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c语言编写的一个des加密源程序如下，不解释，自己慢慢看：
c语言编写的一个des加密源程序如下，不解释，自己慢慢看：
#include
#include
#include
#include
#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 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};
int 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};
int 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};
int p_table[32] = {15,6,19,20,28,11,27,16,
0,14,22,25,4,17,30,9,
1,7,23,13,31,26,2,8,
18,12,29,5,21,10,3,24};
int 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 */
{{15,1,8,14,6,11,3,4,9,7,2,13,12,0,5,10},
{3,13,4,7,15,2,8,14,12,0,1,10,6,9,11,5},
{0,14,7,11,10,4,13,1,5,8,12,6,9,3,2,15},
{13,8,10,1,3,15,4,2,11,6,7,12,0,5,14,9}},
/* s3 */
{{10,0,9,14,6,3,15,5,1,13,12,7,11,4,2,8},
{13,7,0,9,3,4,6,10,2,8,5,14,12,11,15,1},
{13,6,4,9,8,15,3,0,11,1,2,12,5,10,14,7},
{1,10,13,0,6,9,8,7,4,15,14,3,11,5,2,12}},
/* s4 */
{{7,13,14,3,0,6,9,10,1,2,8,5,11,12,4,15},
{13,8,11,5,6,15,0,3,4,7,2,12,1,10,14,9},
{10,6,9,0,12,11,7,13,15,1,3,14,5,2,8,4},
{3,15,0,6,10,1,13,8,9,4,5,11,12,7,2,14}},
/* s5 */
{{2,12,4,1,7,10,11,6,8,5,3,15,13,0,14,9},
{14,11,2,12,4,7,13,1,5,0,15,10,3,9,8,6},
{4,2,1,11,10,13,7,8,15,9,12,5,6,3,0,14},
{11,8,12,7,1,14,2,13,6,15,0,9,10,4,5,3}},
/* s6 */
{{12,1,10,15,9,2,6,8,0,13,3,4,14,7,5,11},
{10,15,4,2,7,12,9,5,6,1,13,14,0,11,3,8},
{9,14,15,5,2,8,12,3,7,0,4,10,1,13,11,6},
{4,3,2,12,9,5,15,10,11,14,1,7,6,0,8,13}},
/* s7 */
{{4,11,2,14,15,0,8,13,3,12,9,7,5,10,6,1},
{13,0,11,7,4,9,1,10,14,3,5,12,2,15,8,6},
{1,4,11,13,12,3,7,14,10,15,6,8,0,5,9,2},
{6,11,13,8,1,4,10,7,9,5,0,15,14,2,3,12}},
/* s8 */
{{13,2,8,4,6,15,11,1,10,9,3,14,5,0,12,7},
{1,15,13,8,10,3,7,4,12,5,6,11,0,14,9,2},
{7,11,4,1,9,12,14,2,0,6,10,13,15,3,5,8},
{2,1,14,7,4,10,8,13,15,12,9,0,3,5,6,11}}};
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};
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};
int move_times[16] = {1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1};
int bytetobit(elemtype ch,elemtype bit[8]);
int bittobyte(elemtype bit[8],elemtype *ch);
int char8tobit64(elemtype ch[8],elemtype bit[64]);
int bit64tochar8(elemtype bit[64],elemtype ch[8]);
int des_makesubkeys(elemtype key[64],elemtype subkeys[16][48]);
int des_pc1_transform(elemtype key[64], elemtype tempbts[56]);
int des_pc2_transform(elemtype key[56], elemtype tempbts[48]);
int des_rol(elemtype data[56], int time);
int des_ip_transform(elemtype data[64]);
int des_ip_1_transform(elemtype data[64]);
int des_e_transform(elemtype data[48]);
int des_p_transform(elemtype data[32]);
int des_sbox(elemtype data[48]);
int des_xor(elemtype r[48], elemtype l[48],int count);
int des_swap(elemtype left[32],elemtype right[32]);
int des_encryptblock(elemtype plainblock[8], elemtype subkeys[16][48], elemtype cipherblock[8]);
int des_decryptblock(elemtype cipherblock[8], elemtype subkeys[16][48], elemtype plainblock[8]);
int des_encrypt(char *plainfile, char *keystr,char *cipherfile);
int des_decrypt(char *cipherfile, char *keystr,char *plainfile);
int bytetobit(elemtype ch, elemtype bit[8]){
int cnt;
for(cnt = 0;cnt < 8; cnt++){
*(bit+cnt) = (ch>>cnt)&1;
}
return 0;
}
/* 娴滃矁绻橀崚鎯版祮阉广垺鍨氱€涙 濡?*/
int bittobyte(elemtype bit[8],elemtype *ch){
int cnt;
for(cnt = 0;cnt < 8; cnt++){
*ch |= *(bit + cnt)<>3;
data[cur2+1] = (output&0x04)>>2;
data[cur2+2] = (output&0x02)>>1;
