plainBlock[] < ){
         for(count =  - plainBlock[]; count < ; count++){
             if(plainBlock[count] != '\0'){
                 break;
             }
         }
     }
     if(count == ){//有填充
         fwrite(plainBlock,sizeof(char), - plainBlock[],plain);
     }
     else{//无填充
         fwrite(plainBlock,sizeof(char),,plain);
     }

     fclose(plain);
     fclose(cipher);
     return OK;
 }

main.cpp

 #include <iostream>

 #include "DES.h"

 int main(int argc, const char * argv[]) {
     // insert code here...
     std::cout << "CrypDes Start!\n";
     std::cout << "加密文件:res/test_origin.png\n";
     DES_Encrypt("res/test_origin.png","kkkkkkkk","res/test_encrypt.png");
     std::cout << "输出加密文件:res/test_encrypt.png\n";
     std::cout << "解密文件:res/test_encrypt.png\n";
     DES_Decrypt("res/test_encrypt.png","kkkkkkkk","res/test_decrypt.png");
     std::cout << "输出加密文件:res/test_decrypt.png\n";
     return ;
 }

输出：