main.c

DES的C实现 用 gcc 3.4.2编译通过

#include <stdio.h>
#include <string.h>
#include <memory.h>

/*密钥置换选择表PC_1*/
const char 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

};

/*左移循环表Left_loop*/
const char Left_loop[16]={
	1,1,2,2,2,2,2,2,1, 2, 2, 2, 2, 2, 2,1

};

/*密钥置换选择表PC_2*/
const char 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
};

/*数据初始变换表*/
const char IP[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

};

/*扩展表*/
const char Exp[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
};

/*S_Box*/
const static char S[8][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,
	 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,
    
	 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,
   
    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
  };

/*把从S盒中得到的数据重新排列的表*/
const char PP[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
};
    
/*逆IP置换*/
const char FP[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
    
};

/* 密钥定义*/
static unsigned char DesKey[8];
static unsigned char SubKey[16][48];
static unsigned char tmp[128];

void trans_table(char * Out ,char * In ,  const char * Table , int len)
{
    int i;
	for(i=0;i!=len;i++)
	     tmp[i]=In[Table[i]-1];
	memcpy(Out , tmp , len);
}


void Bytes_to_Bits(unsigned char * Out , const unsigned char * In , int len)
{
    int i;
    for(i=0;i!=len;i++)
	{
	    
        Out[i]=(In[i>>3]>>(i&7)) & 1;		
	    
	}
}

void Bits_to_Bytes(unsigned char * Out , const unsigned char * In , int len)
{
     int i;
	 memset(Out, 0,len>>3);
	 for(i=0;i!=len;i++)
	 {
	     Out[i>>3] |= (In[i]<<(i&7));
	 }
}

void Xor(unsigned char * Out , unsigned char * In , int len)
{
     int i;
	 for(i=0;i!=len;i++)
	 if(Out[i]!=In[i]) Out[i]=1;
	 else Out[i]=0;

}

void Rotate(unsigned char * In , int len , int loop)
{  
   memcpy(tmp,In,loop);
   memcpy(In,In+loop,loop);
   memcpy(In+len-loop,tmp,loop);
}

void Set_Subkey(unsigned char * key)
{
    int i=strlen(key);
	if(i>8)
	memcpy(DesKey,key,8);
	else
	{
	   memset(DesKey,0,8);
	   memcpy(DesKey,key,i);
	}
	char tk[64];
	Bytes_to_Bits(tk,DesKey,64);
	trans_table(tk,tk,PC_1,56);
	char C[2],D[2];
	for(i=0;i!=16;i++)
	{
	   Rotate(&tk[0],28,Left_loop[i]);
	   Rotate(&tk[28],28,Left_loop[i]);
	   trans_table(SubKey[i],tk,PC_2,48);
	}
}

void S_func(unsigned char E[48],unsigned char B[32])
{
    int i,j,k;
	for(i=0;i!=8;i++,E+=6,B+=4)
	{
	   
	    j=(E[0]<<1)+E[5];
		k=(E[1]<<3)+(E[2]<<2)+(E[3]<<1)+E[4];
		Bytes_to_Bits(B,&S[i][j][k],4);
	}
}

void F_func(unsigned char RL[32], char unsigned key[48] ,unsigned char B[32])
{
	unsigned char E[48];
	trans_table(E,RL,Exp,48);
	Xor(E,key,48);
    S_func(E,B);
    trans_table(B,B,PP,32);
}

void Des_E(unsigned char In[8] , unsigned char Out[8] )
{
    unsigned char tt[64],B[32] , * L=&tt[0] , *R=&tt[32] ;
	int i;
	Bytes_to_Bits(tt,In,64);
	trans_table(tt,tt,IP,64);
	for(i=0;i!=16;i++)
	{
		F_func(R,SubKey[i],B);
		Xor(B,L,32);
		memcpy(L,R,32);
		memcpy(R,B,32);
	}
	trans_table(tt,tt,FP,64);
	Bits_to_Bytes(Out,tt,64);

}

void Des_D(unsigned char In[8] , unsigned char Out[8] )
{
    unsigned char tt[64],B[32],*L=&tt[0],*R=&tt[32];
	int i;
	Bytes_to_Bits(tt,In,64);
	trans_table(tt,tt,IP,64);
	for(i=15;i>=0;i--)
	{
		F_func(L,SubKey[i],B);
		Xor(B,R,32);
		memcpy(R,L,32);
		memcpy(L,B,32);
	}
	trans_table(tt,tt,FP,64);
	Bits_to_Bytes(Out,tt,64);

}

int main()
{
	int i,j,len;
    unsigned char key[16];
    printf("请输入密钥（8位）:");
	scanf("%s",&key);
	printf("%s\n",key);
    Set_Subkey(key);
	unsigned char In[128];
	unsigned char Out[128];
	unsigned char D_Out[128];
	memset(In,0,128);
	memset(Out,0,128);
	printf("请输入要加密的内容（100位以内）:\n");
	scanf("%s",In);
	len=strlen(In);
	printf("\n输入字符串长为:  %d\n",len);
	j=len>>3;
	for(i=0;i!=j+1;i++)
	{
	    Des_E(In+(i*8),Out+(i*8));
	}
	printf("加密结果用ASCII码形式表示为:\n");
	for(i=0;i!=len>>3;i++)
	{
	    for(j=0;j!=8;j++)
      	    printf("%c  ",Out[(i<<3)+j]);
		printf("\n");
    }
    for(i=(len>>3)<<3;i!=len;i++)
        printf("%c ",Out[i]);
    printf("\n");
    printf("\n");
    printf("加密结果用二进制形式表示为:\n");
    for(i=0;i!=len>>2;i++)
	{
        Bytes_to_Bits(tmp,Out+(i<<2),32);
	    for(j=0;j!=32;j++)
	    {
            
      	    printf("%d ",tmp[j]);
        }
		printf("\n");
    }

    for(i=(len>>3)<<3;i!=len;i++)
    {
        Bytes_to_Bits(tmp,Out+i,8);
	    for(j=0;j!=8;j++)
	    {
            
      	    printf("%d ",tmp[j]);
        }
    }
    printf("\n");
    printf("\n");
    printf("加密结果用十六进制形式表示为:\n");
   	for(i=0;i!=(len>>3);i++)
	{
	    for(j=0;j!=8;j++)
	    printf("%2x ",Out[(i<<3)+j]);
		printf("\n");
	}
    for(i=(len>>3)<<3;i!=len;i++)
        printf("%2x ",Out[i]);
    printf("\n\n");
    printf("解密后结果为:\n");
	for(i=0;i!=j+1;i++)
	{
	    Des_D(Out+(i*8),D_Out+(i*8));
	}
	for(i=0;i!=len;i++)
	    printf("%c ",D_Out[i]);
	printf("\n\n\n");
	
	return 0;
}