DES与3DES 加解密实例(c++)
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DES与3DES 加解密实例(c++)
DES原理:
DES算法是一种对称密码算法,也是一种分组加密的算法,以64位分组对数
据加密的,其密钥长度为64位,密钥事实上是56位参与DES运算(第8、16、24、
32、40、48、56、64位是校验位,使得每个密钥都有奇数个1),分组后的明文组和
56位的密钥按位替代或交换的方法形成密文组。
DES算法的主要流程如下图所示 。
1、 IP置换
IP置换目的是将输入的64位数据块按位重新组合,并把输出分为L0、R0两部分,
每部分各长32位
2、密码置换
DES的密钥由64位减至56位,每个字节的第8位作为奇偶校验位。产生的56位
密钥。在DES的每一轮中,从56位密钥循环左移再置换产生出不同的48位子密钥。
总共16轮,所以有16个子密钥。
4、E扩展置换
扩展置置换目标是IP置换后获得的右半部分R0,将32位输入扩展为48位(分为4
位×8组)输出。
扩展置换目的有两个:生成与密钥相同长度的数据以进行异或运算;提供更长的结
果,在后续的替代运算中可以进行压缩。
5、S盒代替
压缩后的密钥与扩展分组异或以后得到48位的数据,将这个数据送人S盒,进行替
代运算。替代由8个不同的S盒完成,每个S盒有6位输入4位输出。48位输入分
为8个6位的分组,一个分组对应一个S盒,对应的S盒对各组进行代替操作。
5、 P盒置换
S盒代替运算的32位输出按照P盒进行置换。该置换把输入的每位映射到输出位,
任何一位不能被映射两次,也不能被略去。
6、 IP-1末置换
末置换是初始置换的逆过程,DES最后一轮后,左、右两半部分并未进行交换,而是两部分合并形成一个分组做为末置换的输入
本代码实现了mp3加密过程,可以按照文件自行修改
#include <iostream>#include <stdio.h>#include "memory.h"#include <time.h>#include <stdlib.h>#define PLAIN_FILE_OPEN_ERROR -1#define KEY_FILE_OPEN_ERROR -2#define CIPHER_FILE_OPEN_ERROR -3#define OK 1///定义数据类型typedef char type;using namespace std;class Treble_DES{ ///初始置换表IP int 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}; ///逆初始置换表IP^-1 int IP_1[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}; ///扩充置换表E int 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}; //置换函数P int 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}; //S盒 int S[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}}}; //置换选择1 int PC_1[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}; //置换选择2 int PC_2[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, 50,44,32,46,43,48,38,55, 33,52,45,41,49,35,28,31}; //对左移次数的规定 int left[16] = {1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1}; ///字节转换成二进制 int ByteToBit(type ch, type bit[8]){ int cnt; for(cnt = 0;cnt < 8; cnt++){ *(bit+cnt) = (ch>>cnt)&1; } return 0; } ///二进制转换成字节 int BitToByte(type bit[8],type *ch){ int cnt; for(cnt = 0;cnt < 8; cnt++){ *ch |= *(bit + cnt)<<cnt; } return 0; } ///将长度为8的字符串转为二进制位串 int Char8ToBit64(type ch[8],type bit[64]){ int cnt; for(cnt = 0; cnt < 8; cnt++){ ByteToBit(*(ch+cnt),bit+(cnt<<3)); } return 0; } ///将二进制位串转为长度为8的字符串 int Bit64ToChar8(type bit[64],type ch[8]){ int cnt; memset(ch,0,8); for(cnt = 0; cnt < 8; cnt++){ BitToByte(bit+(cnt<<3),ch+cnt); } return 0; } ///生成子密钥 int DES_MakeSubKeys(type key[64],type subKeys[16][48]){ type temp[56]; int cnt; DES_PC1_Transform(key,temp);//PC1置换 for(cnt = 0; cnt < 16; cnt++){//16轮跌代,产生16个子密钥 DES_ROL(temp,left[cnt]);//循环左移 DES_PC2_Transform(temp,subKeys[cnt]);//PC2置换,产生子密钥 } return 0; } ///密钥置换pc1 int DES_PC1_Transform(type key[64], type tempbts[56]){ int cnt; for(cnt = 0; cnt < 56; cnt++){ tempbts[cnt] = key[PC_1[cnt]]; } return 0; } ///密钥置换pc2 int DES_PC2_Transform(type key[56], type tempbts[48]){ int cnt; for(cnt = 0; cnt < 48; cnt++){ tempbts[cnt] = key[PC_2[cnt]]; } return 0; } ///循环左移 int DES_ROL(type data[56], int time){ type temp[56]; //保存将要循环移动到右边的位 memcpy(temp,data,time); memcpy(temp+time,data+28,time); //前28位移动 memcpy(data,data+time,28-time); memcpy(data+28-time,temp,time); //后28位移动 memcpy(data+28,data+28+time,28-time); memcpy(data+56-time,temp+time,time); return 