工厂方法模式——C++实现

问题描述：

目前常用的加密算法有DES（Data Encryption Standard）和IDEA（International Data Encryption Algorithm）国际数据加密算法等，请用工厂方法实现加密算法系统。

C++代码：

#include <iostream>
#include <fstream>
#include <bitset>
#include <string>
using namespace std;
//define the type of data
typedef unsigned char byte;
typedef unsigned short word16;//16bit
typedef unsigned long word32;//32bit
//抽象产品类——PW类
class PW{
public:
    void show(){}
};
//具体产品类——IDEA类：
class IDEA:public PW
{
public:
	void setKey(byte in[]);
	void setPlainText(byte in[]);
	word16 invMul(word16 x);
	word16 mul(word16 x, word16 y);
	void encryption(word16 in[], word16 out[], word16 *Ek);
	void enc();
	void show();
private:
	void getEncRoundKey(word16 *encRoundKey);
	void getDecRoundKey(word16 *EK, word16 DK[]);
	byte key[16];
	word16 cipherText[4];
	word16 plainText[4];
	word16 deCipherText[4];
	word16 encRoundKey[52];
	word16 decRoundKey[52];
	void checkRoundKey();
};
void IDEA::setPlainText(byte in[]){
	//8个byte类型数据变成4个word16的数据
	int i;
	for (i=0; i<8; i+=2){
		plainText[i/2] = (in[i]<<8)+in[i+1];
	}
}
void IDEA::setKey(byte in[]){
	int i;
	for(i=0; i<16; i++){
		key[i] = in[i];
	}
	getEncRoundKey(encRoundKey);
	getDecRoundKey(encRoundKey, decRoundKey);
}
void IDEA::getEncRoundKey(word16 *encRoundKey){
	int i,j;
	for(i=0,j=0; j<8; j++){
		encRoundKey[j] = (key[i]<<8) + key[i+1];
		i+=2;
	}
	for(i=0; j<52; j++){
		i++;
		encRoundKey[i+7] = encRoundKey[i&7] << 9 | encRoundKey[(i+1) & 7] >> 7;
		encRoundKey += (i & 8);
		i &= 7;
	}
}
void IDEA::getDecRoundKey(word16 *EK, word16 DK[]){
	int i;
	word16 temp[52];
	word16 t1,t2,t3;
	word16 *p = temp + 52;
	t1 = invMul(*EK ++);
	t2 = - *EK ++;
	t3 = - *EK ++;
	*--p = invMul(*EK ++);
	*--p = t3;
	*--p = t2;
	*--p = t1;
	for(i=0; i<7; i++){
		t1 = *EK++;
		*--p = *EK++;
		*--p = t1;
		t1 = invMul(*EK++);
		t2 = - *EK ++;
		t3 = - *EK ++;
		*--p = invMul(*EK++);
		*--p = t2;
		*--p = t3;
		*--p = t1;
	}
	t1 = *EK++;
	*--p = *EK++;
	*--p = t1;
	t1 = invMul(*EK++);
	t2 = - *EK ++;
	t3 = - *EK ++;
	*--p = invMul(*EK++);
	*--p = t3;
	*--p = t2;
	*--p = t1;
	for(i=0,p=temp; i<52; i++){
		*EK++ = *p;
		*p++ = 0;
	}
}
word16 IDEA::invMul(word16 x){
	word16 t0,t1;
	word16 q,y;
	if(x<=1){
		return x;//0和1的逆是本身
	}
	t1 = word16(0x10001L/x);
	y = word16(0x10001L%x);
	if(y == 1){
		return (1-t1) & 0xFFFF;
	}
	t0 = 1;
	do{
		q = x/y;
		x = x%y;
		t0 += q*t1;
		if(x == 1){
			return t0;
		}
		q = y/x;
		y = y%x;
		t1 += q*t0;
	}while(y!=1);
	return (1-t1) & 0xFFFF;
}
void IDEA::encryption(word16 in[], word16 out[], word16 * EK){
	word16 x1,x2,x3,x4,t1,t2;
	x1 = in[0];
	x2 = in[1];
	x3 = in[2];
	x4 = in[3];
	int r = 8;
	do{
		x1 = mul(x1, *EK++);
		x2 += *EK++;
		x3 += *EK++;
		x4 = mul(x4, *EK++);
		t2 = x1 ^ x3;
		t1 = x2 ^ x4;
		t2 = mul(t2, *EK++);
		t1 = t1 + t2;
		t1 = mul(t1, *EK++);
		t2 = t1 + t2;
		x1 ^= t1;
		x4 ^= t2;
		t2 ^= x2;
		x2 = x3 ^ t1;
		x3 = t2;
	}while(--r);
	x1 = mul(x1, *EK++);
	*out++ = x1;
	*out++ = x3 + *EK++;
	*out++ = x2 + *EK++;
	x4 = mul(x4, *EK++);
	*out = x4;
}
word16 IDEA::mul(word16 x, word16 y){
	word32 p;
	p = (word32)x * y;
	if(p){
		y = p & 0xFFFF;
		x = p >> 16;
		return (y-x) + (y<x);
	}else if (x){
		return 1-y;
	}else{
		return 1-x;
	}
}
void IDEA::enc(){
	encryption(plainText, cipherText, encRoundKey);
	encryption(cipherText, deCipherText, decRoundKey);
}
void IDEA::show(){
	cout<<"输入文本:"<<endl;
	int i;
	for(i=0; i<16; i++){
		cout<<hex<<int(key[i])<<" ";
	}
	cout<<endl;
	cout<<"初始文本:"<<endl;
	for(i=0; i<4; i++){
		cout<<hex<<plainText[i]<<" ";
	}
	cout<<endl;
	cout<<"密文:"<<endl;
	for(i=0; i<4; i++){
		cout<<hex<<cipherText[i]<<" ";
	}
	cout<<endl;
	cout<<"解密文本:"<<endl;
	for(i=0; i<4; i++){
		cout<<hex<<deCipherText[i]<<" ";
	}
	cout<<endl;
}

