DES加密算法C++实现

DES的C++实现,需要两个文件,一个table.h,一个DES.h
该算法优点:纯位运算实现,速度快,嵌套内部类,实现完全封装,使用简单,只需要传入字节数组即可实现加密解密.
缺点:位运算需要一个一个复杂设计,对于代码理解几乎不可能,定义过多结构体,导致代码过长.
接下来贴源码

DES.h

#pragma once
#include "table.h"
#include 
/*
*构造方法:传入秘钥(即c字符串),并,将c字符串转化为内部类(DESKey),内部类处理c字符串,转化为能处理的数据结构
*bdata-n,秘钥长度是固定的.
*
*使用方法: 外部调用public函数decode(char*)或者decode(bdata*),鉴于这是一个工具类,我们不需要添加bdata结构对象.
*返回一个bdata-n数组指针.外部调用encode(bdata*)
*
*/
class DES {
public:
	typedef struct BDATA64
	{
		//8*8=64
		char bit[8];
	}bdata64;
private:
	typedef struct BDATA56
	{
		char bit[7];
	}bdata56;
	typedef struct BDATA32
	{
		char bit[4];
	}bdata32;
	typedef struct BDATA48
	{
		char bit[6];
	}bdata48;
	typedef struct BDATA28
	{
		char bit[4];//28位的bit我们只能用32位的代替,多余的四位用不上.
	}bdata28;


	class DESKey {
	private:
		//计算十六轮,每一轮要用的秘钥c0,d0转化为exkey.
		int distributeKey(bdata28* c0, bdata28* d0, int times)
		{
			char table[] = { 0,1,3 };
			//赋值三个char,以及四个位
			for (int i = 0; i < 3; i++)
			{
				c0->bit[i] = realkey.bit[i];
				d0->bit[3 - i] = realkey.bit[6 - i];
			}
			char temp = realkey.bit[3];
			c0->bit[3] = temp & 0xf0;
			d0->bit[0] = temp & 0x0f;

			int step = keytable3[times];
			char buf = c0->bit[0];
			char buf2 = d0->bit[0];
			for (int i = 0; i < 3; i++)
			{
				//theshift是要补入的一位或两位
				char theshift = c0->bit[i + 1];
				theshift = theshift >> (8 - step);
				theshift = theshift & table[step];
				c0->bit[i] = c0->bit[i] << step;
				c0->bit[i] = c0->bit[i] & (~table[step]);//需要移入的位先置位0
				c0->bit[i] = c0->bit[i] | theshift;
				//d0
				theshift = d0->bit[i + 1];
				theshift = theshift >> (8 - step);
				theshift = theshift & table[step];
				d0->bit[i] = d0->bit[i] << step;
				d0->bit[i] = d0->bit[i] & (~table[step]);//置位0
				d0->bit[i] = d0->bit[i] | theshift;

			}
			buf = buf >> (4 - step);
			buf = buf & (table[step] << 4);
			c0->bit[3] = c0->bit[3] << step;
			c0->bit[3] = c0->bit[3] & (~(table[step] << 4));
			c0->bit[3] = c0->bit[3] | buf;

			buf2 = buf2 >> (4 - step);
			buf2 = buf2 & (table[step]);
			d0->bit[3] = d0->bit[3] << step;
			d0->bit[3] = d0->bit[3] & (~table[step]);
			d0->bit[3] = d0->bit[3] | buf2;
			d0->bit[0] = d0->bit[0] & 0x0f;//保持d0前四位为0的格式

