信息安全試驗-DES加密！

                                         信息安全試驗二——DES加密算法

   本渣表示沒有理解原理，照着書上敲了一發，運行無誤！

   吐槽：手動S盒簡直喪心病狂，擴展置換表全是手動輸入，加密原理仍是很好理解，兩次異或，先混淆。

   此代碼數據由老師給出，r[]與k[]數組可變。

#include<bits/stdc++.h>
using namespace std;
const int N=100+10;
int r[N]= {1,0,0,0,0,0,  0,0,0,0,0,1,  0,1,1,1,1,1,  1,1,1,1,1,0,
           1,0,0,0,0,0,  0,0,1,1,0,1,  0,1,0,0,0,0,  0,0,0,1,1,0
          };//E擴展直接由表寫出
int k[N]= {1,1,1,1,0,0,  0,0,1,0,1,1,  1,1,1,0,0,1,  1,0,1,1,1,0,
           0,1,1,1,0,1,  0,1,0,0,1,0,  1,0,0,0,0,0,  1,1,0,0,0,0
          };
int a[N];//祕鑰加的結果
int len=0,s_boox[N];//s盒代換結果
int ans[N];//p置換後的結果
void ch(int tmp)
{
    int temp[6],l=0;
    while(tmp)
    {
        temp[l++]=tmp%2;
        tmp/=2;
    }
    for(int i=l-1; i>=0; i--) s_boox[len++]=temp[i];
}
void add()//祕鑰加
{
    for(int i=0; i<48; i++)  a[i]=r[i]^k[i];
}
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},{4,3,2,13,9,5,15,10,11,14,1,7,6,0,8,13}};
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 P[100]= {16,7,20,21,2,8,24,14,29,12,28,17,32,27,3,9,1,15,23,26,19,13,30,6,5,18,31,10,22,11,4,25};
void s_box()
{
    len=0;
    int f=1;
    for(int i=0; i<48; i+=6,f++)
    {
        int x=0,r=(a[i]==1?2:0)+(a[i+5]==1?1:0);//行
        int c=(a[i+1]==1?8:0)+(a[i+2]==1?4:0)+(a[i+3]==1?2:0)+(a[i+4]==1?1:0);//列
        if(f==1)  x=s1[r][c];
        if(f==2)  x=s2[r][c];
        if(f==3)  x=s3[r][c];
        if(f==4)  x=s4[r][c];
        if(f==5)  x=s5[r][c];
        if(f==6)  x=s6[r][c];
        if(f==7)  x=s7[r][c];
        if(f==8)  x=s8[r][c];
        ch(x);
    }
}
void P_zhihuan()
{
    for(int i=0; i<32; i++) ans[i]=s_boox[P[i]];
}
void work()//實際上調用不少函數很費時間
{
    add();
    s_box();
    P_zhihuan();r
    printf("加密結果：");
    for(int tt=1,i=0; i<32; i++,tt++) //32bit
    {
        printf("%d",ans[i]);
        if(tt==4)
        {
            printf(" ");
            tt=0;
        }
    }
}
void happy()
{
    puts("\n           What does the fox say?");
    puts("Hatee-hatee-hatee-ho!");
    puts("Joff-tchoff-tchoffo-tchoffo-tchoff!");
}
int main()
{
    work();
    happy();
}