des.c

des数据加密算法原理与实现。

/********************************************************************/
/*DES加密程序			1998.3.11									*/
/*使用方法:															*/
/*		加密:		DES FILENAME	<CR>							*/
/*					TYPE PASSWORD FOR FILENAME  XXXXXXXX 8字节		*/
/*		解密:		DES FILENAME	<CR>							*/
/*					TYPE PASSWORD FOR FILENAME  XXXXXXXX 8字节		*/
/*在vc++1.5或tc2.0 DOS6.22下调试通过								*/
/********************************************************************/
/*置换算法:
	为完成char inblock[8]按换位表charip[64]变换到char outblock[8],先生
	成一个变换矩阵 char perm[i][j][k],i=16,j=16,k=8
	i:把输入的64bit分成四位一组,每次处理四位信息
	j:四位可表示0......15,共16个值
	k:对应j的每一个值,给出一个8字节的矩阵表示对应的位的值为1
	比如:
	char inblock{11111110b,
				 01011101b,
				 01011010b,
				 00010100b,
				 10101011b,
				 11111000b,
				 00000100b,
				 10000101b}
	则:
		char *perm[0][15]={00000001b,
						   00000001b,
						   00000000b,
						   00000000b,
						   00000001b,
						   00000001b,
						   00000000b,
						   00000000b}

		char *perm[1][14]={00000000b,
						   00000000b,
						   00000001b,
						   00000000b,
						   00000000b,
						   00000000b,
						   00000001b,
						   00000001b}

	   char *perm[15][15]={00000000b,
						   00000000b,
						   10000000b,
						   10000000b,
						   00000000b,
						   00000000b,
						   10000000b,
						   10000000b}
		char *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	};
*/

/*#define DEBUG 	*/

#include <stdio.h>

char iperm[16][16][8],fperm[16][16][8];
char s[4][4096];
char p32[4][256][4];
char kn[16][6];				/* 密钥*/

endes(inblock,outblock)			/* 加密一个64-bit块*/
char *inblock, *outblock;
{	char iters[17][8];
	char swap[8];			/* 放置左右交换的值*/
	register int i;
	register char *s, *t;

	permute(inblock,iperm,iters[0]);
	for (i=0; i<16; i++)			/* 完成1~16层的交换*/
		iter(i,iters[i],iters[i+1]);
						/* iters[0][0]~iters[0][8]操作后放到iters[1][0]~iters[1][8]
					iters[1][0]~iters[1][8]操作后放到iters[2][0]~iters[2][8]...以此类推*/
	s = swap; t = &iters[16][4];
	*s++ = *t++; *s++ = *t++; *s++ = *t++; *s++ = *t++;
	t = &iters[16][0];
	*s++ = *t++; *s++ = *t++; *s++ = *t++; *s++ = *t++;
	permute(swap,fperm,outblock);
}

dedes(inblock,outblock)			/* 解密一个64-bit 块*/
char *inblock,*outblock;
{	char iters[17][8];
	char swap[8];
	register int i;
	register char *s, *t;

	permute(inblock,iperm,iters[0]);
	for (i=0; i<16; i++)
		iter(15-i,iters[i],iters[i+1]);

	s = swap; t = &iters[16][4];
	*s++ = *t++; *s++ = *t++; *s++ = *t++; *s++ = *t++;
	t = &iters[16][0];
	*s++ = *t++; *s++ = *t++; *s++ = *t++; *s++ = *t++;
	permute(swap,fperm,outblock);
}

permute(inblock,perm,outblock)		/* 初始换位/最后换位变换*/
char *inblock, *outblock;
char perm[16][16][8];
{	register int i,j;
	register char *ib, *ob;
	register char *p, *q;

	for (i=0, ob = outblock; i<8; i++)
		*ob++ = 0;
	ib = inblock;
	for (j = 0; j < 16; j += 2, ib++)
	{	ob = outblock;
		p = perm[j][(*ib >> 4) & 017];	/*高四位*/
		q = perm[j + 1][*ib & 017];		/*低四位*/
		for (i = 0; i < 8; i++)
			*ob++ |= *p++ | *q++;
		/*-----------------*(ob++)=(*ob)|(*(p++)|*(q++))-----------------*/
	}
}

