des_ecbmode.cpp

利用DES算法（包括ECB和CBC模式）加解密BMP图像

//DES ECB模式 修改版 处理BMP文件头部信息部分从DES加密函数中剥离
#include <iostream>
#include <vector>
#include <stdio.h>
#include <math.h>
#include <errno.h>
#include "windows.h"
using namespace std;

static unsigned char
        PC1[56] = {56, 48, 40, 32, 24, 16, 8,
                0, 57, 49, 41, 33, 25, 17,
                9, 1, 58, 50, 42, 34, 26,
                18, 10, 2, 59, 51, 43, 35,
                62, 54, 46, 38, 30, 22, 14,
                6, 61, 53, 45, 37, 29, 21,
                13, 5, 60, 52, 44, 36, 28,
                20, 12, 4, 27, 19, 11, 3},              //PC-1 将64位秘钥转为56位(去掉校验位)
        shift[16] = {1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1}, //移位次数
        PC2[48] = {13, 16, 10, 23, 0, 4,
                2, 27, 14, 5, 20, 9,
                22, 18, 11, 3, 25, 7,
                15, 6, 26, 19, 12, 1,
                40, 51, 30, 36, 46, 54,
                29, 39, 50, 44, 32, 47,
                43, 48, 38, 55, 33, 52,
                45, 41, 49, 35, 28, 31 },               //PC-2 56位秘钥压缩到48位
        IP[64] = {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,
                56, 48, 40, 32, 24, 16, 8, 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},         //初始置换IP
        E[48] = {31, 0, 1, 2, 3, 4,
                3, 4, 5, 6, 7, 8,
                7, 8, 9, 10, 11, 12,
                11, 12, 13, 14, 15, 16,
                15, 16, 17, 18, 19, 20,
                19, 20, 21, 22, 23, 24,
                23, 24, 25, 26, 27, 28,
                27, 28, 29, 30, 31, 0 },                //E Bit-Selection Table
        //S盒
        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},
        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},
        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 },
        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 },
        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 },
        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 },
        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 },
        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 },

        P[32] = {15, 6, 19, 20,
                28, 11, 27, 16,
                0, 14, 22, 25,
                4, 17, 30, 9,
                1, 7, 23, 13,
                31, 26, 2, 8,
                18, 12, 29, 5,
                21, 10, 3, 24 },                //置换P
        IP_inverse[64] = {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,
                32, 0, 40, 8, 48, 16, 56, 24};  //IP的逆置换

void lrotate(char *array, int length, int count)
//将array数组(length个元素)循环左移count次
{
        vector<char> temp;
        temp.resize(length);
        for(int i=0; i<length-count; i++)
                temp[i] = array[i + count];

        for(int i=0; i<count; i++){
                temp[length-count+i] = array[i];
        }

        for(int i=0; i<length; i++){
               // cout << int(temp[i]);
                array[i] = temp[i];
        }
}

class DES
{
        private:
                int subKeys[17][48];            //16个子密钥
                int readBMP(FILE *bmp, char *strBuf);   //从BMP文件中一次读出8个字节信息到buf中
                void writeBMP(FILE *bmp, char *str, int nobj);//将64个元素的数组转化成nobj字节信息写到BMP文件中
        public:
                DES(char* skey);                //构造函数，用于生成密钥
                void printKey();
                void cryptography(FILE* fin, FILE* fout, int mode); //加\解密函数, 0为加密 1为解密
};

DES::DES(char* skey)
{
        char key[64], key_without_check[56],    //原始密钥、去掉校验位的密钥
                C[17][28], D[17][28], CD[17][56];       //密钥的左右两部分
        int i=0;

        //============================密钥处理部分==============================
        //8字节密钥转为64位的字符数组
        while(*skey != NULL){
                char character = *skey;
                for(int j=128, s=7; j>=1; j=j/2, s--)
                        key[i++] = (character & j) >> s;
                skey++;
        }

        //利用PC1去掉奇偶校验位 密钥变为56位
        for(i = 0; i<56; i++)
                key_without_check[i] = key[PC1[i]];
        //=============
        //for(i = 0; i<56; i++)
        //        cout << int(key_without_check[i]);
        //=============

        //分成左右两部分 得到Ｃ０, Ｄ０
        for(i=0; i<28; i++){
                C[0][i] = key_without_check[i];
                D[0][i] = key_without_check[i+28];
        }

        //循环左移，得到C1-C16, D1-D16
        for(i=1; i<=16; i++){
                for(int j=0; j<28; j++){
                        C[i][j] = C[i-1][j];
                        D[i][j] = D[i-1][j];
                }
                //左移
                lrotate(C[i], 28, shift[i-1]);
                lrotate(D[i], 28, shift[i-1]);
        }

        //使用PC2压缩密钥 56位密钥变为48位 至此，得到最终16个子密钥subKeys
        for(i=1; i<=16; i++)
                for(int j=0; j<28; j++){
                        CD[i][j] = C[i][j];
                        CD[i][j+28] = D[i][j];
                }
        for(i=1; i<=16; i++){
                for(int j=0; j<48; j++){
                        subKeys[i][j] = CD[i][PC2[j]];
                        //输出检查=========
                        //cout << int(subKeys[i][j]);
                        //=================
                }
                //cout << "\n";
        }

        //OK====================================================================
}

void DES::printKey()
{
     for(int i=1; i<=16; i++){
                for(int j=0; j<48; j++)
                        cout << subKeys[i][j];
                cout << "\n";
     }
}

int DES::readBMP(FILE *bmp, char *strBuf)
//从BMP文件中一次读出8个字节信息到buf中 不足8个字节部分补零 返回实际读入的字节数
{
        int nobj;

        //如果文件已经结束
        if( feof(bmp) != 0 ){
                return -1;
        }
        //如果文件未结束
        else{
                nobj = fread(strBuf, sizeof(char), 8, bmp);
                //不足64字节部分补零
                if(nobj < 8){
                       for(int i=nobj; i<8; i++)
                               strBuf[i] = 0;