DES加密算法-C语言

头文件：DES.h

 1 #ifndef DES_hpp
 2 #define DES_hpp
 3 
 4 #include <stdio.h>
 5 #include <memory.h>
 6 #include <time.h>
 7 #include <stdlib.h>
 8 
 9 #define PLAIN_FILE_OPEN_ERROR -1
10 #define KEY_FILE_OPEN_ERROR -2
11 #define CIPHER_FILE_OPEN_ERROR -3
12 #define OK 1
13 
14 typedef char ElemType;
15 
16 int ByteToBit(ElemType ch,ElemType bit[8]);
17 int BitToByte(ElemType bit[8],ElemType *ch);
18 int Char8ToBit64(ElemType ch[8],ElemType bit[64]);
19 int Bit64ToChar8(ElemType bit[64],ElemType ch[8]);
20 int DES_MakeSubKeys(ElemType key[64],ElemType subKeys[16][48]);
21 int DES_PC1_Transform(ElemType key[64], ElemType tempbts[56]);
22 int DES_PC2_Transform(ElemType key[56], ElemType tempbts[48]);
23 int DES_ROL(ElemType data[56], int time);
24 int DES_IP_Transform(ElemType data[64]);
25 int DES_IP_1_Transform(ElemType data[64]);
26 int DES_E_Transform(ElemType data[48]);
27 int DES_P_Transform(ElemType data[32]);
28 int DES_SBOX(ElemType data[48]);
29 int DES_XOR(ElemType R[48], ElemType L[48],int count);
30 int DES_Swap(ElemType left[32],ElemType right[32]);
31 int DES_EncryptBlock(ElemType plainBlock[8], ElemType subKeys[16][48], ElemType cipherBlock[8]);
32 int DES_DecryptBlock(ElemType cipherBlock[8], ElemType subKeys[16][48], ElemType plainBlock[8]);
33 int DES_Encrypt(char *plainFile, char *keyStr,char *cipherFile);
34 int DES_Decrypt(char *cipherFile, char *keyStr,char *plainFile);
35 
36 #endif /* DES_hpp */

