DES加密算法的介绍与C语言实现

//作者：高金山 //日期：2004年3月 //说明：本文件包含了DES加密解密的函数。 //循环移位表,PC-1表,PC-2表,IP表,IP-1表, //E扩展表,P变换表,S盒等都可以自己设置 #define g_RUN_ON_PC//pc上运行的标志 #ifndef g_RUN_ON_PC #include "release.h" #else #include "stdlib.h" #define bmalloc malloc #endif #include "gjsDES.h" #include "gjsBase64.h" void xTran(unsigned char q[8],unsigned char p[8],unsigned char xTab[],int xLen) {//根据置换表xTab将64位q转换成p int i,qt,pt,tt;//qt,pt分别表示q,p的第几个字节,tt暂存 for(i=0;i<8;i++) p[i]=0;//先清零 for(i=0;i<xLen;i++) {//循环置位 pt=i/8; qt=(xTab[i]-1)/8; tt=q[qt] << ((xTab[i]-1) % 8); tt=tt & 0x80;//1000 0000 tt=tt >> (i % 8); p[pt]=p[pt] | tt; } } void genKey(unsigned char *key,unsigned char nkey[16][8]) {//由初始密钥okey生成16个子密钥nkey unsigned char movebit[16]={//循环移位表。 1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1}; unsigned char pc_1[56]={//PC-1置换。 57,49,41,33,25,17,9, 1,58,50,42,34,26,18, 10,2,59,51,43,35,27, 19,11,3,60,52,44,36, 63,55,47,39,31,23,15, 7,62,54,46,38,30,22, 14,6,61,53,45,37,29, 21,13,5,28,20,12,4}; unsigned char pc_2[48]={//PC-2置换。 14,17,11,24,1,5, 3,28,15,6,21,10, 23,19,12,4,26,8, 16,7,27,20,13,2, 41,52,31,37,47,55, 30,40,51,45,33,48, 44,49,39,56,34,53, 46,42,50,36,29,32}; unsigned char tkey[8],tt[8];//暂存64字节 unsigned long key_c,key_d; //前28位,后28位 int i=0,j=0; for(i=0;i<8;i++) tkey[i]=0; i=0;//strcpy(tkey,key); while((*(key+i)!='\0')&&(i<8)) { tkey[i]=*(key+i);i++; } xTran(tkey,tt,pc_1,56); //PC-1置换 key_c=(*(tt+0)<<24)+(*(tt+1)<<16)+(*(tt+2)<<8)+(*(tt+3)); key_c=key_c & 0xfffffff0;//将前28位移入key_c的高28位 key_d=(*(tt+3)<<24)+(*(tt+4)<<16)+(*(tt+5)<<8)+(*(tt+6)); key_d=key_d & 0x0fffffff;//将后28位移入key_d低28位 for(i=0;i<16;i++) { //移位以得到各个子密钥 //根据移位表对c,d进行循环左移 key_c=(key_c<<movebit[i]) | ((key_c>>(28-movebit[i])) & 0xfffffff0); key_d=((key_d<<movebit[i])& 0x0fffffff) | (key_d>>(28-movebit[i])); for(j=0;j<8;j++) tt[j]=0;//清零 *(tt+0)=key_c>>24;*(tt+1)=key_c>>16; *(tt+2)=key_c>>8;*(tt+3)=key_c;//合并c到tt *(tt+3)|=(key_d>>24);*(tt+4)=key_d>>16; *(tt+5)=key_d>>8;*(tt+6)=key_d;//合并d到tt xTran(tt,nkey[i],pc_2,48);//PC-2置换 } }//生产子密钥结束 void sReplace(unsigned char right_s[8]) {//查找S盒，把扩展成48位的数据，替换成32位的数据 unsigned char p[32]={//P置换。 16,7,20,21, 29,12,28,17, 1,15,23,26, 5,18,31,10, 2,8,24,14, 32,27,3,9, 19,13,30,6, 22,11,4,25 } ; unsigned char s[][4][16] = {{//S盒1。 