des.cpp

des加密算法 des加密算法 des加密算法 解密

#ifndef _DES_H_
#define _DES_H_

#include <iostream>
using namespace std;

#define BIT	 unsigned char
#define BYTE unsigned char

class Des
{
private:	
	BIT	subKey[16][48];				// 16圈子密钥
	
	static BYTE IpTable[64];		// 置换IP表
	static BYTE IprTable[64];		// 逆置换IP-1表
	static BYTE Etable[48];			// E 位选择表(拓展置换）
	static BYTE Ptable[32];			// P换位表
	static BYTE Pc1Table[56];		// pc1选位表
	static BYTE Pc2Table[48];		// pc2选位表
	static BYTE LoopTable[16];		// 左移位数表
	static BYTE Sbox[8][4][16];		// S盒
	
public:
	Des();
	
	void Cipher(BYTE out[16], const BYTE in[8]);							// 加密64位输入
	void InvCipher(BYTE out[8], const BYTE in[8]);                          // 解密64位输入
	
	void SetKey(const BYTE key[8]);											// 设置密钥
	static void Ffunc(BIT in[32], const BIT ki[48]);						// f函数
	static void Sfunc(BIT out[32], const BIT in[48]);						// s盒代替
	static void RotateL(BIT *in, int len, int loop);						// 循环左移
	static void Xor(BIT *ina, const BIT *inb, int len);						// 异或
	static void ByteToBit(BIT *out, const BYTE *in, int bits);			    // 明文的字节组转换成位组
    static void ByteToBit_KEY(BIT *out, const BYTE *in, int bits);			// 密钥的字节组转换成位组
	static void ByteToBit_S(BIT *out, const BYTE *in, int bits);	        //S函数的字节组转换成位组
	static void BitToByte(BYTE *out, const BIT *in, int bits);				// 位组转换成字节组
	static void Transform(BIT *out, BIT *in, const BYTE *table, int len);	// 变换（凡涉及表格转换的均使用此函数） 
	
private:
	Des(const Des& des);
	Des operator=(const Des& des);
};

#endif

Des::Des()
{
}

// 置换IP表
BYTE 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
BYTE 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
BYTE 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
BYTE 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
BYTE 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
BYTE 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
BYTE Des::LoopTable[16] = {
	1,  1,  2,  2,  2,  2,  2,  2,
		1,  2,  2,  2,  2,  2,  2,  1
};

// S盒
BYTE 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16轮子密钥
void Des::SetKey(const BYTE key[16])
{
	static BIT	k[64], 
		*kl=&k[0], 
		*kr=&k[28];
	
	ByteToBit_KEY(k, key, 64);						//将输入的16字节转换为64位（在本程序中用一个字节长度储存一个位）
	
	Transform(k, k, Pc1Table, 56);					//置换选择P1，此时k数组中有56位
	
	for(int i=0; i<16; i++)
	{
		RotateL(kl, 28, LoopTable[i]);				//前28位进行循环左移
		
		RotateL(kr, 28, LoopTable[i]);				//后28位进行循环左移
		
		Transform(subKey[i], k, Pc2Table, 48);		//置换选择P2，此时k数组有48位
	}
}

// f函数
void Des::Ffunc(BIT in[32], const BIT ki[48])		//明文为in数组，子密钥位ki数组
{
	static BIT mr[48];
	
	Transform(mr, in, Etable, 48);					// 扩展置换，结果在mr数组中
	
	Xor(mr, ki, 48);								// mr与子密钥异或，结果在mr数组中
	
	Sfunc(in, mr);									// S盒替换
	
	Transform(in, in, Ptable, 32);					// P盒替换
}

// s盒代替
void Des::Sfunc(BIT out[32], const BIT in[48])
{
	for(BYTE i=0, j, k; i<8; i++, in+=6, out+=4)				//每次输入数组in移六位，输出数组out移四位，总共8轮 
	{ 
		j = (in[0] << 1) + in[5];								// 第一位和第六位相加 
		k = (in[1] << 3) + (in[2] << 2) + (in[3] << 1) + in[4]; //中间四位相加 
		ByteToBit_S(out, &Sbox[i][j][k], 4);					//根据i j k得到Sbox数组的元素，并将其转换为四位的bit存到out数组中 
	}
}

// 循环左移
void Des::RotateL(BIT *in, int len, int loop)
{
	static BIT tmp[256];
	memcpy(tmp, in, sizeof(BIT) * loop);
	memcpy(in, in+loop, sizeof(BIT) * (len-loop));
	memcpy(in+len-loop, tmp, sizeof(BIT) * loop);
}

