des.cpp

DES加密系统的C语言源代码 用C语言实现 欢迎下载

/********DES Encript by namgking********************************************/
/********compile on windows xp sp2,C-Free 3.5*****************************/
/********E-mail:  [e-mail]***************************************/
/********Author:   namgking*************************************************/
/********Note: if the code is of using,it's coded by namgking,*************/
/********or I don't know who did it!^_^************************************/
#include<stdio.h>
#include<string.h>
#include"des_encode.h"
int key[16][48];
char str[8];
void main()                 //main function
{
    EncodeMain();

}


void EncodeMain()           //EncodeMain function
{
  int i;

  char keychar[8];

  int key2[8];
  int strkey[8];


  printf("请输入8个要加密的字符：\n");
  for(i=0;i<8;i++)
     scanf("%c",&str[i]);
  getchar();
  for(i=0;i<8;i++)
    strkey[i]=str[i];
  printf("\n输入明文的十六进制为:\n");
  for(i=0;i<8;i++)
    printf("%10x",strkey[i]);
  printf("\n请输入密钥(8个字符):\n");
  for(i=0;i<8;i++)
     scanf("%c",&keychar[i]);
  for(i=0;i<8;i++)
     key2[i]=keychar[i];
  getchar();
   // printf("%c",keychar[i]);
  Encode(strkey,key2);
  printf("\n加密后十六进制密文是:\n");
  for(i=0;i<8;i++)
     printf("%10x",strkey[i]);
  printf("\n\n清输入解密密码\n");
  for(i=0;i<8;i++)
    scanf("%c",&keychar[i]);
  for(i=0;i<8;i++)
     key2[i]=keychar[i];
  Decode(strkey,key2);
  for(i=0;i<8;i++)
    printf("%10x",strkey[i]);
  for(i=0;i<8;i++)
    str[i]=strkey[i];
  printf("\n明文为：\t");
  for(i=0;i<8;i++)
    printf("%c",str[i]);
  printf("\n\n");

}


void keyBuild(int *keychar){            //create key array
    int i,j;
    int movebit[]={1,1,2,2,2,2,2,2,
                   1,2,2,2,2,2,2,1};
    int midkey2[56];
    int midkey[64];
    StrtoBin(midkey,keychar);
    for(i=0;i<56;i++)
      midkey2[i]=midkey[PC1[i]-1];
    for(i=0;i<16;i++)
      keyCreate(midkey2,movebit[i],i);
   }
void StrtoBin(int *midkey,int *keychar){     //change into binary
    int trans[8],i,j,k,n;
    n=0;
    for(i=0;i<8;i++){
        j=0;
        while(keychar[i]!=0){
            trans[j]=keychar[i]%2;
            keychar[i]=keychar[i]/2;
            j++;
        }
        for(k=j;k<8;k++)trans[k]=0;
        for(k=0;k<8;k++)
           midkey[n++]=trans[7-k];
    }
   }
void keyCreate(int *midkey2,int movebit,int n){
    int i,temp[4];
    temp[0]=midkey2[0];
    temp[1]=midkey2[1];
    temp[2]=midkey2[28];
    temp[3]=midkey2[29];
   if(movebit==2){
       for(i=0;i<26;i++){
         midkey2[i]=midkey2[i+2];
         midkey2[i+28]=midkey2[i+30];
       }
       midkey2[26]=temp[0];midkey2[27]=temp[1];
       midkey2[54]=temp[2];midkey2[55]=temp[3];  }
     else
     { for(i=0;i<27;i++){
        midkey2[i]=midkey2[i+1];
        midkey2[i+28]=midkey2[i+29];
       }
       midkey2[27]=temp[0];midkey2[55]=temp[2];
     }
    for(i=0;i<48;i++)
      key[n][i]=midkey2[PC2[i]-1];
}
void EncodeData(int *lData,int *rData,int *str){   //encodedata function
    int i,j,temp[8],lint,rint;//int h;
    int data[64];
    lint=0,rint=0;
    for(i=0;i<4;i++){
       j=0;
       while(str[i]!=0){
         temp[j]=str[i]%2;
         str[i]=str[i]/2;
         j++;
       }
       while(j<8)temp[j++]=0;
       for(j=0;j<8;j++)
        lData[lint++]=temp[7-j];
       j=0;
       while(str[i+4]!=0){
        temp[j]=str[i+4]%2;
        str[i+4]=str[i+4]/2;
        j++;
       }
       while(j<8)temp[j++]=0;
       for(j=0;j<8;j++)rData[rint++]=temp[7-j];
    }
    for(i=0;i<32;i++){
       data[i]=lData[i];
       data[i+32]=rData[i];
    }

