d3des.c

des加解密实现

#include "d3des.h"

static void scrunch(unsigned char *, unsigned long *);
static void unscrun(unsigned long *, unsigned char *);
static void desfunc(unsigned long *, unsigned long *);
static void cookey(unsigned long *);

static unsigned long KnL[32] = { 0L };
static unsigned long KnR[32] = { 0L };
static unsigned long Kn3[32] = { 0L };
static unsigned char Df_Key[24] = {
	0x01,0x23,0x45,0x67,0x89,0xab,0xcd,0xef,
	0xfe,0xdc,0xba,0x98,0x76,0x54,0x32,0x10,
	0x89,0xab,0xcd,0xef,0x01,0x23,0x45,0x67 };

static unsigned short bytebit[8]	= {
	0200, 0100, 040, 020, 010, 04, 02, 01 };

static unsigned long bigbyte[24] = {
	0x800000L,	0x400000L,	0x200000L,	0x100000L,
	0x80000L,	0x40000L,	0x20000L,	0x10000L,
	0x8000L,	0x4000L,	0x2000L,	0x1000L,
	0x800L, 	0x400L, 	0x200L, 	0x100L,
	0x80L,		0x40L,		0x20L,		0x10L,
	0x8L,		0x4L,		0x2L,		0x1L	};

/* Use the key schedule specified in the Standard (ANSI X3.92-1981). */

static unsigned char pc1[56] = {
	56, 48, 40, 32, 24, 16,  8,	 0, 57, 49, 41, 33, 25, 17,
	 9,  1, 58, 50, 42, 34, 26,	18, 10,  2, 59, 51, 43, 35,
	62, 54, 46, 38, 30, 22, 14,	 6, 61, 53, 45, 37, 29, 21,
	13,  5, 60, 52, 44, 36, 28,	20, 12,  4, 27, 19, 11,  3 };

static unsigned char totrot[16] = {
	1,2,4,6,8,10,12,14,15,17,19,21,23,25,27,28 };

static unsigned char pc2[48] = {
	13, 16, 10, 23,  0,  4,  2, 27, 14,  5, 20,  9,
	22, 18, 11,  3, 25,  7, 15,  6, 26, 19, 12,  1,
	40, 51, 30, 36, 46, 54, 29, 39, 50, 44, 32, 47,
	43, 48, 38, 55, 33, 52, 45, 41, 49, 35, 28, 31 };

void deskey(key, edf)	
unsigned char *key;
short edf;
{
	register int i, j, l, m, n;
	unsigned char pc1m[56], pcr[56];
	unsigned long kn[32];
              /*******************************************************************/
              //key为八位的 数组，如key[8]="abcedfgh",8等于2的3次幂,而每一个字节也是八位，同样8等于2的3次幂
              //所以所有64位只需6位下标就可以全部标识。
              //高三位下标确定是key中的哪一个字符，低三位确定是字符中的哪一位。
              /**********************************************************************************/
	for ( j = 0; j < 56; j++ ) {
		l = pc1[j];//for example l=56 when j=0;
		m = l & 07;  //m为低三位
		pc1m[j] = (key[l >> 3] & bytebit[m]) ? 1 : 0;
		//l>>3确定高三位，bytebit[m]确定要置换的哪一位，两数"与"即为置换。
		}               
	for( i = 0; i < 16; i++ ) {
		if( edf == DE1 ) m = (15 - i) << 1;
		else m = i << 1;
		n = m + 1;
		kn[m] = kn[n] = 0L;
		for( j = 0; j < 28; j++ ) { 
		    //实现循环右移对应位数的操作，前28位作为一个集合。
		    //totrot[i]决定循环右移的位数
			l = j + totrot[i];//if j=0 then l= 0+1 =1 
			                  //if j=27, then l=27+1=28			                   
			if( l < 28 ) pcr[j] = pc1m[l];
			else pcr[j] = pc1m[l - 28];
			}
		for( j = 28; j < 56; j++ ) {
		//实现循环右移对应位数的操作，后28位作为一个集合。
		    l = j + totrot[i];
		    if( l < 56 ) pcr[j] = pc1m[l];
		    else pcr[j] = pc1m[l - 28];
		    }
		for( j = 0; j < 24; j++ ) {
		    //此为一个置换，最终是把56位置换成48位；如果置换后的那一位为1，则密钥中相应的位置1，共形成两个24位的密钥
			if( pcr[pc2[j]] ) kn[m] |= bigbyte[j];
			if( pcr[pc2[j+24]] ) kn[n] |= bigbyte[j];
			}
		}
		//到目前为止形成了32个单元的数组，每个单元如：0X00FFFFFF的形式（此值代表32的long型中只有后24位存放有效数字）
	
