encryption.cpp

用DES加密算法实现文件的加密和解密

// Encryption.cpp: implementation of the CEncryption class.
//
//////////////////////////////////////////////////////////////////////

#include "stdafx.h"
#include "FileEncryption.h"
#include "Encryption.h"

#ifdef _DEBUG
#undef THIS_FILE
static char THIS_FILE[]=__FILE__;
#define new DEBUG_NEW
#endif


 int IP[65]={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,
	            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}; 

   int Extend[49]={0,32,1,2,3,4,5,
	           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};
   int Replace[33]={0,16,7,20,21,
	           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};
   int IP_1[65]={0,40,8,48,16,56,24,64,32,
	              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};
   	int s1[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};
    int s2[4][16]={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};
	int s3[4][16]={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};
	int s4[4][16]={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};
	int s5[4][16]={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};
	int s6[4][16]={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};
	int s7[4][16]={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};
	int s8[4][16]={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[57]={0,57,49,41,33,25,17,9,
	              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};
	int PC_2[49]={0,14,17,11,24,1,5,
                  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};
	int shift[17]={0,1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1};

//////////////////////////////////////////////////////////////////////
// Construction/Destruction
//////////////////////////////////////////////////////////////////////

CEncryption::CEncryption()
{

}

CEncryption::~CEncryption()
{

}

bool CEncryption::desEncryption()
{
    init();
	int RExtend[49];int temp[33];
    int f[33],f_1[33];int temp_1[5]; int miwen1[65];
    int	s11[7],s21[7],s31[7],s41[7],s51[7],s61[7],s71[7],s81[7];
	int s[9];
    for(int a=1;a<=16;a++)
	{
       for(int i=1;i<=48;i++)//经过Extend变换扩充，由32位变为48位
	   RExtend[i]=R0[Extend[i]];
	   if(isEncryption)
	   {
		   for(int i=1;i<=48;i++)//与K按位作不进位加法运算
			   RExtend[i]=xor(RExtend[i],k[a-1][i]);
	   }
	   else
	   {
		   for(int  i=1;i<=48;i++)
			   RExtend[i]=xor(RExtend[i],k[16-a][i]);
	   } 
       for(i=1;i<=6;i++)
	   {
          s11[i]=RExtend[i];
		  s21[i]=RExtend[6+i];
		  s31[i]=RExtend[12+i];
          s41[i]=RExtend[18+i];
		  s51[i]=RExtend[24+i];
		  s61[i]=RExtend[30+i];
		  s71[i]=RExtend[36+i];
		  s81[i]=RExtend[42+i];
	   }
	   //经过s盒运算后
       	s[1]=s1[s11[6]+s11[1]*2][s11[5]+s11[4]*2+s11[3]*4+s11[2]*8];//注:行列从零开始 
	    s[2]=s2[s21[6]+s21[1]*2][s21[5]+s21[4]*2+s21[3]*4+s21[2]*8];
	    s[3]=s3[s31[6]+s31[1]*2][s31[5]+s31[4]*2+s31[3]*4+s31[2]*8];
	    s[4]=s4[s41[6]+s41[1]*2][s41[5]+s41[4]*2+s41[3]*4+s41[2]*8];
	    s[5]=s5[s51[6]+s51[1]*2][s51[5]+s51[4]*2+s51[3]*4+s51[2]*8];
	    s[6]=s6[s61[6]+s61[1]*2][s61[5]+s61[4]*2+s61[3]*4+s61[2]*8];
	    s[7]=s7[s71[6]+s71[1]*2][s71[5]+s71[4]*2+s71[3]*4+s71[2]*8];
	    s[8]=s8[s81[6]+s81[1]*2][s81[5]+s81[4]*2+s81[3]*4+s81[2]*8];
		for(i=1;i<=8;i++)//8个数变换输出二进制
		{
			for(int j=1;j<5;j++)
			{
				temp_1[j]=s[i]%2;
				s[i]=s[i]/2;
			}
			for(j=1;j<5;j++)
				f[4*(i-1)+j]=temp_1[5-j];
		}
		for(i=1;i<=32;i++)
		{
			f_1[i]=f[Replace[i]];
		}
		
		
		for( i=1;i<=32;i++)
			temp[i]=xor(L0[i],f_1[i]);
		
		for(i=1;i<=32;i++)
		{L0[i]=R0[i];R0[i]=temp[i];}

	}
    for(int i=1;i<=32;i++)
	{
		miwen1[i]=R0[i];
		miwen1[i+32]=L0[i];
	}
	for(i=1;i<=64;i++)   //最后进行一次IP逆变换
	{miwen[i]=miwen1[IP_1[i]];}
    
	return true;
}

CEncryption::CEncryption(int minwen[], int key[],bool isEncryption)
{
	for(int i=0;i<=64;i++)
	{
		this->minwen[i]=minwen[i];
		this->key[i]=key[i];
	}
	   this->isEncryption=isEncryption;
     
}

void CEncryption::init()
{
	int  minwen1[65];
	for(int i=1;i<65;i++)
		minwen1[i]=minwen[IP[i]];
	for(i=1;i<33;i++)
	  L0[i]=minwen1[i];//明文左侧的初始化
	for(i=33;i<=64;i++)
      R0[i-32]=minwen1[i];//明文右侧的初始化

	//生成子密钥
	int k0[57];int C[29],D[29],C1[29],D1[29];int whole[57]; bool flag=true;
    for(i=1;i<57;i++)
	  k0[i]=key[PC_1[i]];//变换选择1
    for(i=1;i<29;i++)
	  C[i]=k0[i];
	for(i=29;i<=56;i++)
	  D[i-28]=k0[i];

	for(int a=1;a<=16;a++)//产生16个子密钥
	{
        if(flag)
		{
			int i,j;
			for( i=1;i+shift[a]<29;i++)
			{
				C1[i]=C[i+shift[a]];
				D1[i]=D[i+shift[a]];
			}
			for(i=shift[a],j=1;i>0;i--,j++)
			{	C1[29-i]=C[j];D1[29-i]=D[j];}//循环移位
            for(i=1;i<=28;i++)
			{whole[i]=C1[i];whole[28+i]=D1[i];}//拼接 
			for(i=1;i<=48;i++)
			{
				k[a-1][i]=whole[PC_2[i]];
			}
			flag=false;
		}
		else
		{
			int i,j;
			for(i=1;i+shift[a]<29;i++)
			{
				C[i]=C1[i+shift[a]];
				D[i]=D1[i+shift[a]];
			}
			for(i=shift[a],j=1;i>0;i--,j++)
			{	C[29-i]=C1[j];D[29-i]=D1[j];}
            for(i=1;i<=28;i++)
			{whole[i]=C[i];whole[28+i]=D[i];}
			for( i=1;i<=48;i++)
			{
				k[a-1][i]=whole[PC_2[i]];
			}
            flag=true;
		}       
	}
}

int CEncryption::xor(int a, int b)
{
    if(a==b)
		return 0;
	else
		return 1;
}