			return 0;
		}
		int exKey(bdata28 c0, bdata28 d0, bdata48* exkey)
		{
			char buf;//buf用于暂存当前bit位所在的字节
			char table[] = { -128,64,32,16,8,4,2,1 };
			for (int i = 0; i < 48; i++)
			{
				int position = exkeytable[i] - 1;
				int row = position / 8;
				int offset = position % 8;
				if (row >= 3 && offset > 3)
				{
					buf = d0.bit[row - 3];
				}
				else
				{
					buf = c0.bit[row];
				}
				int answer = buf & table[offset];
				if (answer)
				{
					row = i / 8;
					offset = i % 8;
					exkey->bit[row] = exkey->bit[row] | table[offset];
				}
				else
				{
					row = i / 8;
					offset = i % 8;
					exkey->bit[row] = exkey->bit[row] & (~table[offset]);
				}
			}
			return 0;
		}
		int mergeKey(bdata28 c0, bdata28 d0)
		{
			for (int i = 0; i < 3; i++)
			{
				realkey.bit[i] = c0.bit[i];
			}
			for (int i = 4; i < 7; i++)
			{
				realkey.bit[i] = d0.bit[i - 3];
			}
			c0.bit[3] = c0.bit[3] & 0xf0;
			d0.bit[0] = d0.bit[0] & 0x0f;
			realkey.bit[3] = c0.bit[3] | d0.bit[0];
			return 0;
		}
		void keyOperate() {
			bdata28 c0, d0;
			for (int i = 0; i <= 15; i++) {
				distributeKey(&c0, &d0, i);
				exKey(c0, d0, &exkey[i]);
				mergeKey(c0, d0);
			}
		}
	public:
		void showExKey() {
			for (int i = 0; i < 16; i++) {
				printf("the %d th exkey ", i + 1);
				for (int j = 0; j < 6; j++) {

					printf("%d ", exkey[i].bit[j]);

				}
				printf("\n");
			}
		}
		void showRawKey() {
			for (int i = 0; i < 8; i++) {
				printf("%d ", rawkey.bit[i]);
			}
			printf("\n");
		}
		void showRealKey() {
			for (int i = 0; i < 7; i++) {
				printf("%d ", realkey.bit[i]);
			}
			printf("\n");
		}
		bdata56 realkey;
		bdata64 rawkey;
		bdata48 exkey[16];
		DESKey(char* cp)
		{

			int length = strlen(cp);

			length < 8 ? true : length = 8;

			for (int i = 0; i < length; i++) {
				rawkey.bit[i] = *cp;
				cp++;
			}

			for (int i = length; i < 8; i++) {
				rawkey.bit[i] = 0;
				cp++;
			}

			char table[] = { -128,64,32,16,8,4,2,1 };
			//rawkey to realkey
			for (int i = 0; i < 56; i++)
			{
				int position = keytable1[i] - 1;
				int row = position / 8;
				int offset = position % 8;
				//我们需要获得他所在的位
				int answer = rawkey.bit[row] & table[offset];
				//answer确定所选位是否使能
				if (answer)
				{
					row = i / 8;
					offset = i % 8;
					realkey.bit[row] = realkey.bit[row] | table[offset];
				}
				else
				{
					row = i / 8;
					offset = i % 8;
					realkey.bit[row] = realkey.bit[row] & (~table[offset]);
				}
			}
			keyOperate();
		};
	};



	void ipExchange(bdata64* m);
	void extendRdata(bdata32, bdata48*);
	void xorEdata(bdata48*, bdata48);
	void sBox(bdata48 edata, bdata32* result);
	void pExchange(bdata32*);
	void unipExchange(bdata64*);
public:
	DESKey key;
	//返回一个指针,这个指针是bdata类型指针,指向bdata数组的第一个元素.
	DES(char* cp) :key(cp) {};
	//n是bdata64数量
	static void showBdata64InB(bdata64* p, int n);
	static void showBdata64InC(bdata64* p, int n);

	bdata64* decode(char* p);
	bdata64* decode(bdata64* p, int n);
	bdata64* encode(char* p);
	bdata64* encode(bdata64* p, int n);

};


DES::bdata64* DES::encode(char* p) {
	int length = strlen(p);
	int num = ((length - 1) / 8) + 1;
	bdata64* mingwen = new bdata64[num];
	for (int i = 0; i < length; i++) {
		mingwen[i / 8].bit[i % 8] = *(p + i);
	}
	for (int i = length; i < num * 8; i++) {
		mingwen[i / 8].bit[i % 8] = 0;
	}
	return encode(mingwen, num);
}