/****************************DES算法********************************/

bitset<64> key;                // 64位密钥
bitset<48> subKey[16];         // 存放16轮子密钥

// 初始置换表
int IP[] = {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};

// 结尾置换表
int IP_1[] = {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};

/*------------------下面是生成密钥所用表-----------------*/

// 密钥置换表，将64位密钥变成56位
int PC_1[] = {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};

// 压缩置换，将56位密钥压缩成48位子密钥
int PC_2[] = {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};

// 每轮左移的位数
int shiftBits[] = {1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1};

/*------------------下面是密码函数 f 所用表-----------------*/

// 扩展置换表，将 32位 扩展至 48位
int E[] = {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};

// S盒，每个S盒是4x16的置换表，6位 -> 4位
int S_BOX[8][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}
	},
	{
		{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}
	},
	{
		{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}
	},
	{
		{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}
	},
	{
		{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}
	},
	{
		{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}
	},
	{
		{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}
	},
	{
		{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置换，32位 -> 32位
int P[] = {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 };

/**********************************************************************/
/*                                                                    */
/*                            下面是DES算法实现                         */
/*                                                                    */
/**********************************************************************/

/**
 *  密码函数f，接收32位数据和48位子密钥，产生一个32位的输出
 */
bitset<32> f(bitset<32> R, bitset<48> k)
{
	bitset<48> expandR;
	// 第一步：扩展置换，32 -> 48
	for(int i=0; i<48; ++i)
		expandR[47-i] = R[32-E[i]];
	// 第二步：异或
	expandR = expandR ^ k;
	// 第三步：查找S_BOX置换表
	bitset<32> output;
	int x = 0;
	for(int i=0; i<48; i=i+6)
	{
		int row = expandR[47-i]*2 + expandR[47-i-5];
		int col = expandR[47-i-1]*8 + expandR[47-i-2]*4 + expandR[47-i-3]*2 + expandR[47-i-4];
		int num = S_BOX[i/6][row][col];
		bitset<4> binary(num);
		output[31-x] = binary[3];
		output[31-x-1] = binary[2];
		output[31-x-2] = binary[1];
		output[31-x-3] = binary[0];
		x += 4;
	}
	// 第四步：P-置换，32 -> 32
	bitset<32> tmp = output;
	for(int i=0; i<32; ++i)
		output[31-i] = tmp[32-P[i]];
	return output;
}

/**
 *  对56位密钥的前后部分进行左移
 */
bitset<28> leftShift(bitset<28> k, int shift)
{
	bitset<28> tmp = k;
	for(int i=27; i>=0; --i)
	{
		if(i-shift<0)
			k[i] = tmp[i-shift+28];
		else
			k[i] = tmp[i-shift];
	}
	return k;
}

/**
 *  生成16个48位的子密钥
 */
void generateKeys()
{
	bitset<56> realKey;
	bitset<28> left;
	bitset<28> right;
	bitset<48> compressKey;
	// 去掉奇偶标记位，将64位密钥变成56位
	for (int i=0; i<56; ++i)
		realKey[55-i] = key[64 - PC_1[i]];
	// 生成子密钥，保存在 subKeys[16] 中
	for(int round=0; round<16; ++round)
	{
		// 前28位与后28位
		for(int i=28; i<56; ++i)
			left[i-28] = realKey[i];
		for(int i=0; i<28; ++i)
			right[i] = realKey[i];
		// 左移
		left = leftShift(left, shiftBits[round]);
		right = leftShift(right, shiftBits[round]);
		// 压缩置换，由56位得到48位子密钥
		for(int i=28; i<56; ++i)
			realKey[i] = left[i-28];
		for(int i=0; i<28; ++i)
			realKey[i] = right[i];
		for(int i=0; i<48; ++i)
			compressKey[47-i] = realKey[56 - PC_2[i]];
		subKey[round] = compressKey;
	}
}

/**
 *  工具函数：将char字符数组转为二进制
 */
bitset<64> charToBitset(const char s[8])
{
	bitset<64> bits;
	for(int i=0; i<8; ++i)
		for(int j=0; j<8; ++j)
			bits[i*8+j] = ((s[i]>>j) & 1);
	return bits;
}