View Code

C代码：DES.cpp

  1 #include "DES.h"
  2 
  3 //初始置换表IP
  4 int IP_Table[64] = {  57,49,41,33,25,17,9,1,
  5     59,51,43,35,27,19,11,3,
  6     61,53,45,37,29,21,13,5,
  7     63,55,47,39,31,23,15,7,
  8     56,48,40,32,24,16,8,0,
  9     58,50,42,34,26,18,10,2,
 10     60,52,44,36,28,20,12,4,
 11     62,54,46,38,30,22,14,6};
 12 //逆初始置换表IP^-1
 13 int IP_1_Table[64] = {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     32,0,40,8,48,16,56,24};
 21 
 22 //扩充置换表E
 23 int E_Table[48] = {31, 0, 1, 2, 3, 4,
 24     3,  4, 5, 6, 7, 8,
 25     7,  8,9,10,11,12,
 26     11,12,13,14,15,16,
 27     15,16,17,18,19,20,
 28     19,20,21,22,23,24,
 29     23,24,25,26,27,28,
 30     27,28,29,30,31, 0};
 31 
 32 //置换函数P
 33 int P_Table[32] = {15,6,19,20,28,11,27,16,
 34     0,14,22,25,4,17,30,9,
 35     1,7,23,13,31,26,2,8,
 36     18,12,29,5,21,10,3,24};
 37 
 38 //S盒
 39 int S[8][4][16] =//S1
 40 {{{14,4,13,1,2,15,11,8,3,10,6,12,5,9,0,7},
 41     {0,15,7,4,14,2,13,1,10,6,12,11,9,5,3,8},
 42     {4,1,14,8,13,6,2,11,15,12,9,7,3,10,5,0},
 43     {15,12,8,2,4,9,1,7,5,11,3,14,10,0,6,13}},
 44     //S2
 45     {{15,1,8,14,6,11,3,4,9,7,2,13,12,0,5,10},
 46         {3,13,4,7,15,2,8,14,12,0,1,10,6,9,11,5},
 47         {0,14,7,11,10,4,13,1,5,8,12,6,9,3,2,15},
 48         {13,8,10,1,3,15,4,2,11,6,7,12,0,5,14,9}},
 49     //S3
 50     {{10,0,9,14,6,3,15,5,1,13,12,7,11,4,2,8},
 51         {13,7,0,9,3,4,6,10,2,8,5,14,12,11,15,1},
 52         {13,6,4,9,8,15,3,0,11,1,2,12,5,10,14,7},
 53         {1,10,13,0,6,9,8,7,4,15,14,3,11,5,2,12}},
 54     //S4
 55     {{7,13,14,3,0,6,9,10,1,2,8,5,11,12,4,15},
 56         {13,8,11,5,6,15,0,3,4,7,2,12,1,10,14,9},
 57         {10,6,9,0,12,11,7,13,15,1,3,14,5,2,8,4},
 58         {3,15,0,6,10,1,13,8,9,4,5,11,12,7,2,14}},
 59     //S5
 60     {{2,12,4,1,7,10,11,6,8,5,3,15,13,0,14,9},
 61         {14,11,2,12,4,7,13,1,5,0,15,10,3,9,8,6},
 62         {4,2,1,11,10,13,7,8,15,9,12,5,6,3,0,14},
 63         {11,8,12,7,1,14,2,13,6,15,0,9,10,4,5,3}},
 64     //S6
 65     {{12,1,10,15,9,2,6,8,0,13,3,4,14,7,5,11},
 66         {10,15,4,2,7,12,9,5,6,1,13,14,0,11,3,8},
 67         {9,14,15,5,2,8,12,3,7,0,4,10,1,13,11,6},
 68         {4,3,2,12,9,5,15,10,11,14,1,7,6,0,8,13}},
 69     //S7
 70     {{4,11,2,14,15,0,8,13,3,12,9,7,5,10,6,1},
 71         {13,0,11,7,4,9,1,10,14,3,5,12,2,15,8,6},
 72         {1,4,11,13,12,3,7,14,10,15,6,8,0,5,9,2},
 73         {6,11,13,8,1,4,10,7,9,5,0,15,14,2,3,12}},
 74     //S8
 75     {{13,2,8,4,6,15,11,1,10,9,3,14,5,0,12,7},
 76         {1,15,13,8,10,3,7,4,12,5,6,11,0,14,9,2},
 77         {7,11,4,1,9,12,14,2,0,6,10,13,15,3,5,8},
 78         {2,1,14,7,4,10,8,13,15,12,9,0,3,5,6,11}}};
 79 //置换选择1
 80 int PC_1[56] = {56,48,40,32,24,16,8,
 81     0,57,49,41,33,25,17,
 82     9,1,58,50,42,34,26,
 83     18,10,2,59,51,43,35,
 84     62,54,46,38,30,22,14,
 85     6,61,53,45,37,29,21,
 86     13,5,60,52,44,36,28,
 87     20,12,4,27,19,11,3};
 88 
 89 //置换选择2
 90 int PC_2[48] = {13,16,10,23,0,4,2,27,
 91     14,5,20,9,22,18,11,3,
 92     25,7,15,6,26,19,12,1,
 93     40,51,30,36,46,54,29,39,
 94     50,44,32,46,43,48,38,55,
 95     33,52,45,41,49,35,28,31};
 96 
 97 //对左移次数的规定
 98 int MOVE_TIMES[16] = {1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1};
 99 
100 //字节转换成二进制