DES::bdata64* DES::encode(DES::bdata64* pt, int n) {
	//我们不希望破坏原来的明文,所以new内存
	bdata64* m = new bdata64[n];//密文对象数组
	for (int k = 0; k < n; k++) {
		bdata64 mt = *(pt + k);//对这个temp对象进行修改.
		ipExchange(&mt);//mt被重映射
		bdata32 rdata, ldata;
		bdata32 SOUT;
		bdata48 edata;
		for (int i = 0; i <= 15; i++) {
			for (int j = 0; j < 4; j++) {
				ldata.bit[j] = mt.bit[j];
				rdata.bit[j] = mt.bit[j + 4];
			}
			extendRdata(rdata, &edata);
			xorEdata(&edata, key.exkey[i]);
			sBox(edata, &SOUT);
			pExchange(&SOUT);
			for (int j = 0; j < 4; j++) {
				mt.bit[j + 4] = SOUT.bit[j] ^ ldata.bit[j];
				mt.bit[j] = rdata.bit[j];
			}
		}
		//after the last loop , exchange left and right.
		bdata64 temp = mt;
		for (int j = 0; j < 4; j++)
		{
			mt.bit[j + 4] = temp.bit[j];
			mt.bit[j] = temp.bit[j + 4];
		}
		unipExchange(&mt);
		m[k] = mt;
	}
	return m;
}

DES::bdata64* DES::decode(char* p) {
	int length = strlen(p);
	int num = (length - 1 / 8) + 1;
	bdata64* miwen = new bdata64[num];
	for (int i = 0; i < length; i++) {
		miwen[i / 8].bit[i % 8] = *(p + i);
	}
	for (int i = length; i < num * 8; i++) {
		miwen[i / 8].bit[i % 8] = 0;
	}
	return decode(miwen, num);
}

DES::bdata64* DES::decode(bdata64* p, int n) {
	//我们不希望破坏原来的密文,所以new内存
	bdata64* m = new bdata64[n];//明文对象数组
	for (int k = 0; k < n; k++) {
		bdata64 mt = *(p + k);//对这个temp对象进行修改.
		ipExchange(&mt);//mt被重映射
		bdata32 rdata, ldata;
		bdata32 SOUT;
		bdata48 edata;
		for (int i = 0; i <= 15; i++) {
			for (int j = 0; j < 4; j++) {
				ldata.bit[j] = mt.bit[j];
				rdata.bit[j] = mt.bit[j + 4];
			}
			extendRdata(rdata, &edata);
			xorEdata(&edata, key.exkey[15 - i]);//这里是关键
			sBox(edata, &SOUT);
			pExchange(&SOUT);
			for (int j = 0; j < 4; j++) {
				mt.bit[j + 4] = SOUT.bit[j] ^ ldata.bit[j];
				mt.bit[j] = rdata.bit[j];
			}
		}
		//after the last loop , exchange left and right.
		bdata64 temp = mt;
		for (int j = 0; j < 4; j++)
		{
			mt.bit[j + 4] = temp.bit[j];
			mt.bit[j] = temp.bit[j + 4];
		}
		unipExchange(&mt);
		m[k] = mt;
	}
	return m;

}

void DES::ipExchange(bdata64* mp) {
	bdata64 oldmingwen = *mp;
	char table[] = { -128,64,32,16,8,4,2,1 };
	for (int i = 0; i < 64; i++)
	{
		int position = iptable[i] - 1;
		int row = position / 8;
		int offset = position % 8;
		int answer = oldmingwen.bit[row] & table[offset];
		if (answer)//该位置1
		{
			row = i / 8;
			offset = i % 8;
			mp->bit[row] = mp->bit[row] | table[offset];
		}
		else//该位置0
		{
			row = i / 8;
			offset = i % 8;
			mp->bit[row] = mp->bit[row] & (~table[offset]);
		}
	}
	return;
}
void DES::extendRdata(bdata32 rdata, bdata48* edata) {
	char table[] = { -128,64,32,16,8,4,2,1 };
	for (int i = 0; i < 48; i++)
	{
		int position = extendtable[i] - 1;
		int row = position / 8;
		int offset = position % 8;
		int answer = rdata.bit[row] & table[offset];
		if (answer)
		{
			row = i / 8;
			offset = i % 8;
			edata->bit[row] = edata->bit[row] | table[offset];
		}
		else
		{
			row = i / 8;
			offset = i % 8;
			edata->bit[row] = edata->bit[row] & (~table[offset]);
		}

