C++实现DES加密解密

DES实验要求

实验目的

实现电子本模式（ECB）和密码分组链接模式（CBC）的DES算法。

实验要求

1. 指定明文文件、密钥文件、初始化向量文件的位置和名称，加密的操作模式以及加密完成后密文文件的位置和名称。
2. 加密时先分别从指定的明文文件、密钥文件和初始化向量文件中读取有关信息，然后按ECB和CBC操作模式分别进行加密，最后将密文（用16进制表示）写入指定的密文文件。解密类似。
3. 统一将文件名命名如下：
   明文文件名：des_messages.txt
   密钥文件名：des_key.txt
   密文文件名：des_secret.txt
   解密结果文件名：des_decrypted.txt
   初始化向量文件：des_iv.txt
4. 如果一个分组不足64bit，低位补0。

代码

DES.h

#ifndef DESH
#define DESH
#include <string>
using namespace std;

/*DES.h: declaration of the TDES、TBase64、TBase64DES class. */
/* TDES类说明：该类是DES和3DES算法类 */
class CDES {
   
public:
	CDES();
	virtual ~CDES();
	static char* HexToStr(string s);
	static string StrToHex(char* bytes, int bytelength);
	
	static bool EnCode();  //des加密
	static bool DeCode(); //des解密
protected:
	typedef bool(*PSubKey)[16][48];
	
	//计算并填充子密钥到SubKey数据中  
	static void SetSubKey(PSubKey pSubKey, const unsigned char Key[8]);
	
	//DES单元运算  
	static void DES(unsigned char Out[8], const unsigned char In[8], const PSubKey pSubKey, bool Type);
	
	/* 补足8位数据
	* Description: 根据协议对加密前的数据进行填充
	* @param nType: 类型：PAD类型
	* @param In: 数据串指针
	* @param Out: 填充输出串指针
	* @param datalen: 数据的长度
	* @param padlen: (in,out)输出buffer的长度，填充后的长度
	* @return true--成功；false--失败；
	*/
	static bool RunPad(bool bType, int nType, const unsigned char* In, unsigned datalen, unsigned char* Out, unsigned& padlen);
	
	/* 执行DES算法对文本加解密
	* Description    : 执行DES算法对文本加解密
	* @param bType   : 类型：加密ENCRYPT，解密DECRYPT
	* @param bMode   : 模式：ECB,CBC
	* @param In      : 待加密串指针
	* @param Out     : 待输出串指针
	* @param datalen : 待加密串的长度，同时Out的缓冲区大小应大于或者等于datalen
	* @param Key     : 密钥(可为8位,16位,24位)支持3密钥
	* @param keylen  : 密钥长度，多出24位部分将被自动裁减
	* @return true--成功；false--失败；
	*/
	static bool RunDES(bool bType, bool bMode, int PaddingMode, const unsigned char* IV, const unsigned char* In,
		unsigned char* Out, unsigned datalen, const unsigned char* Key, unsigned keylen);

private:
	/*static int hexCharToInt(char c);*/
	enum {
   
		ENCRYPT = 0,    // 加密  
		DECRYPT,          // 解密  
	};

	enum {
   
		ECB = 0,      // ECB模式  
		CBC             // CBC模式  
	};
	  
	enum {
   
		PAD_ISO_1 = 0,  // ISO_1填充：数据长度不足8比特的倍数，以0x00补足，如果为8比特的倍数，补8个0x00  
	};
}; 
#endif

DES.cpp

#include "DES.h"
#include "memory.h"
#include <iostream>
#include<fstream>
using namespace std;

/* initial permutation IP */
const char IP_Table[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
};

/* final permutation IP^-1 */
const char IPR_Table[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
};

/* expansion operation matrix */
const char E_Table[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
};

/* 32-bit permutation function P used on the output of the S-boxes */
const char P_Table[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
};

/* permuted choice table (key) */
const char PC1_Table[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
};

/* permuted choice key (table) */
const char PC2_Table[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
};

/* number left rotations of pc1 */
const char LOOP_Table[