101 int ByteToBit(ElemType ch, ElemType bit[8]){
102     int cnt;
103     for(cnt = 0;cnt < 8; cnt++){
104         *(bit+cnt) = (ch>>cnt)&1;
105     }
106     return 0;
107 }
108 
109 //二进制转换成字节
110 int BitToByte(ElemType bit[8],ElemType *ch){
111     int cnt;
112     for(cnt = 0;cnt < 8; cnt++){
113         *ch |= *(bit + cnt)<<cnt;
114     }
115     return 0;
116 }
117 
118 //将长度为8的字符串转为二进制位串
119 int Char8ToBit64(ElemType ch[8],ElemType bit[64]){
120     int cnt;
121     for(cnt = 0; cnt < 8; cnt++){
122         ByteToBit(*(ch+cnt),bit+(cnt<<3));
123     }
124     return 0;
125 }
126 
127 //将二进制位串转为长度为8的字符串
128 int Bit64ToChar8(ElemType bit[64],ElemType ch[8]){
129     int cnt;
130     memset(ch,0,8);
131     for(cnt = 0; cnt < 8; cnt++){
132         BitToByte(bit+(cnt<<3),ch+cnt);
133     }
134     return 0;
135 }
136 
137 //生成子密钥
138 int DES_MakeSubKeys(ElemType key[64],ElemType subKeys[16][48]){
139     ElemType temp[56];
140     int cnt;
141     DES_PC1_Transform(key,temp);//PC1置换
142     for(cnt = 0; cnt < 16; cnt++){//16轮跌代，产生16个子密钥
143         DES_ROL(temp,MOVE_TIMES[cnt]);//循环左移
144         DES_PC2_Transform(temp,subKeys[cnt]);//PC2置换，产生子密钥
145     }
146     return 0;
147 }
148 
149 //密钥置换1
150 int DES_PC1_Transform(ElemType key[64], ElemType tempbts[56]){
151     int cnt;
152     for(cnt = 0; cnt < 56; cnt++){
153         tempbts[cnt] = key[PC_1[cnt]];
154     }
155     return 0;
156 }
157 
158 //密钥置换2
159 int DES_PC2_Transform(ElemType key[56], ElemType tempbts[48]){
160     int cnt;
161     for(cnt = 0; cnt < 48; cnt++){
162         tempbts[cnt] = key[PC_2[cnt]];
163     }
164     return 0;
165 }
166 
167 //循环左移
168 int DES_ROL(ElemType data[56], int time){
169     ElemType temp[56];
170     
171     //保存将要循环移动到右边的位
172     memcpy(temp,data,time);
173     memcpy(temp+time,data+28,time);
174     
175     //前28位移动
176     memcpy(data,data+time,28-time);
177     memcpy(data+28-time,temp,time);
178     
179     //后28位移动
180     memcpy(data+28,data+28+time,28-time);
181     memcpy(data+56-time,temp+time,time);
182     
183     return 0;
184 }
185 
186 //IP置换
187 int DES_IP_Transform(ElemType data[64]){
188     int cnt;
189     ElemType temp[64];
190     for(cnt = 0; cnt < 64; cnt++){
191         temp[cnt] = data[IP_Table[cnt]];
192     }
193     memcpy(data,temp,64);
194     return 0;
195 }
196 
197 //IP逆置换
198 int DES_IP_1_Transform(ElemType data[64]){
199     int cnt;
200     ElemType temp[64];
201     for(cnt = 0; cnt < 64; cnt++){
202         temp[cnt] = data[IP_1_Table[cnt]];
203     }
204     memcpy(data,temp,64);
205     return 0;
206 }
207 
208 //扩展置换
209 int DES_E_Transform(ElemType data[48]){
210     int cnt;
211     ElemType temp[48];
212     for(cnt = 0; cnt < 48; cnt++){
213         temp[cnt] = data[E_Table[cnt]];
214     }
215     memcpy(data,temp,48);
216     return 0;
217 }
218 
219 //P置换
220 int DES_P_Transform(ElemType data[32]){
221     int cnt;
222     ElemType temp[32];
223     for(cnt = 0; cnt < 32; cnt++){
224         temp[cnt] = data[P_Table[cnt]];
225     }
226     memcpy(data,temp,32);
227     return 0;
228 }
229 
230 //异或
231 int DES_XOR(ElemType R[48], ElemType L[48] ,int count){
232     int cnt;
233     for(cnt = 0; cnt < count; cnt++){
234         R[cnt] ^= L[cnt];
235     }
236     return 0;
237 }
238 