	}
	return;
}
void DES::xorEdata(bdata48* edata, bdata48 exkey)
{
	for (int i = 0; i <= 6; i++)
	{
		edata->bit[i] = edata->bit[i] ^ exkey.bit[i];
	}
	return;
}
void DES::unipExchange(bdata64* mingwen) {
	bdata64 oldmingwen = *mingwen;
	char table[] = { -128,64,32,16,8,4,2,1 };
	for (int i = 0; i < 64; i++)
	{
		int position = iviptable[i] - 1;
		int row = position / 8;
		int offset = position % 8;
		int answer = oldmingwen.bit[row] & table[offset];
		if (answer)//该位置1
		{
			row = i / 8;
			offset = i % 8;
			mingwen->bit[row] = mingwen->bit[row] | table[offset];
		}
		else//该位置0
		{
			row = i / 8;
			offset = i % 8;
			mingwen->bit[row] = mingwen->bit[row] & (~table[offset]);
		}
	}
	return;
}
void DES::sBox(bdata48 edata, bdata32* result)
{
	char S[8] = { 0 };
	char table[] = { -128,64,32,16,8,4,2,1 };
	//取出第一和第六个bit位,
	char temp = edata.bit[0] & table[0];
	char temp2 = edata.bit[0] & table[5];
	temp = temp >> 6;
	temp = temp & table[6];//只保留有用位
	temp2 = temp2 >> 2;
	char temp3 = temp | temp2;
	temp = edata.bit[0] & 120;//其实只要最高位0即可,即取出中间四位
	temp = temp >> 3;
	S[0] = stable[0][temp3][temp];

	temp = edata.bit[0] & table[6];
	temp2 = edata.bit[1] & table[3];
	temp2 = temp2 >> 4;
	temp3 = temp | temp2;
	temp = edata.bit[0] & table[7];
	temp2 = edata.bit[1] & -32;
	temp2 = temp2 >> 5;
	temp2 = temp2 & 7;
	temp = temp << 3;
	temp = temp | temp2;
	S[1] = stable[1][temp3][temp];

	temp = edata.bit[1] & table[4];
	temp2 = edata.bit[2] & table[1];
	temp = temp >> 2;
	temp2 = temp2 >> 6;
	temp3 = temp | temp2;
	temp = edata.bit[1] & 7;
	temp = temp << 1;
	temp2 = edata.bit[2] & 128;
	temp2 = temp2 >> 7;
	temp2 = temp2 & table[7];//消除移位补位影响
	temp = temp | temp2;
	S[2] = stable[2][temp3][temp];

	temp = edata.bit[2] & table[2];
	temp2 = edata.bit[2] & table[7];
	temp = temp >> 4;
	temp3 = temp | temp2;
	temp = edata.bit[2] & 30;
	temp = temp >> 1;
	S[3] = stable[3][temp3][temp];

	//////////////////////////////////////////

	temp = edata.bit[3] & table[0];
	temp2 = edata.bit[3] & table[5];
	temp = temp >> 6;
	temp = temp & table[6];//消解移位头部副作用
	temp2 = temp2 >> 2;
	temp3 = temp | temp2;
	temp = edata.bit[3] & 120;//其实只要最高位0即可
	temp = temp >> 3;
	S[4] = stable[4][temp3][temp];

	temp = edata.bit[3] & table[6];
	temp2 = edata.bit[4] & table[3];
	temp2 = temp2 >> 4;
	temp3 = temp | temp2;
	temp = edata.bit[3] & table[7];
	temp2 = edata.bit[4] & -32;
	temp2 = temp2 >> 5;
	temp2 = temp2 & 7;
	temp = temp << 3;
	temp = temp | temp2;
	S[5] = stable[5][temp3][temp];