0; } ///IP置换 int DES_IP_Transform(type data[64]){ int cnt; type temp[64]; for(cnt = 0; cnt < 64; cnt++){ temp[cnt] = data[IP[cnt]]; } memcpy(data,temp,64); return 0; } ///IP逆置换 int DES_IP_1_Transform(type data[64]){ int cnt; type temp[64]; for(cnt = 0; cnt < 64; cnt++){ temp[cnt] = data[IP_1[cnt]]; } memcpy(data,temp,64); return 0; } ///扩展置换 int DES_E_Transform(type data[48]){ int cnt; type temp[48]; for(cnt = 0; cnt < 48; cnt++){ temp[cnt] = data[E[cnt]]; } memcpy(data,temp,48); return 0; } ///P置换 int DES_P_Transform(type data[32]){ int cnt; type temp[32]; for(cnt = 0; cnt < 32; cnt++){ temp[cnt] = data[P[cnt]]; } memcpy(data,temp,32); return 0; } ///异或 int DES_XOR(type R[48], type L[48] ,int count){ int cnt; for(cnt = 0; cnt < count; cnt++){ R[cnt] ^= L[cnt]; } return 0; } ///S盒置换 int DES_SBOX(type data[48]){ int cnt; int line,row,output; int cur1,cur2; for(cnt = 0; cnt < 8; cnt++){ cur1 = cnt*6; cur2 = cnt<<2; //计算在S盒中的行与列 line = (data[cur1]<<1) + data[cur1+5]; row = (data[cur1+1]<<3) + (data[cur1+2]<<2) + (data[cur1+3]<<1) + data[cur1+4]; output = S[cnt][line][row]; //化为2进制 data[cur2] = (output&0X08)>>3; data[cur2+1] = (output&0X04)>>2; data[cur2+2] = (output&0X02)>>1; data[cur2+3] = output&0x01; } return 0; } ///交换 int DES_Swap(type left[32], type right[32]){ type temp[32]; memcpy(temp,left,32); memcpy(left,right,32); memcpy(right,temp,32); return 0; } ///加密单个分组 int DES_EncryptBlock(type plainBlock[8], type subKeys[16][48], type cipherBlock[8]){ type plainBits[64]; type copyRight[48]; int cnt; Char8ToBit64(plainBlock,plainBits); //初始置换(IP置换) DES_IP_Transform(plainBits); //16轮迭代 for(cnt = 0; cnt < 16; cnt++){ memcpy(copyRight,plainBits+32,32); //将右半部分进行扩展置换,从32位扩展到48位 DES_E_Transform(copyRight); //将右半部分与子密钥进行异或操作 DES_XOR(copyRight,subKeys[cnt],48); //异或结果进入S盒,输出32位结果 DES_SBOX(copyRight); //P置换 DES_P_Transform(copyRight); //将明文左半部分与右半部分进行异或 DES_XOR(plainBits,copyRight,32); if(cnt != 15){ //最终完成左右部的交换 DES_Swap(plainBits,plainBits+32); } } //逆初始置换(IP^1置换) DES_IP_1_Transform(plainBits); Bit64ToChar8(plainBits,cipherBlock); return 0; } ///解密单个分组 int DES_DecryptBlock(type cipherBlock[8], type subKeys[16][48],type plainBlock[8]){ type cipherBits[64]; type copyRight[48]; int cnt; Char8ToBit64(cipherBlock,cipherBits); //初始置换(IP置换) DES_IP_Transform(cipherBits); //16轮迭代 for(cnt = 15; cnt >= 0; cnt--){ memcpy(copyRight,cipherBits+32,32); //将右半部分进行扩展置换,从32位扩展到48位 DES_E_Transform(copyRight); //将右半部分与子密钥进行异或操作 DES_XOR(copyRight,subKeys[cnt],48); //异或结果进入S盒,输出32位结果 DES_SBOX(copyRight); //P置换 DES_P_Transform(copyRight); //将明文左半部分与右半部分进行异或 DES_XOR(cipherBits,copyRight,32); if(cnt != 0){ //最终完成左右部的交换 DES_Swap(cipherBits,cipherBits+32); } } //逆初始置换(IP^1置换) DES_IP_1_Transform(cipherBits); Bit64ToChar8(cipherBits,plainBlock); return 0; } //加密文件 public: int treble_DES_Encrypt(char *plainFile, type *key_1,type *key_2,type *key_3,char *cipherFile){ FILE *plain, *cipher; int count; long fileLen; type plainBlock[8],cipherBlock1[8],cipherBlock2[8],cipherBlock3[8]; type Key1[64]; type Key2[64]; type Key3[64]; type subKeys1[16][48]; type subKeys2[16][48]; type subKeys3[16][48]; if((cipher = fopen(cipherFile,"wb")) == NULL){ return CIPHER_FILE_OPEN_ERROR; } if((plain = fopen(plainFile,"rb")) == NULL){ return PLAIN_FILE_OPEN_ERROR; } //设置密钥 //将密钥转换为二进制流 Char8ToBit64(key_1,Key1); Char8ToBit64(key_2,Key2); Char8ToBit64(key_3,Key3); //生成子密钥 DES_MakeSubKeys(Key1,subKeys1); DES_MakeSubKeys(Key2,subKeys2); DES_MakeSubKeys(Key3,subKeys3); //如果文件非空 while(!feof(plain)){ //每次读8个字节,并返回成功读取的字节数 if((count = fread(plainBlock,sizeof(char),8,plain)) == 8){ //3DES加密单组文件 DES_EncryptBlock(plainBlock,subKeys1,cipherBlock1); DES_DecryptBlock(cipherBlock1,subKeys2,cipherBlock2); DES_EncryptBlock(cipherBlock2,subKeys3,cipherBlock3); //写入 fwrite(cipherBlock3,sizeof(char),8,cipher); } } //补充最后一组 if(count){ //填充 memset(plainBlock + count,'\0',7 - count); //最后一个字符保存包括最后一个字符在内的所填充的字符数量 plainBlock[7] = 8 - count; //加密单个分组 DES_EncryptBlock(plainBlock,subKeys1,cipherBlock1); DES_DecryptBlock(cipherBlock1,subKeys2,cipherBlock2); DES_EncryptBlock(cipherBlock2,subKeys3,cipherBlock3); //写入文件 fwrite(cipherBlock3,sizeof(char),8,cipher); } fclose(plain); fclose(cipher); return OK; } //解密文件 public: int treble_DES_Decrypt(char *cipherFile, type *key_1,type *key_2,type *key_3,char *plainFile){ FILE *plain, *cipher; int count,times = 0; long fileLen; type plainBlock1[8],plainBlock2[8],plainBlock3[8],cipherBlock[8]; type Key1[64]; type Key2[64]; type Key3[64]; type subKeys1[16][48]; type subKeys2[16][48]; type subKeys3[16][48]; if((cipher = fopen(cipherFile,"rb")) == NULL){ return CIPHER_FILE_OPEN_ERROR; } if((plain = fopen(plainFile,"wb")) == NULL){ return PLAIN_FILE_OPEN_ERROR; } //将密钥转换为二进制流 Char8ToBit64(key_1,Key1); Char8ToBit64(key_2,Key2); Char8ToBit64(key_3,Key3); //生成子密钥 DES_MakeSubKeys(Key1,subKeys1); DES_MakeSubKeys(Key2,subKeys2); DES_MakeSubKeys(Key3,subKeys3); //取文件长度 fseek(cipher,0,SEEK_END); //将文件指针置尾 fileLen = ftell(cipher); //取文件指针当前位置 rewind(cipher); //将文件指针重指向文件头 while(1){ //密文的字节数一定是8的整数倍 fread(cipherBlock,sizeof(char),8,cipher); //3DES解密 DES_DecryptBlock(cipherBlock,subKeys3,plainBlock1); DES_EncryptBlock(plainBlock1,subKeys2,plainBlock2); DES_DecryptBlock(plainBlock2,subKeys1,plainBlock3); if(times < fileLen){ fwrite(plainBlock3,sizeof(char),8,plain); times += 8; } else{ break; } } //判断末尾是否被填充 if(plainBlock3[7] < 8){ for(count = 8 - plainBlock3[7]; count < 7; count++){ if(plainBlock3[count] != '\0'){ //3des DES_DecryptBlock(cipherBlock,subKeys3,plainBlock1); DES_EncryptBlock(plainBlock1,subKeys2,plainBlock2); DES_DecryptBlock(plainBlock2,subKeys1,plainBlock3); break; } } } if(count == 7){//有填充 fwrite(plainBlock3,sizeof(char),8 - plainBlock3[7],plain); } else{//无填充 fwrite(plainBlock3,sizeof(char),8,plain); } fclose(plain); fclose(cipher); return OK; }};int main(){ type key_1[8] = {'1','1','2','2','3','3','4','4'}; type key_2[8] = {'a','b','c','d','e','f','g','h'}; type key_3[8] = {'1','2','3','4','5','6','7','8'}; Treble_DES d; cout<<"开始加密"<<endl; cout<<d.treble_DES_Encrypt("1.mp3",key_1,key_2,key_3,"加密.txt"); cout<<"加密结束,开始解密"<<endl; cout<<d.treble_DES_Decrypt("加密.txt",key_1,key_2,key_3,"temp.mp3"); cout<<"解密完成"<<endl; getchar(); return 0;}
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