char ip[]				/* 初始换位表*/
= {	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	};

char fp[]			/* 最后换位表*/
= {	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	};

char pc1[]				/* pc1表*/
= {	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	};

char totrot[]			   /* 密钥生成中的循环左移位的累计次数*/
= {	1,2,4,6,8,10,12,14,15,17,19,21,23,25,27,28	};

char pc1m[56];
char pcr[56];

char pc2[]				/* pc2表*/
= {	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	};

char si[8][64]			  /* 48->32 bit 压缩表*/
= {					/* S[1]			 */
	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,
					/* S[2]			 */
	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,
					/* S[3]			 */
	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,
					/* S[4]			 */
	 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,
					/* S[5]			 */
	 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,
					/* S[6]			 */
	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,
					/* S[7]			 */
	 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,
					/* S[8]			 */
	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	};

char p32i[]				/* 32-bit 单纯换位表*/
= {	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	};

desinit(key)				/* 初始化各种变换矩阵*/
char *key;
{
#ifdef DEBUG
/*deb*/ printf("Initial perm init.\n");
#endif
	perminit(iperm,ip);
#ifdef DEBUG
/*deb*/ printf("Final perm init.\n");
#endif
	perminit(fperm,fp);
#ifdef DEBUG
/*deb*/ printf("Key sched init.\n");
#endif
	kinit(key);	
#ifdef DEBUG
/*deb*/ printf("Compression init.\n");
#endif
	sinit();

#ifdef DEBUG
/*deb*/ printf("32-bit perm init.\n");
#endif
	p32init();
#ifdef DEBUG
/*deb*/ printf("End init.\n");
#endif
}

int bytebit[]
	= {	0200,0100,040,020,010,04,02,01 };

int nibblebit[] = { 010,04,02,01 };

sinit()						 /* 初始化s1-s8矩阵*/
{	register int i,j;

	for (i=0; i<4; i++)		/* 48位按四个12位(一个半字节)来输入*/
		for (j=0; j<4096; j++)
			s[i][j]=(getcomp(i*2,j>>6)<<4) |
				(017&getcomp(i*2+1,j&077));		/*每个s项为一个字节,存有两个体代数*/
}

getcomp(k,v)				/* 用s[k]盒对v进行6bit~4bit的数据压缩*/
int k,v;
{	register int i,j;

	i=((v&040)>>4)|(v&1);			/*i为每个s盒的行号改行号由v的第一位和最后一位组成*/
	j=(v&037)>>1;					/* j位s盒的列号,该列号由v的中间四位组成*/
	return (int) si[k][(i<<4)+j];   /* 返回对v压缩后的值*/
}

kinit(key)				/* 初始化密钥的变换矩阵的中间过渡矩阵*/
char *key;				/* 64 bits */
{	register int i,j,l;
	int m;

	for (j=0; j<56; j++)
	{	l=pc1[j]-1;	
		m = l & 07;
		pc1m[j]=(key[l>>3] & bytebit[m]) ? 1 : 0;
			/*key[l>>3]确定第1位在char key[8]中的哪一个字节中,
						char pc1m[56]是完成pc-1型换位的变换矩阵*/
	}
	for (i=0; i<16; i++)		/* 共生成16个密钥*/
		for (j=0; j<6; j++)		/* 密钥kn的每一个字节*/
			kn[i][j]=0;	
	for (i=0; i<16; i++)
	{	for (j=0; j<56; j++)
		pcr[j] = pc1m[(l=j+totrot[i])<(j<28? 28 : 56) ? l: l-28];
								/* pcr[j]是每次进行循环左移位后的pc1m[]矩阵*/
		for (j=0; j<48; j++)
		if (pcr[pc2[j]-1])
			{	l= j & 07;
				kn[i][j>>3] |= bytebit[l];/*共16个密钥i~[0,16],每个密钥6字节j>>3~[0,5]*/