des.cpp

des加密算法 des加密算法 des加密算法 解密

#include <iostream>
using namespace std;
#define zero 0;
class Des
{
private:	

	bool	subKey[16][48];				// 16圈子密钥
	static char Etable[48];			// E 位选择表
	static char Ptable[32];			// P换位表
	static char IpTable[64];		// 置换IP表
	static char IprTable[64];		// 逆置换IP-1表
	static char Pc1Table[56];		// pc1选位表
	static char Pc2Table[48];		// pc2选位表
	static char LoopTable[16];		// 左移位数表
	static char Sbox[8][4][16];		// S盒

public:
	Des()
	{
	}
    void Cipher(char out[8], const char in[8]);		// 加密64位输入
	void InvCipher(char out[8], const char in[8]);  // 解密64位输入
	void SetKey(const char key[8]);											// 设置密钥
	static void Ffunc(bool in[32], const bool ki[48]);							// f函数
	static void Sfunc(bool out[32], const bool in[48]);						// s盒代替
	static void RotateL(bool *in, int len, int loop);						// 循环左移
	static void Xor(bool *ina, const bool *inb, int len);						// 异或
	static void charTobool(bool *out, const char *in, int bools);				// 字节转换成二进制位
	static void boolTochar(char *out, const bool *in, int bools);				// 二进制位转换成字节
	static void Transform(bool *out, bool *in, const char *table, int len);	 // 变换

  
};





// 置换IP表
 char Des::IpTable[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
};

// 逆置换IP-1表
char Des::IprTable[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
};

// E 位选择表
char Des::Etable[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
};

// P换位表
char Des::Ptable[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
};

// pc1选位表
char Des::Pc1Table[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
};

// pc2选位表
char Des::Pc2Table[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
};

// 左移位数表
char Des::LoopTable[16] = {
	 1,  1,  2,  2,  2,  2,  2,  2,
	 1,  2,  2,  2,  2,  2,  2,  1
};

// S盒
char Des::Sbox[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
};

// 生成子密钥
void Des::SetKey(const char key[8])   
{
	static bool	k[64], 
				*kl=&k[0], 
				*kr=&k[28];

	charTobool(k, key, 64);     //将字节数组转换成二进制位

	Transform(k, k, Pc1Table, 56);  //从密钥源的64位选出56位

	for(int i=0; i<16; i++)     //16轮的迭代
	{
		RotateL(kl, 28, LoopTable[i]); //在迭代过程中要将56分成28位的两部分

		RotateL(kr, 28, LoopTable[i]);   //左右两部分都要进行循环左移，移动的次数和迭代的次数相关

		Transform(subKey[i], k, Pc2Table, 48);   //16轮迭代结束后56位密钥按表Pc2Table置换出48位
	}
}

// f函数
void Des::Ffunc(bool in[32], const bool ki[48])
{
	static bool mr[48];

	Transform(mr, in, Etable, 48);			// 将32位扩展扩展置换成48位等下和子密钥进行异或运算

	Xor(mr, ki, 48);						// 和子密钥进行异或运算

	Sfunc(in, mr);							// S盒替换，48位输入变成32位输出

	Transform(in, in, Ptable, 32);			// P盒替换，将S盒替换得到了32位重新按表Ptable排位置
}

// s盒代替，48位输入变成32位输出
void Des::Sfunc(bool out[32], const bool in[48])
{
	for(char i=0, j, k; i<8; i++, in+=6, out+=4) //第一位了第六位的值作为行，中间四位的值作为值
	{
		j = (in[0] << 1) + in[5];
		k = (in[1] << 3) + (in[2] << 2) + (in[3] << 1) + in[4];
		charTobool(out, &Sbox[i][j][k], 4);
	}
}

// 循环左移，迭代次数不同，移位次数也相应的不同
void Des::RotateL(bool *in, int len, int loop)   
{
	static bool tmp[256];
	memcpy(tmp, in, sizeof(bool) * loop);
	memcpy(in, in+loop, sizeof(bool) * (len-loop));
	memcpy(in+len-loop, tmp, sizeof(bool) * loop);
}

// 异或运算
void Des::Xor(bool *ina, const bool *inb, int len)
{
	for(int i=0; i<len; i++)
	{
		ina[i] ^= inb[i];
	}
}

// 字节转换成二进制位
void Des::charTobool(bool *out, const char *in, int bools)
{
	for(int i=0; i<bools; i++)
	{
		out[i] = (in[i/8] >> (i%8)) & 1;
	}
}

// 二进制位转换成字节
void Des::boolTochar(char *out, const bool *in, int bools)
{
	memset(out, 0, (bools+7) / 8);  //全部置0
    
	for(int i=0; i<bools; i++)  
	{
		out[i/8] |= in[i] << (i%8);
	}
}

// 对照表，把输入映射成输出，改变他们的位置		
void Des::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, sizeof(bool) * len);
}   

// 加密64位输入
void Des::Cipher(char out[8], const char in[8])
{
	static bool	m[64],
				tmp[32],
				*li = &m[0], 
				*ri=&m[32];

	charTobool(m, in, 64);    //先将8进制位转换成62位的二进制

	Transform(m, m, IpTable, 64);  //根据表IpTable进行初始置换

	for(int i=0; i<16; i++)      //16轮的迭代
	{
		memcpy(tmp, ri, 32);     //右边32位等下讲直接赋给下一轮的左边32位

		Ffunc(ri, subKey[i]);  //左边32位先和子密钥做一次运算

		Xor(ri, li, 32);      //右边和子密钥做完运算后的结果和左边再进行一次异或运算

		
		memcpy(li, tmp, 32);   //从数组tmp复制32位到li指针所指的数组
	}

	Transform(m, m, IprTable, 64); //根据表IprTable进行逆初始置换

	boolTochar(out, m, 64);       //再将二进制转换成8进制
}

// 解密64位输入
void Des::InvCipher(char out[8], const char in[8])  //
{
	static bool	m[64],
				tmp[32],
				*li = &m[0], 
				*ri=&m[32];

	charTobool(m, in, 64);

	Transform(m, m, IpTable, 64);  //解密时和加密时逆向的，先初始逆置换

	for(int i=15; i>=0; i--)   //所使用的子密钥的顺序和加密时的相反的
	{
		memcpy(tmp, li, 32);   

		Ffunc(li,subKey[i]);     //变成是左边的32位先进行运算

		Xor(li, ri, 32);

		memcpy(ri, tmp, 32);
	}

	Transform(m, m, IprTable, 64);   //初始置换

	boolTochar(out, m, 64);    //将二进制变成相应的8进制
}




int  main()
{     	 
	   Des des;
       char key[8],str[8];	
		   				
	   cout<<"Input Key: "<<endl;  

       cin>>key;  //输入密钥

       cout<<"Input PlainText: "<<endl;

       cin>>str;  //输入明文
       
	   des.SetKey(key);  //生成密钥

       des.Cipher(str, str);  //加密

       cout<<"CipherText: "<<endl<<str<<endl;

       cout<<"Decryption: "<<endl;

       des.InvCipher(str, str);  //解密

       cout<<str<<endl;

   
	   return 0;
}