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

// 密钥的字节组转换成位组
void Des::ByteToBit_KEY(BIT *out, const BYTE *in, int bits)
{
	BYTE key_in[16];
	int i;
	for(i=0; i<bits/4;i++)
	{
		switch(in[i])                     //取key_in数组元素的右四位
		{
		case '0':key_in[i]=0x00;break;
		case '1':key_in[i]=0x10;break;
		case '2':key_in[i]=0x20;break;
		case '3':key_in[i]=0x30;break;
		case '4':key_in[i]=0x40;break;
		case '5':key_in[i]=0x50;break;
		case '6':key_in[i]=0x60;break;
		case '7':key_in[i]=0x70;break;
		case '8':key_in[i]=0x80;break;
		case '9':key_in[i]=0x90;break;
		case 'A':key_in[i]=0xA0;break;
		case 'B':key_in[i]=0xB0;break;
		case 'C':key_in[i]=0xC0;break;
		case 'D':key_in[i]=0xD0;break;
		case 'E':key_in[i]=0xE0;break;
		case 'F':key_in[i]=0xF0;break;
									
		}
	}
	for(i=0; i<bits; i++)
	{
		out[i] = (key_in[i/4] << (i%4)) & 0x80;
		out[i]>>=7;
	}
}

//S函数的字节组转换成位组
void Des::ByteToBit_S(BIT *out, const BYTE *in, int bits)
{
	int i;
	BYTE tmp=*in;
	tmp<<=4;
	for(i=0; i<bits; i++)
	{
		out[i] = (tmp << (i%4)) & 0x80;
		out[i]>>=7;
	}
}

// 明文的字节组转换成位组
void Des::ByteToBit(BIT *out, const BYTE *in, int bits)
{
	int i;
	for(i=0; i<bits; i++)
	{
		out[i] = (in[i/8] << (i%8)) & 0x80;
		out[i]>>=7;
	}
}

// 位组转换成字节组
void Des::BitToByte(BYTE *out, const BIT *in, int bits)
{
	BYTE tmp[256];
	memset(out, 0, (bits+7) / 8);
	memset(tmp,0,bits);
    
	for(int i=0; i<bits; i++)
	{
		tmp[i]=in[i]<<(7-i%8);
		out[i/8] |=tmp[i];
	}
}

// 变换			
void Des::Transform(BIT *out, BIT *in, const BYTE *table, int len)
{
	static BIT tmp[256];
	
	for(int i=0; i<len; i++)
	{
		tmp[i] = in[table[i]-1];
	}
	
	memcpy(out, tmp, sizeof(BIT) * len); 
}

// 加密64位输入
void Des::Cipher(BYTE out[8], const BYTE in[8])
{
	static BIT	m[64],
		tmp[32],
		*li = &m[0], 
		*ri=&m[32];
	
	ByteToBit(m, in, 64);
	
	Transform(m, m, IpTable, 64);
	
	for(int i=0; i<16; i++)
	{
		memcpy(tmp, ri, 32);
		
		Ffunc(ri, subKey[i]);
		
		Xor(ri, li, 32);
		
		memcpy(li, tmp, 32);
	}
	
    memcpy(tmp, ri, 32);
    memcpy(ri,li,32);
    memcpy(li, tmp, 32);
	
	Transform(m, m, IprTable, 64);
	
	BitToByte(out, m, 64);
}

// 解密64位输入
void Des::InvCipher(BYTE out[8], const BYTE in[8])
{
	static BIT	m[64],
		tmp[32],
		*li = &m[0], 
		*ri=&m[32];
	
	ByteToBit(m, in, 64);
	
	
	
	Transform(m, m, IpTable, 64);
	
	
	
	for(int i=15; i>=0; i--)
	{
		memcpy(tmp, ri, 32);
		
		Ffunc(ri,subKey[i]);
		
		Xor(ri, li, 32);
		
		memcpy(li, tmp, 32);
	}
	
	memcpy(tmp, ri, 32);
    memcpy(ri,li,32);
    memcpy(li, tmp, 32);
	
	Transform(m, m, IprTable, 64);

	BitToByte(out, m, 64);
}

#include <iostream>
using namespace std;

int  main()
{
	BYTE key[20],	
		str[20],out[20];
	int i;

	cout<<"Input Key:"<<endl;
					
	cin>>key;									//输入密钥

	cout<<"Input PlainText:"<<endl;
	
	cin>>str;									//输入明文
	
	   Des des;
	   
	   des.SetKey(key);                         //计算十六轮子密钥
	    
       des.Cipher(out, str);					//加密明文

	   cout<<"CipherText:"<<endl;
	   
	   for(i = 0;i < 8;i++)						//输出密文
		   printf("%02X",out[i]);
	   printf("\n");
	   
	   
	   cout<<"Decryption:"<<endl;                //解密后的结果
	   
       des.InvCipher(str, out);
	   
       cout<<str<<endl;
	   
       return 0;
}