data[cur2+3] = output&0x01;
}
return 0;
}
int des_swap(elemtype left[32], elemtype right[32]){
elemtype temp[32];
memcpy(temp,left,32);
memcpy(left,right,32);
memcpy(right,temp,32);
return 0;
}
int des_encryptblock(elemtype plainblock[8], elemtype subkeys[16][48], elemtype cipherblock[8]){
elemtype plainbits[64];
elemtype copyright[48];
int cnt;
char8tobit64(plainblock,plainbits);
des_ip_transform(plainbits);
for(cnt = 0; cnt < 16; cnt++){
memcpy(copyright,plainbits+32,32);
des_e_transform(copyright);
des_xor(copyright,subkeys[cnt],48);
des_sbox(copyright);
des_p_transform(copyright);
des_xor(plainbits,copyright,32);
if(cnt != 15){
des_swap(plainbits,plainbits+32);
}
}
des_ip_1_transform(plainbits);
bit64tochar8(plainbits,cipherblock);
return 0;
}
int des_decryptblock(elemtype cipherblock[8], elemtype subkeys[16][48],elemtype plainblock[8]){
elemtype cipherbits[64];
elemtype copyright[48];
int cnt;
char8tobit64(cipherblock,cipherbits);
des_ip_transform(cipherbits);
for(cnt = 15; cnt >= 0; cnt--){
memcpy(copyright,cipherbits+32,32);
des_e_transform(copyright);
des_xor(copyright,subkeys[cnt],48);
des_sbox(copyright);
des_p_transform(copyright);
des_xor(cipherbits,copyright,32);
if(cnt != 0){
des_swap(cipherbits,cipherbits+32);
}
}
des_ip_1_transform(cipherbits);
bit64tochar8(cipherbits,plainblock);
return 0;
}
int des_encrypt(char *plainfile, char *keystr,char *cipherfile){
file *plain,*cipher;
int count;
elemtype plainblock[8],cipherblock[8],keyblock[8];
elemtype bkey[64];
elemtype subkeys[16][48];
if((plain = fopen(plainfile,"rb")) == null){
return plain_file_open_error;
}
if((cipher = fopen(cipherfile,"wb")) == null){
return cipher_file_open_error;
}
memcpy(keyblock,keystr,8);
char8tobit64(keyblock,bkey);
des_makesubkeys(bkey,subkeys);
while(!feof(plain)){
if((count = fread(plainblock,sizeof(char),8,plain)) == 8){
des_encryptblock(plainblock,subkeys,cipherblock);
fwrite(cipherblock,sizeof(char),8,cipher);
}
}
if(count){
memset(plainblock + count,'\0',7 - count);
plainblock[7] = 8 - count;
des_encryptblock(plainblock,subkeys,cipherblock);
fwrite(cipherblock,sizeof(char),8,cipher);
}
fclose(plain);
fclose(cipher);
return ok;
}
int des_decrypt(char *cipherfile, char *keystr,char *plainfile){
file *plain, *cipher;
int count,times = 0;
long filelen;
elemtype plainblock[8],cipherblock[8],keyblock[8];
elemtype bkey[64];
elemtype subkeys[16][48];
if((cipher = fopen(cipherfile,"rb")) == null){
return cipher_file_open_error;
}
if((plain = fopen(plainfile,"wb")) == null){
return plain_file_open_error;
}
memcpy(keyblock,keystr,8);
char8tobit64(keyblock,bkey);
des_makesubkeys(bkey,subkeys);
fseek(cipher,0,seek_end);
filelen = ftell(cipher);
rewind(cipher);
while(1){
fread(cipherblock,sizeof(char),8,cipher);
des_decryptblock(cipherblock,subkeys,plainblock);
times += 8;
if(times < filelen){
fwrite(plainblock,sizeof(char),8,plain);
}
else{
break;
}
}
if(plainblock[7] < 8){
for(count = 8 - plainblock[7]; count < 7; count++){
if(plainblock[count] != '\0'){
break;
}
}
}
if(count == 7){
fwrite(plainblock,sizeof(char),8 - plainblock[7],plain);
}
else{
fwrite(plainblock,sizeof(char),8,plain);
}
fclose(plain);
fclose(cipher);
return ok;
}
int main()
{
des_encrypt("out.xml","key.txt","out.des");
des_decrypt("out.des","key.txt","out.des.xml");
return 0;
} ;>
那个需要加密狗（就是那个U盘状的东西）和前面的一台大箱子 （平时当交换机使用），这样程序就是注册了