	//cookey的最终目的是把两个0x00ffffff形式的long型值变成两个0x3f3f3f3f形式的long型值，即把集中存放的key值分散开来放。
	cookey(kn);
	return;
	}

static void cookey(raw1)
register unsigned long *raw1;
{
	register unsigned long *cook, *raw0;
	unsigned long dough[32];
	register int i;

	cook = dough;
	for( i = 0; i < 16; i++, raw1++ ) {
		//raw0为前24位，raw1为后24位
		raw0 = raw1++;
		*cook	 = (*raw0 & 0x00fc0000L) << 6;
		*cook	|= (*raw0 & 0x00000fc0L) << 10;
		*cook	|= (*raw1 & 0x00fc0000L) >> 10;
		*cook++ |= (*raw1 & 0x00000fc0L) >> 6;
		*cook	 = (*raw0 & 0x0003f000L) << 12;
		*cook	|= (*raw0 & 0x0000003fL) << 16;
		*cook	|= (*raw1 & 0x0003f000L) >> 4;
		*cook++ |= (*raw1 & 0x0000003fL);
		}
		
		//前24位，每六位一组，每组一个标号
		111111(1),111111(5),111111(2),111111(6)
		//后24位，每六位一组，每组一个标号
		111111(3),111111(7),111111(4),111111(8)
		拼成两个32位的串：
		0x3f3f3f3f(组号为1234)
		0x3f3f3f3f(组号为5678)
		
		
		
		
		
	//最终把形成的密钥存放在全局变量KnL中	
	usekey(dough);
	return;
	}

void cpkey(into)
register unsigned long *into;
{
	register unsigned long *from, *endp;

	from = KnL, endp = &KnL[32];
	while( from < endp ) *into++ = *from++;
	return;
	}

void usekey(from)
register unsigned long *from;
{       
        //最终把形成的密钥存放在全局变量KnL中
	register unsigned long *to, *endp;

	to = KnL, endp = &KnL[32];
	while( to < endp ) *to++ = *from++;
	return;
	}

void des(inblock, outblock)
unsigned char *inblock, *outblock;
{
	unsigned long work[2];
         
	scrunch(inblock, work);//该函数的作用是把一个8位字符串4个为一组放到两个long型单元中，long型单元就是数组work
	desfunc(work, KnL);   //实质性的加解密操作，把解密后的信息放回work所指向的空间中。
	unscrun(work, outblock);//把两个long型单元拼成一个八位的字符串
	return;
	}

static void scrunch(outof, into)
register unsigned char *outof;
register unsigned long *into;
{         //outof="abcdefgh"
         //该函数的作用是把一个8位字符串4个为一组放到两个long型单元中
	*into	 = (*outof++ & 0xffL) << 24;
	*into	|= (*outof++ & 0xffL) << 16;
	*into	|= (*outof++ & 0xffL) << 8;
	*into++ |= (*outof++ & 0xffL);
	*into	 = (*outof++ & 0xffL) << 24;
	*into	|= (*outof++ & 0xffL) << 16;
	*into	|= (*outof++ & 0xffL) << 8;
	*into	|= (*outof   & 0xffL);
	return;
	}

static void unscrun(outof, into)
register unsigned long *outof;
register unsigned char *into;
{
	*into++ = (*outof >> 24) & 0xffL;
	*into++ = (*outof >> 16) & 0xffL;
	*into++ = (*outof >>  8) & 0xffL;
	*into++ =  *outof++	 & 0xffL;
	*into++ = (*outof >> 24) & 0xffL;
	*into++ = (*outof >> 16) & 0xffL;
	*into++ = (*outof >>  8) & 0xffL;
	*into	=  *outof	 & 0xffL;
	return;
	}

static unsigned long SP1[64] = {
	0x01010400L, 0x00000000L, 0x00010000L, 0x01010404L,
	0x01010004L, 0x00010404L, 0x00000004L, 0x00010000L,
	0x00000400L, 0x01010400L, 0x01010404L, 0x00000400L,
	0x01000404L, 0x01010004L, 0x01000000L, 0x00000004L,
	0x00000404L, 0x01000400L, 0x01000400L, 0x00010400L,
	0x00010400L, 0x01010000L, 0x01010000L, 0x01000404L,
	0x00010004L, 0x01000004L, 0x01000004L, 0x00010004L,
	0x00000000L, 0x00000404L, 0x00010404L, 0x01000000L,
	0x00010000L, 0x01010404L, 0x00000004L, 0x01010000L,
	0x01010400L, 0x01000000L, 0x01000000L, 0x00000400L,
	0x01010004L, 0x00010000L, 0x00010400L, 0x01000004L,
	0x00000400L, 0x00000004L, 0x01000404L, 0x00010404L,
	0x01010404L, 0x00010004L, 0x01010000L, 0x01000404L,
	0x01000004L, 0x00000404L, 0x00010404L, 0x01010400L,
	0x00000404L, 0x01000400L, 0x01000400L, 0x00000000L,
	0x00010004L, 0x00010400L, 0x00000000L, 0x01010004L };

static unsigned long SP2[64] = {
	0x80108020L, 0x80008000L, 0x00008000L, 0x00108020L,
	0x00100000L, 0x00000020L, 0x80100020L, 0x80008020L,