	temp = edata.bit[4] & table[4];
	temp2 = edata.bit[5] & table[1];
	temp = temp >> 2;
	temp2 = temp2 >> 6;
	temp3 = temp | temp2;
	temp = edata.bit[4] & 7;
	temp = temp << 1;
	temp2 = temp2 >> 7;
	temp2 = temp2 & table[7];
	temp = temp | temp2;
	S[6] = stable[6][temp3][temp];


	temp = edata.bit[5] & table[2];
	temp2 = edata.bit[5] & table[7];
	temp = temp >> 4;
	temp3 = temp | temp2;
	temp = edata.bit[5] & 30;
	temp = temp >> 1;
	S[7] = stable[7][temp3][temp];

	for (int i = 0; i <= 3; i++)
	{
		S[i * 2] = S[i * 2] << 4;
		result->bit[i] = S[i * 2] | S[i * 2 + 1];
	}

}

void DES::pExchange(bdata32 * SOUT)
{
	bdata32 backup = *SOUT;
	char table[] = { -128,64,32,16,8,4,2,1 };
	for (int i = 0; i < 32; i++)
	{
		int position = ptable[i] - 1;
		int row = position / 8;
		int offset = position % 8;
		int answer = backup.bit[row] & table[offset];
		if (answer)//该位置1
		{
			row = i / 8;
			offset = i % 8;
			SOUT->bit[row] = backup.bit[row] | table[offset];
		}
		else//该位置0
		{
			row = i / 8;
			offset = i % 8;
			SOUT->bit[row] = backup.bit[row] & (~table[offset]);
		}
	}
}


void DES::showBdata64InB(bdata64* p, int n) {

	char table[] = { -128,64,32,16,8,4,2,1 };
	for (int k = 0; k < n; k++) {
		bdata64 mingwen = *(p + k);
		printf("------\n");
		for (int i = 0; i < 64; i++)
		{
			char buf = mingwen.bit[i / 8] & table[i % 8];
			printf("%d ", (buf > 0) ? 1 : 0);
			if (i % 8 == 7)
				printf("\n");
		}
		printf("\n");
	}

	return;
}
void DES::showBdata64InC(bdata64* p, int n) {
	for (int k = 0; k < n; k++) {
		bdata64 mingwen = *(p + k);
		printf("------\n");
		for (int i = 0; i < 8; i++) {
			printf("%c ", mingwen.bit[i]);
		}
		printf("\n");
	}
}

table.h

#pragma once
//key初始置换表,我们省去了奇偶校验过程
int keytable1[] = { 57,49,41,33,25,17,9,//秘钥置换选择1
					1,58,50,42,34,26,18,//56
					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,
};

int iptable[] = {	58,50,42,34,26,18,10,2,//初始置换IP
					60,52,44,36,28,20,12,4,//64
					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,
};
int 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,
};
int keytable3[] = { 1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1 };
int extendtable[] = {	32,1,2,3,4,5,//密文选择扩展E  48
						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,
};
int exkeytable[] = { 14,17,11,24,1,5,//秘钥置换选择2
					3,28,15,6,21,10,//56
					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,
};
char stable[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,
};
int iviptable[] = {
	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,
};

使用示例与说明

#include "DES.h"
#include 
int main() {

	char a[9] = { '1','2','3','4','5','6','7','8','\0' };
	char text[10] = "hello DES";
	//明文八字节(除去0),所以密文也是正好一个bdata64
	//a作为秘钥
	DES myDes(a);//a作为秘钥传入构造函数,这里可以直接传一个char数组或者我定义的bdata64数据结构
	//加密text
	DES::bdata64* secret = myDes.encode(text);
	//打印加密后的二进制,可以用于查看
	DES::showBdata64InB(secret, 2);//show Bdata64 in binary
	//myDes.key.showExKey();这里还可以打印16个秘钥,但我这里注释了,如果想查看把注释取消就是
	DES::bdata64* mingwen = myDes.decode(secret, 2);//解密,需要注意后面的int代表几个bdata64,八个字节为一个bdata64,也就你明文长度除以8+1;
	DES::showBdata64InC(mingwen, 2);//打印明文
	delete secret;
	delete mingwen;
	getchar();
	return 0;
}