des3.cpp

加密算法,DES的C源码. 是分组算法,虽然现在用的少了 但还是有学习意仪的

// des3.cpp : Defines the entry point for the console application.
//
#include "stdafx.h"
#include "stdio.h"
#include <iostream.h>
#include <memory.h>
//////////////////////////////////////////////////////////////////////////

static void F_func(bool In[32], const bool Ki[48]);// F 函数
static void S_func(bool Out[32], const bool In[48]);// S 盒代替
static void Transform(bool *Out, bool *In, const char *Table, int len);// 变换
static void Xor(bool *InA, const bool *InB, int len);// 异或
static void RotateL(bool *In, int len, int loop);// 循环左移
static void ByteToBit(bool *Out, const char *In, int bits);// 字节组转换成位组
static void BitToByte(char *Out, const bool *In, int bits);// 位组转换成字节组

//////////////////////////////////////////////////////////////////////////

// 初始变换
const static 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
};
// 末置换
const static char IPR[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
};
// 扩展置换
static const char 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
};
// 作用在S盒的32位输出结果上的P变换 
const static char 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
};
// 密钥初始置换
const static char PC1[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
};
// 密钥压缩变换 PC-2 
const static char PC2[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
};
// 每圈移位次数 
const static char LOOP[16] = {
1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1
};
// S盒 
const static char S_Box[8][4][16] = {
// S1 
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,
// S2 
    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,
// S3 
    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,
// S4 
     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,
// S5 
     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,
// S6 
    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,
// S7 
     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,
// S8 
    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
};


static bool SubKey[16][48];// 16圈子密钥

void Des_Run(char Out[8], char In[8],int i)
{
    static bool M[64], Tmp[32], *Li = &M[0], *Ri = &M[32];
    ByteToBit(M, In, 64);// 字节组转换成位组
    Transform(M, M, IP, 64);// 初始变换
    if( i == 0 ){ //加密
        for(int i=0; i<16; i++) {
            memcpy(Tmp, Ri, 32);
            F_func(Ri, SubKey[i]);
            Xor(Ri, Li, 32);
            memcpy(Li, Tmp, 32);
        }
    }else{ //解密
        for(int i=15; i>=0; i--) {
            memcpy(Tmp, Li, 32);
            F_func(Li, SubKey[i]);
            Xor(Li, Ri, 32);
            memcpy(Ri, Tmp, 32);
        }
}
    Transform(M, M, IPR, 64);
    BitToByte(Out, M, 64);
}

void Des_SetKey(const char Key[8])    //设置密钥
{
    static bool K[64], *KL = &K[0], *KR = &K[28];
    ByteToBit(K, Key, 64);// 字节组转换成位组
    Transform(K, K, PC1, 56);// 密钥变换 PC-1
    for(int i=0; i<16; i++) {
        RotateL(KL, 28, LOOP[i]);
        RotateL(KR, 28, LOOP[i]);
        Transform(SubKey[i], K, PC2, 48);// 密钥压缩变换 PC-2 
    }
}
// F 函数
void F_func(bool In[32], const bool Ki[48])
{
    static bool MR[48];
    Transform(MR, In, E, 48);
    Xor(MR, Ki, 48);
    S_func(In, MR);
    Transform(In, In, P, 32);
}
// S 盒置换
void S_func(bool Out[32], const bool In[48])
{
    for(char i=0,j,k; i<8; i++,In+=6,Out+=4) {
        j = (In[0]<<1) + In[5];
        k = (In[1]<<3) + (In[2]<<2) + (In[3]<<1) + In[4];
ByteToBit(Out, &S_Box[i][j][k], 4);
    }
}
// 通用置换函数
void Transform(bool *Out, bool *In, const char *Table, int len)
{
    static bool Tmp[256];
    for(int i=0; i<len; i++)
        Tmp[i] = In[ Table[i]-1 ];
    memcpy(Out, Tmp, len);
}
// 异或运算
void Xor(bool *InA, const bool *InB, int len)
{
    for(int i=0; i<len; i++)
        InA[i] ^= InB[i];
}
// 循环左移
void RotateL(bool *In, int len, int loop)
{
    static bool Tmp[256];
    memcpy(Tmp, In, loop);//loop 为位移的个数
    memcpy(In, In+loop, len-loop);
    memcpy(In+len-loop, Tmp, loop);
}
// 字节转换成位
void ByteToBit(bool *Out, const char *In, int bits)
{
    for(int i=0; i<bits; i++)
        Out[i] = (In[i/8]>>(i%8)) & 1;
}
// 位转换成字节
void BitToByte(char *Out, const bool *In, int bits)
{
    memset(Out, 0, (bits+7)/8);
    for(int i=0; i<bits; i++)
        Out[i/8] |= In[i]<<(i%8);
}

void main(){
char key[8]={6,0,5,3,9,4,7},message[8];
cout<<"Please input The string before encrypting: \n";
cin>>message;

puts("Before encrypting");
puts(message);

Des_SetKey(key);

Des_Run(message, message, 0);
puts("After encrypting");
puts(message);

puts("After decrypting");
Des_Run(message, message, 1);
puts(message);
}