des.c

在原作者Jim Gillogly代码的基础上修改优化

/* 
 * Guanlan,2007.5.25
 * It is proved again that it's very important to add comment for source code!!
 * Here i just give the interface of some important function.
 * 1.void des_key(des_ctx *dc,unsignd char *key),provides the key of enc (dc->ek) and 
 * 	 dec (dc->dk) respectively.
 * 2.void des_enc(des_ctx *dc,unsigned char *data,int blocks),use the key dc->ek to 
 *   encrypt data. Each block has 8 bytes data.The cipher placed in data instead of plain. 
 * 3.void des_dec(des_ctx *dc,unsigned char *data,int blocks),use the key dc->dk to 
 *   decrypt data.The plain placed in  data instead of cipher.
 */
#define EN0 0
#define DE1 1

typedef struct
{
	unsigned long ek[32];
	unsigned long dk[32];
}des_ctx;

extern void deskey(unsigned char *,short);
extern void usekey(unsigned long *);
extern void cpkey(unsigned long *);
extern void des(unsigned char *,unsigned char *);

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,	0x2000L,	0x10000L,
	0x8000L,	0x4000L,	0x200L,		0x1000L,
	0x800L,		0x400L,		0x20L,		0x100L,
	0x80L,		0x40L,		0x20L,		0x10L,
	0x8L,		0x4L,		0x2L,		0x1L
};

static unsigned char pcl[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(unsigned char *key,short edf)
{
	register int i,j,l,m,n;
	unsigned char pclm[56],pcr[56];
	unsigned long kn[32];

	for(j=0;j<56;j++)
	{
		l = pcl[j];
		m = l&07;
		pclm[j] = (key[l>>3] & bytebit[m])? 1:0;
	}

	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++)
		{
			l=j+totrot[i];
			if(l<28)
				pcr[j] = pclm[l];
			else
				pcr[j] = pclm[l-28];
		}
		for(j=28;j<56;j++)
		{
			l=j+totrot[i];
			if(l<56)
				pcr[j] = pclm[l];
			else
				pcr[j] = pclm[l-28];
		}

		for(j=0;j<24;j++)
		{
			if(pcr[pc2[j]])
				kn[m] |= bigbyte[j];
			if(pcr[pc2[j+24]])
				kn[n] |= bigbyte[j];
		}
	}
	cookey(kn);
	return;
}

static void cookey(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 = 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) ;
	}
	usekey(dough);
	return;
}

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

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

void usekey(register unsigned long *from)
{
	register unsigned long *to,*endp;
	
	to = KnL,endp = &KnL[32];
	while(to<endp)
		*to++ = *from++;
	return;
}

void des(unsigned char *inblock,unsigned char *outblock)
{
	unsigned long work[2];

	scrunch(inblock,work);
	desfunc(work,KnL);
	unscrun(work,outblock);
	return;
}

static void scrunch(register unsigned char *outof,register unsigned long *into)
{
	*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(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, 
   0x80000020L, 0x80108020L, 0x80108000L, 0x80000000L,
   0x80008000L, 0x00100000L, 0x00000020L, 0x80100020L, 
   0x00108000L, 0x00100020L, 0x80008020L, 0x00000000L,
   0x80000000L, 0x00008000L, 0x00108020L, 0x80100000L, 
   0x00100020L, 0x80000020L, 0x00000000L, 0x00108000L,
   0x00008020L, 0x80108000L, 0x80100000L, 0x00008020L,
   0x00000000L, 0x00108020L, 0x80100020L, 0x00100000L,
   0x80008020L, 0x80100000L, 0x80108000L, 0x00008000L, 
   0x80100000L, 0x80008000L, 0x00000020L, 0x80108020L,
   0x00108020L, 0x00000020L, 0x00008000L, 0x80000000L,
   0x00008020L, 0x80108000L, 0x00100000L, 0x80000020L,
   0x00100020L, 0x80008020L, 0x80000020L, 0x00100020L,
   0x00108000L, 0x00000000L, 0x80008000L, 0x00008020L,
   0x80000000L, 0x80100020L, 0x80108020L, 0x00108000L 
};  

static unsigned long SP3[64] = {   
   0x00000208L, 0x08020200L, 0x00000000L, 0x08020008L,  
   0x08000200L, 0x00000000L, 0x00020208L, 0x08000200L, 
   0x00020008L, 0x08000008L, 0x08000008L, 0x00020000L,
   0x08020208L, 0x00020008L, 0x08020000L, 0x00000208L, 
   0x08000000L, 0x00000008L, 0x08020200L, 0x00000200L, 
   0x00020200L, 0x08020000L, 0x08020008L, 0x00020208L, 
   0x08000208L, 0x00020200L, 0x00020000L, 0x08000208L,
   0x00000008L, 0x08020208L, 0x00000200L, 0x08000000L,
   0x08020200L, 0x08000000L, 0x00020008L, 0x00000208L, 
   0x00020000L, 0x08020200L, 0x08000200L, 0x00000000L, 
   0x00000200L, 0x00020008L, 0x08020208L, 0x08000200L,