    for(i=0;i<32;i++){
       lData[i]=data[IP1[i]-1];//printf("P1:%5d:%5d,%5d\n",IP1[i],lData[i],data[IP1[i]-1]);
       rData[i]=data[IP1[i+32]-1];
    }
    }
void F(int *rData,int *key){                   //F function
    int i,rDataP[48];
    Expand(rData,rDataP);


    for(i=0;i<48;i++){
      rDataP[i]=rDataP[i]^key[i];// printf("%10d",rDataP[i]);if((i+1)%6==0)printf("\n");
      }

    ExchangeS(rDataP,rData);

    ExchangeP(rData);


   }
void Expand(int *rData,int *rDataP){          //Expand function
    int i;
    for(i=0;i<48;i++)
      rDataP[i]=rData[Ex[i]-1];
   }
void ExchangeS(int *rDataP,int *rData){          //S-diagram change
    int i,n,linex,liney;
    linex=liney=0;
    for(i=0;i<48;i+=6){
        n=i/6; //printf("%10d\n",(rDataP[i]<<1));
        linex=(rDataP[i]<<1)+rDataP[i+5];
        liney=(rDataP[i+1]<<3)+(rDataP[i+2]<<2)+(rDataP[i+3]<<1)+rDataP[i+4];

        FillBin(rData,n,s[n][linex][liney]);
    }
   }
void ExchangeP(int *rData){                     //P change
    int i,temp[32];
    for(i=0;i<32;i++)
      temp[i]=rData[i];

    for(i=0;i<32;i++)
      rData[i]=temp[P[i]-1];
  }
void FillBin(int *rData,int n,int s){         // data to binary;call by S-Diagram change function
    int temp[4],i;
    for(i=0;i<4;i++){
        temp[i]=s%2;
        s=s/2;
        }
    for(i=0;i<4;i++)
        rData[n*4+i]=temp[3-i];
    }
void DecodeData(int *str,int *lData,int *rData){    //DecodeData from binary
    int i;int a,b;int data[64];
    a=0,b=0;
    for(i=0;i<32;i++){
        data[i]=lData[i];
        data[i+32]=rData[i];
    }
    for(i=0;i<32;i++){
        lData[i]=data[IP2[i]-1];
        rData[i]=data[IP2[i+32]-1];
    }
    for(i=0;i<32;i++){
        a=(lData[i]&0x1)+(a<<1);
        b=(rData[i]&0x1)+(b<<1);
        if((i+1)%8==0){
            str[i/8]=a;a=0;//printf("%d",i/8);
            str[i/8+4]=b;b=0;//printf("%d",i/8+4);
        }
    }

    }
   
void Encode(int *str,int *keychar){           //encode: input 8 chars,8 keychars
   int lData[32],rData[32],temp[32],rDataP[48];
   int i,j;
   keyBuild(keychar);

   EncodeData(lData,rData,str);
   for(i=0;i<16;i++){
     for(j=0;j<32;j++)
        temp[j]=rData[j];
     F(rData,key[i]);
     for(j=0;j<32;j++){
        rData[j]=rData[j]^lData[j];
     }

     for(j=0;j<32;j++)
        lData[j]=temp[j];
   }

   DecodeData(str,rData,lData);

}
void Decode(int *str,int *keychar){           //decode :input 8 chars,8 keychars
   int lData[32],rData[32],temp[32],rDataP[48];
   int i,j;
   keyBuild(keychar);
   EncodeData(lData,rData,str); //这个位置
   for(i=0;i<16;i++){
     for(j=0;j<32;j++)
        temp[j]=rData[j];
     F(rData,key[15-i]);
     for(j=0;j<32;j++){
        rData[j]=rData[j]^lData[j];
     }

     for(j=0;j<32;j++){
        lData[j]=temp[j];
        }
   }
   DecodeData(str,rData,lData);
}