des.cpp

这是我上信息安全课做的作业

#include<memory.h>
#include<stdio.h>
enum{encrypt,decrypt};                  //encrypt:加密，decrypt：解密
void des_run(char out[8],char[8],bool type=encrypt);
void des_setkey(const char key[8]);    //设置密钥
static void f_func(bool in[32],const bool ki[48]);  //f函数
static void s_func(bool out[32],const bool in[48]); //s盒代替
static void transform(bool *out,bool *in,const char *table,int len); //变换
static void xor(bool *ina,const bool *inb,int len); //异或
static void rotatel(bool *in,int len,int loop);     //循环左移
static void bytetobit(bool *out,const char *in,int bits);//字节组转换成位组 
static void bittobyte(char *out,const bool *in,int bits);//位组转换成字节组
//置换IP表 
const static char ip_table[64]={
	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};
//逆置换IP表
const static char ipr_table[64]={
	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};
//E位选择表
const static char e_table[48]={
	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};
//P换位表
const static char p_table[32]={
	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};
//PC1选位表
const static char pc1_table[56]={
	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};
//PC2选位表
const static char pc2_table[48]={
	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};
//左移位数表
const static char loop_table[16]={
    1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1};
//s盒
const static char s_box[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};
static bool subkey[16][48];//16圈子密钥
void des_run(char out[8],char in[8],bool type)
{
	static bool m[64],tmp[32],*li=&m[0],*ri=&m[32];
	bytetobit(m,in,64);
	transform(m,m,ip_table,64);
	if(type==encrypt){             //加密
		for(int i=0;i<16;i++){
			memcpy(tmp,ri,32);
			f_func(ri,subkey[i]);
			xor(ri,li,32);
			memcpy(li,tmp,32);
		}
	}else{
		for(int i=15;i>=0;i--){    //解密，解密子密钥顺序与加密子密钥相反
			memcpy(tmp,li,32);
			f_func(li,subkey[i]);
			xor(li,ri,32);
			memcpy(ri,tmp,32);
		}
	}
	transform(m,m,ipr_table,64);
	bittobyte(out,m,64);
}
void des_setkey(const char key[8])
{
	static bool k[64],*kl=&k[0],*kr=&k[28];
	bytetobit(k,key,64);
	transform(k,k,pc1_table,56);
	for(int i=0;i<16;i++){
		rotatel(kl,28,loop_table[i]);
		rotatel(kr,28,loop_table[i]);
		transform(subkey[i],k,pc2_table,48);
	}
}
void f_func(bool in[32],const bool ki[48])
{ 
	static bool mr[48];
	transform (mr,in,e_table,48);
    xor(mr,ki,48);
	s_func(in,mr);
	transform(in,in,p_table,32);
}
void s_func(bool out[32],const bool in[48])
{
	for(char i=0,j,k;i<8;i++,in+=6,out+=4)
	{
		j=(in[0]<<1)+in[5];
		k=(in[1]<<3)+(in[2]<<2)+(in[3]<<1)+in[4];
		bytetobit(out,&s_box[i][j][k],4);
	}
}
void transform(bool *out,bool *in,const char *table,int len)
{
    static bool tmp[256];
	for(int i=0;i<len;i++)
		tmp[i]=in[table[i]-1];
	memcpy(out,tmp,len);
}
void xor(bool *ina,const bool *inb,int len)
{
	for(int i=0;i<len;i++)
		ina[i]^=inb[i];
}
void rotatel(bool *in,int len,int loop)
{
	static bool tmp[256];
	memcpy(tmp,in,loop);
	memcpy(in,in+loop,len-loop);
	memcpy(in+len-loop,tmp,loop);
}
 void bytetobit(bool *out,const char *in,int bits)
 {
	 for(int i=0;i<bits;i++)
		 out[i]=(in[i/8]>>(i%8))&1;
 }
void bittobyte(char *out,const bool *in,int bits)
{
	memset(out,0,(bits+7)/8);
	for(int i=0;i<bits;i++)
		out[i/8]|=in[i]<<(i%8);
}
void main()
{
    char key[8]={1,9,8,0,9,1,7,2},str[]="I am a girl!";
	printf("加密之前：");
	puts(str);
	des_setkey(key);
	des_run(str,str,encrypt);
	printf("加密以后：");
	printf("%s\n",str);
	des_run(str,str,decrypt);
    printf("解密以后：");
	printf("%s\n",str);
}