S盒都可以自己设置 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 }, {//S盒2 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 }, {//S盒3 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 }, {//S盒4 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 }, { //S盒5 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 }, {//S盒6 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 }, {//S盒7 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 }, {//S盒8 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 }}; unsigned char row,col,tmp_s[8]={0,0,0,0,0,0,0,0}; unsigned short tt; int i=0; for(i=0;i<=7;i++) {//从S盒中取数 row=0,col=0;tt=0; tt=((right_s[i*6/8]<<8) + (right_s[i*6/8+1])) >> (10-i*6 % 8);//取六位放到tt低6位 row=(row | ((tt>>5) & 0x01)) << 1;//取6位的第0位付给row的6位 row=(row | ((tt>>0) & 0x01)) << 0;//取6位的第5位付给row的7位 col=(tt >> 1) & 0x0f;//取6位的第1,2,3,4位付给row的低四位 //根据行和列的值从S盒中取数 tmp_s[i/2]=tmp_s[i/2]|s[i][row][col]<<4*((i+1)%2); } //s_out[0-3]:???????? ???????? ???????? ???????? 00000000... xTran(tmp_s,right_s,p,32); //P置换 }//S代替的结束 #define g_ENCRYPT_FLAG 1 #define g_DECRYPT_FLAG 2 unsigned char comDES(unsigned char in[8],unsigned char out[8], unsigned char subkey[16][8],unsigned char flg) {//单重DES加解密的公共函数 in输入数据 key密钥 out输出数据 unsigned char ip[64]={////IP置换。 58,50,42,34,26,18,10,2, 60,52,44,36,28,20,12,4, 62,54,46,38,30,22,14,6, 64,56,48,40,32,24,16,8, 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 }; unsigned char ip_1[64]={//IP-1置换。可根据IP表生成 40,8,48,16,56,24,64,32, 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 }; unsigned char e[48] ={//E扩展。 32,1, 2, 3, 4, 5, 4, 5, 6, 7, 8, 9, 8, 9, 10,11,12,13, 12,13,14,15,16,17, 16,17,18,19,20,21, 20,21,22,23,24,25, 24,25,26,27,28,29, 28,29,30,31,32,1}; unsigned char left[8],right[8],temp[8];//数据的左32位,右32位,暂存 int i=0,j=0,k=0; xTran(in,temp,ip,64); //IP置换 for(i=0;i<=3;i++) left[i]=temp[i] ;//将明文左32位放到left中 for(i=4;i<=7;i++) right[i-4]=temp[i] ;//将明文右32位放到right中 for(i=0;i<16;i++) {//16层循环 if(flg==g_ENCRYPT_FLAG) k=i; else if(flg==g_DECRYPT_FLAG) k=15-i; else return 0; for(j=0;j<=3;j++) { temp[j]=left[j];//将left暂存起来 left[j]=right[j];//L(n) = R(n-1) } xTran(left,right,e,48);//对right进行E扩展 for(j=0;j<6;j++) right[j]=right[j]^subkey[k][j];//48位的数据右部与密钥异或 sReplace(right) ;//将48位的right变为32位 for(j=0;j<=3;j++) {//获得下一个right right[j]=temp[j] ^ right[j] ;//f(R(n-1),k) } } for(i=0;i<4;i++) temp[i]=right[i]; //合并right和left到temp(64位) for(i=4;i<8;i++) temp[i]=left[i-4];//右边左边互换,因为最后一次不用交换 //for(i=0;i<64;i++) ip_1[ip[i]-1]=i+1;//生成IP-1置换表 xTran(temp,out,ip_1,64);//IP-1置换 return 1; }//单重DES加解密结束 //=======================================DES==================================== unsigned char enDES(unsigned char* indata,unsigned long inlen,unsigned char* key,\ unsigned char* outdata,unsigned long* outlen) {//加密 unsigned char *p,*p1,s_key[16][8],tt[8]; long tlen=0,i=0,ttlen=0,tc=0; if((indata==NULL)||(outdata==NULL)||(key==NULL) ||(outlen==NUL