239 //S盒置换
240 int DES_SBOX(ElemType data[48]){
241     int cnt;
242     int line,row,output;
243     int cur1,cur2;
244     for(cnt = 0; cnt < 8; cnt++){
245         cur1 = cnt*6;
246         cur2 = cnt<<2;
247         
248         //计算在S盒中的行与列
249         line = (data[cur1]<<1) + data[cur1+5];
250         row = (data[cur1+1]<<3) + (data[cur1+2]<<2)
251         + (data[cur1+3]<<1) + data[cur1+4];
252         output = S[cnt][line][row];
253         
254         //化为2进制
255         data[cur2] = (output&0X08)>>3;
256         data[cur2+1] = (output&0X04)>>2;
257         data[cur2+2] = (output&0X02)>>1;
258         data[cur2+3] = output&0x01;
259     }
260     return 0;
261 }
262 
263 //交换
264 int DES_Swap(ElemType left[32], ElemType right[32]){
265     ElemType temp[32];
266     memcpy(temp,left,32);
267     memcpy(left,right,32);
268     memcpy(right,temp,32);
269     return 0;
270 }
271 
272 //加密单个分组
273 int DES_EncryptBlock(ElemType plainBlock[8], ElemType subKeys[16][48], ElemType cipherBlock[8]){
274     ElemType plainBits[64];
275     ElemType copyRight[48];
276     int cnt;
277     
278     Char8ToBit64(plainBlock,plainBits);
279     //初始置换（IP置换）
280     DES_IP_Transform(plainBits);
281     
282     //16轮迭代
283     for(cnt = 0; cnt < 16; cnt++){
284         memcpy(copyRight,plainBits+32,32);
285         //将右半部分进行扩展置换，从32位扩展到48位
286         DES_E_Transform(copyRight);
287         //将右半部分与子密钥进行异或操作
288         DES_XOR(copyRight,subKeys[cnt],48);
289         //异或结果进入S盒，输出32位结果
290         DES_SBOX(copyRight);
291         //P置换
292         DES_P_Transform(copyRight);
293         //将明文左半部分与右半部分进行异或
294         DES_XOR(plainBits,copyRight,32);
295         if(cnt != 15){
296             //最终完成左右部的交换
297             DES_Swap(plainBits,plainBits+32);
298         }
299     }
300     //逆初始置换（IP^1置换）
301     DES_IP_1_Transform(plainBits);
302     Bit64ToChar8(plainBits,cipherBlock);
303     return 0;
304 }
305 
306 //解密单个分组
307 int DES_DecryptBlock(ElemType cipherBlock[8], ElemType subKeys[16][48],ElemType plainBlock[8]){
308     ElemType cipherBits[64];
309     ElemType copyRight[48];
310     int cnt;
311     
312     Char8ToBit64(cipherBlock,cipherBits);
313     //初始置换（IP置换）
314     DES_IP_Transform(cipherBits);
315     
316     //16轮迭代
317     for(cnt = 15; cnt >= 0; cnt--){
318         memcpy(copyRight,cipherBits+32,32);
319         //将右半部分进行扩展置换，从32位扩展到48位
320         DES_E_Transform(copyRight);
321         //将右半部分与子密钥进行异或操作
322         DES_XOR(copyRight,subKeys[cnt],48);
323         //异或结果进入S盒，输出32位结果
324         DES_SBOX(copyRight);
325         //P置换
326         DES_P_Transform(copyRight);
327         //将明文左半部分与右半部分进行异或
328         DES_XOR(cipherBits,copyRight,32);
329         if(cnt != 0){
330             //最终完成左右部的交换
331             DES_Swap(cipherBits,cipherBits+32);
332         }
333     }
334     //逆初始置换（IP^1置换）
335     DES_IP_1_Transform(cipherBits);
336     Bit64ToChar8(cipherBits,plainBlock);
337     return 0;
338 }
339 
340 //加密文件
341 int DES_Encrypt(char *plainFile, char *keyStr,char *cipherFile){
342     FILE *plain,*cipher;
343     int count;
344     ElemType plainBlock[8],cipherBlock[8],keyBlock[8];
345     ElemType bKey[64];
346     ElemType subKeys[16][48];
347     if((plain = fopen(plainFile,"rb")) == NULL){