/**
 *  DES加密
 */
bitset<64> encrypt(bitset<64>& plain)
{
	bitset<64> cipher;
	bitset<64> currentBits;
	bitset<32> left;
	bitset<32> right;
	bitset<32> newLeft;
	// 第一步：初始置换IP
	for(int i=0; i<64; ++i)
		currentBits[63-i] = plain[64-IP[i]];
	// 第二步：获取 Li 和 Ri
	for(int i=32; i<64; ++i)
		left[i-32] = currentBits[i];
	for(int i=0; i<32; ++i)
		right[i] = currentBits[i];
	// 第三步：共16轮迭代
	for(int round=0; round<16; ++round)
	{
		newLeft = right;
		right = left ^ f(right,subKey[round]);
		left = newLeft;
	}
	// 第四步：合并L16和R16，注意合并为 R16L16
	for(int i=0; i<32; ++i)
		cipher[i] = left[i];
	for(int i=32; i<64; ++i)
		cipher[i] = right[i-32];
	// 第五步：结尾置换IP-1
	currentBits = cipher;
	for(int i=0; i<64; ++i)
		cipher[63-i] = currentBits[64-IP_1[i]];
	// 返回密文
	return cipher;
}

/**
 *  DES解密
 */
bitset<64> decrypt(bitset<64>& cipher)
{
	bitset<64> plain;
	bitset<64> currentBits;
	bitset<32> left;
	bitset<32> right;
	bitset<32> newLeft;
	// 第一步：初始置换IP
	for(int i=0; i<64; ++i)
		currentBits[63-i] = cipher[64-IP[i]];
	// 第二步：获取 Li 和 Ri
	for(int i=32; i<64; ++i)
		left[i-32] = currentBits[i];
	for(int i=0; i<32; ++i)
		right[i] = currentBits[i];
	// 第三步：共16轮迭代（子密钥逆序应用）
	for(int round=0; round<16; ++round)
	{
		newLeft = right;
		right = left ^ f(right,subKey[15-round]);
		left = newLeft;
	}
	// 第四步：合并L16和R16，注意合并为 R16L16
	for(int i=0; i<32; ++i)
		plain[i] = left[i];
	for(int i=32; i<64; ++i)
		plain[i] = right[i-32];
	// 第五步：结尾置换IP-1
	currentBits = plain;
	for(int i=0; i<64; ++i)
		plain[63-i] = currentBits[64-IP_1[i]];
	// 返回明文
	return plain;
}
//具体产品类——DES类：
class DES:public PW{
public:
    DES(){
        cout<<"DES加密算法："<<endl;
        show();
    }
    void show(){
		string s = "张紫诺";
		string k = "12345678";
		bitset<64> temp;
		fstream file1;
		bitset<64> plain = charToBitset(s.c_str());
		key = charToBitset(k.c_str());
		// 生成16个子密钥
		generateKeys();
		// 密文写入 a.txt
		bitset<64> cipher = encrypt(plain);
		file1.open(".//a.txt", ios::binary | ios::out);
		file1.write((char*)&cipher,sizeof(cipher));
		file1.close();
		// 读文件 a.txt
		file1.open(".//a.txt", ios::binary | ios::in);
		file1.read((char*)&temp, sizeof(temp));
		cout<<"密文： "<<(char*)&temp<<endl;
		file1.close();
		// 解密，并写入文件 b.txt
		bitset<64> temp_plain = decrypt(cipher);
		cout<<"解密： "<<(char*)&temp_plain<<endl;
    }
};
//抽象工厂类——PWFactory类
class PWFactory{
public:
    virtual PW producePW()=0;
};
//具体工厂类——DESFactory类
class DESFactory:public PWFactory{
public:
    virtual PW producePW(){
		DES des;
		return des;
	}
};
//具体工厂类——IDEAFactory类
class IDEAFactory:public PWFactory{
public:
    virtual PW producePW(){
		IDEA idea;
		byte key[16] = {0x10, 0x1A, 0x0C, 0x0B, 0x01, 0x11, 0x09, 0x07, 0x32, 0xA1, 
		0xB3, 0x06, 0x23, 0x12, 0xD3, 0xF1};
		idea.setKey(key);
		byte plainText[8] = {0xA7, 0x95, 0x87, 0x23, 0x1F, 0x2C, 0x6D, 0x73};
		idea.setPlainText(plainText);
		cout<<"IDEA算法："<<endl;
		idea.enc();
		idea.show();
		return idea;
	}
};

int main()
{
	PW pw;
	PWFactory *f;
	int i;
	cout<<"请选择：1.DES算法  2.IDEA算法"<<endl;
	cin>>i;
	if(i==1){
		f=new DESFactory();
		pw=f->producePW();
	}else if(i==2){
		f=new IDEAFactory();
		pw=f->producePW();
	}else{
		cout<<"输入无效！"<<endl;
	}
	return 0;
}

运行结果：

DES；

IDEA：