des.cpp

des加密算法 des加密算法 des加密算法 解密

#include<stdio.h>
#include<string.h>
#include<math.h>	
static int ip_tab[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};
static int _ip_tab[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};
static int pc_1[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};
static int pc_2[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};
static int ls[16]={1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1};
static int E[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};

static int _p[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};
static int SSS[16][4][16]={
	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,/* err on */
	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,

	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,

	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,

	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, /* err on */

	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, /* err on */
	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,

	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,

	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,

	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 key[16][48]={0},plaint[64],cipher[64],c[28]={0},d[28]={0},
		L[17][32],R[17][32];
void p(int a[],int n1,int n2,int symbol)          //其中n1是置换前的位数，n2是置换后的位数。
{
	int i,b[100]={0};
	for(i=0;i<n1;i++)
		b[i]=a[i];
	if(symbol)
	{
		if(n2==64)
		{
			for(i=0;i<n2;i++)
				a[i]=b[ip_tab[i]-1];
		}
		if(n2==56)
			for(i=0;i<n2;i++)
				a[i]=b[pc_1[i]-1];
		if(n2==48)
		{
			if(n1==56)
				for(i=0;i<n2;i++)
					a[i]=b[pc_2[i]-1];
			else
				for(i=0;i<n2;i++)
					a[i]=b[E[i]-1];
		}
		if(n2==32)
			for(i=0;i<n2;i++)
				a[i]=b[_p[i]-1];
	}
	else                            //逆变换过程
		if(n2==64)
		{
			for(i=0;i<n2;i++)
				a[i]=b[_ip_tab[i]-1];
		}
}
void Ls(int n)
{
	int buf[28]={0},i;
	for(i=0;i<28;i++)
		buf[i]=c[i];
	for(i=0;i<28;i++)
		c[i]=buf[(i+ls[n])%28];
	for(i=0;i<28;i++)
		buf[i]=d[i];
	for(i=0;i<28;i++)
		d[i]=buf[(i+ls[n])%28];
}
	
void sub_key(char * s)                  //生成16轮的子密钥
{
	int times,i,j=0,m,g;
	int k[64];                   //k0二进制密钥
	for(i=0;i<16;i++)
	{
		times=8;
		m=s[i]-'0';
		if(m>9)
			m=m-7;
		while(times)
		{
			k[j++]=m/times;m%=times;
			times/=2;
		}
	}
	
   p(k,64,56,1);
   for(i=0;i<28;i++)
	   c[i]=k[i];
   for(;i<56;i++)
	   d[i-28]=k[i];
   for(j=0;j<16;j++)
   {
	   Ls(j);
	   for(i=0;i<28;i++)
		   key[j][i]=c[i];
	   for(;i<56;i++)
		   key[j][i]=d[i-28];
	   p(key[j],56,48,1);
   }
}
void x_or(int a[],int b[],int n)
{
	int i;
	for(i=0;i<n;i++)
		a[i]=(a[i]+b[i])%2;
}

void itox(int a[],int i,int j,int n)
{
	int times=(int)pow(2,j-1);
	while(times)
	{
		a[i++]=n/times;n%=times;times/=2;
	}
}
void place_s(int a[],int n)
{
	int x,y,z,i,m,b[32]={0};
	for(x=0;x<8;x++)
	{
		i=x*6;
		y=a[i]*2+a[i+5];
		z=a[i+1]*8+a[i+2]*4+a[i+3]*2+a[i+4];
		m=SSS[x][y][z];
		itox(b,x*4,4,m);
	}
	for(i=0;i<32;i++)
		a[i]=b[i];
}


		
void Ffunction(int f,int symb)
{
	int i,j;
	if(symb==1)
		j=f;
	else
		j=15-f;
	for(i=0;i<32;i++)
		L[f+1][i]=R[f][i];
	p(R[f],32,48,1);
	x_or(R[f],key[j],48);
	place_s(R[f],48);                      //S盒替换
	p(R[f],48,32,1);
	x_or(L[f],R[f],32);
	for(i=0;i<32;i++)
		R[f+1][i]=L[f][i];
}


void Desciption(char c)
{
	int i,j;
	if(c=='e')                              //加密跟解密所用的密钥顺序不一样，所以分开进行
	{
		p(plaint,64,64,1);
		for(i=0;i<32;i++)
			L[0][i]=plaint[i];
		for(;i<64;i++)
			R[0][i-32]=plaint[i];
		for(j=0;j<16;j++)
			Ffunction(j,1);                   //其中1用来区别加密和解密中所用的密钥顺序
		for(i=0;i<32;i++)
			cipher[i]=R[16][i];
		for(;i<64;i++)
			cipher[i]=L[16][i-32];
		p(cipher,64,64,0);         //逆初始置换
	}
	else
	{ 
		p(cipher,64,64,1);
		for(i=0;i<32;i++)
			L[0][i]=cipher[i];
		for(;i<64;i++)
			R[0][i-32]=cipher[i];
		for(j=0;j<16;j++)
			Ffunction(j,0);                   //其中1用来区别加密和解密中所用的密钥顺序
		for(i=0;i<32;i++)
			plaint[i]=R[16][i];
		for(;i<64;i++)
			plaint[i]=L[16][i-32];
		p(plaint,64,64,0);         //逆初始置换
	}
}



int main()
{
	int i=0,j,m,times=128;
	char keys[17],message[9],ch;
	printf("Input Key:");
	gets(keys);
	printf("Input PlainText:");
	//getchar();
	for(i=0;i<8;i++)              //将字符转化为二进制数
	{
		m=getchar();
		j=i*8;
		times=128;
		while(times)
		{
			plaint[j++]=m/times;
			m%=times;
			times/=2;
		}
	}
//	getchar();
	sub_key(keys);
	Desciption('e');                   //Desciption加密
	printf("CipherText:");i=0;
    while(i<16)                //输出加密后十六进制数cipher
	{
		j=i*4;
		m=cipher[j]*8+cipher[j+1]*4+cipher[j+2]*2+cipher[j+3];
        if(m>9)
			m+=7;
		ch=m+'0';
		putchar(ch);i++;
	}
	putchar('\n');
    Desciption('d');                 //Desciption解密
	printf("Decryption:");
	i=0;
   while(i<8)
   {
	j=i*8;
	m=plaint[j+0]*128+plaint[j+1]*64+plaint[j+2]*32+plaint[j+3]*16+plaint[j+4]*8+plaint[j+5]*4+plaint[j+6]*2+plaint[j+7];
    putchar(m);
	i++;
   }
   putchar('\n');

	return 0;
}