348         return PLAIN_FILE_OPEN_ERROR;
349     }
350     if((cipher = fopen(cipherFile,"wb")) == NULL){
351         return CIPHER_FILE_OPEN_ERROR;
352     }
353     //设置密钥
354     memcpy(keyBlock,keyStr,8);
355     //将密钥转换为二进制流
356     Char8ToBit64(keyBlock,bKey);
357     //生成子密钥
358     DES_MakeSubKeys(bKey,subKeys);
359     while(!feof(plain)){
360         //每次读8个字节，并返回成功读取的字节数
361         if((count = fread(plainBlock,sizeof(char),8,plain)) == 8){
362             DES_EncryptBlock(plainBlock,subKeys,cipherBlock);
363             fwrite(cipherBlock,sizeof(char),8,cipher);
364         }
365     }
366     if(count){
367         //填充
368         memset(plainBlock + count,'\0',7 - count);
369         //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
370         plainBlock[7] = 8 - count;
371         DES_EncryptBlock(plainBlock,subKeys,cipherBlock);
372         fwrite(cipherBlock,sizeof(char),8,cipher);
373     }
374     fclose(plain);
375     fclose(cipher);
376     return OK;
377 }
378 
379 //解密文件
380 int DES_Decrypt(char *cipherFile, char *keyStr,char *plainFile){
381     FILE *plain, *cipher;
382     int count,times = 0;
383     long fileLen;
384     ElemType plainBlock[8],cipherBlock[8],keyBlock[8];
385     ElemType bKey[64];
386     ElemType subKeys[16][48];
387     if((cipher = fopen(cipherFile,"rb")) == NULL){
388         return CIPHER_FILE_OPEN_ERROR;
389     }
390     if((plain = fopen(plainFile,"wb")) == NULL){
391         return PLAIN_FILE_OPEN_ERROR;
392     }
393     
394     //设置密钥
395     memcpy(keyBlock,keyStr,8);
396     //将密钥转换为二进制流
397     Char8ToBit64(keyBlock,bKey);
398     //生成子密钥
399     DES_MakeSubKeys(bKey,subKeys);
400     
401     //取文件长度
402     fseek(cipher,0,SEEK_END);   //将文件指针置尾
403     fileLen = ftell(cipher);    //取文件指针当前位置
404     rewind(cipher);             //将文件指针重指向文件头
405     while(1){
406         //密文的字节数一定是8的整数倍
407         fread(cipherBlock,sizeof(char),8,cipher);
408         DES_DecryptBlock(cipherBlock,subKeys,plainBlock);
409         times += 8;
410         if(times < fileLen){
411             fwrite(plainBlock,sizeof(char),8,plain);
412         }
413         else{
414             break;
415         }
416     }
417     //判断末尾是否被填充
418     if(plainBlock[7] < 8){
419         for(count = 8 - plainBlock[7]; count < 7; count++){
420             if(plainBlock[count] != '\0'){
421                 break;
422             }
423         }
424     }
425     if(count == 7){//有填充
426         fwrite(plainBlock,sizeof(char),8 - plainBlock[7],plain);
427     }
428     else{//无填充
429         fwrite(plainBlock,sizeof(char),8,plain);
430     }
431     
432     fclose(plain);
433     fclose(cipher);
434     return OK;
435 }

View Code

 main.cpp

 1 #include <iostream>
 2 
 3 #include "DES.h"
 4 
 5 int main(int argc, const char * argv[]) {
 6     // insert code here...
 7     std::cout << "CrypDes Start!\n";
 8     std::cout << "加密文件:res/test_origin.png\n";
 9     DES_Encrypt("res/test_origin.png","kkkkkkkk","res/test_encrypt.png");
10     std::cout << "输出加密文件:res/test_encrypt.png\n";
11     std::cout << "解密文件:res/test_encrypt.png\n";
12     DES_Decrypt("res/test_encrypt.png","kkkkkkkk","res/test_decrypt.png");
13     std::cout << "输出加密文件:res/test_decrypt.png\n";
14     return 0;
15 }

View Code

输出：