desc.c

算法源代码比较经典

		/* Chain if decrypting, then update IV. */

		if(context->encrypt == 0) {
			*work ^= *context->iv;
			*(work+1) ^= *(context->iv+1);
			*context->iv = *inputBlock;
			*(context->iv+1) = *(inputBlock+1);
		}else{
			*context->iv = *work;
			*(context->iv+1) = *(work+1);
		}
		unscrunch (&output[8*i], work);
	}

	/* Clear sensitive information. */

	R_memset((POINTER)inputBlock, 0, sizeof(inputBlock));
	R_memset((POINTER)work, 0, sizeof(work));

	return(IDOK);
}

void DES_CBCRestart(context)
DES_CBC_CTX *context;                                                                           /* context */
{
	/* Restore the original IV */

	*context->iv = *context->originalIV;
	*(context->iv+1) = *(context->originalIV+1);
}

/* Initialize context.  Caller should clear the context when finished.
	 The key has the DES key, input whitener and output whitener concatenated.
	 This is the RSADSI special DES implementation.
*/
void DESX_CBCInit(context, key, iv, encrypt)
DESX_CBC_CTX *context;          /* context */
unsigned char *key;             /* DES key and whiteners */
unsigned char *iv;              /* DES initializing vector */
int encrypt;                    /* encrypt flag (1 = encrypt, 0 = decrypt) */
{
	/* Save encrypt flag to context. */

	context->encrypt = encrypt;

	/* Pack initializing vector and whiteners into context. */

	scrunch(context->iv, iv);
	scrunch(context->inputWhitener, key + 8);
	scrunch(context->outputWhitener, key + 16);
	/* Save the IV for use in Restart */
	scrunch(context->originalIV, iv);

	/* Precompute key schedule. */

	deskey (context->subkeys, key, encrypt);
}

/* DESX-CBC block update operation. Continues a DESX-CBC encryption
	 operation, processing eight-byte message blocks, and updating
	 the context.  This is the RSADSI special DES implementation.

	 Requires len to a multiple of 8.
*/

int DESX_CBCUpdate (context, output, input, len)
DESX_CBC_CTX *context;          /* context */
unsigned char *output;          /* output block */
unsigned char *input;           /* input block */
unsigned int len;               /* length of input and output blocks */
{
	UINT4 inputBlock[2], work[2];
	unsigned int i;

	if(len % 8)                                                                             /* Length check */
		return(RE_LEN);

	for(i = 0; i < len/8; i++)  {
		scrunch(inputBlock, &input[8*i]);

		/* Chain if encrypting, and xor with whitener. */

		if(context->encrypt == 0) {
			*work = *inputBlock ^ *context->outputWhitener;
			*(work+1) = *(inputBlock+1) ^ *(context->outputWhitener+1);
		}else{
			*work = *inputBlock ^ *context->iv ^ *context->inputWhitener;
			*(work+1) = *(inputBlock+1) ^ *(context->iv+1) ^ *(context->inputWhitener+1);
		}

		desfunc(work, context->subkeys);

		/* Xor with whitener, chain if decrypting, then update IV. */

		if(context->encrypt == 0) {
			*work ^= *context->iv ^ *context->inputWhitener;
			*(work+1) ^= *(context->iv+1) ^ *(context->inputWhitener+1);
			*(context->iv) = *inputBlock;
			*(context->iv+1) = *(inputBlock+1);
		}else{
			*work ^= *context->outputWhitener;
			*(work+1) ^= *(context->outputWhitener+1);
			*context->iv = *work;
			*(context->iv+1) = *(work+1);
		}
		unscrunch(&output[8*i], work);
	}

	R_memset((POINTER)inputBlock, 0, sizeof(inputBlock));
	R_memset((POINTER)work, 0, sizeof(work));

	return(IDOK);
}

void DESX_CBCRestart(context)
DESX_CBC_CTX *context;          /* context */
{
	/* Restore the original IV */
	*context->iv = *context->originalIV;
	*(context->iv+1) = *(context->originalIV+1);
}

/* Initialize context.  Caller must zeroize the context when finished. */

void DES3_CBCInit(context, key, iv, encrypt)
DES3_CBC_CTX *context;          /* context */
unsigned char *key;             /* key */
unsigned char *iv;              /* initializing vector */
int encrypt;                    /* encrypt flag (1 = encrypt, 0 = decrypt) */
{
	/* Copy encrypt flag to context. */
	context->encrypt = encrypt;

	/* Pack initializing vector into context. */

	scrunch(context->iv, iv);

	/* Save the IV for use in Restart */
	scrunch(context->originalIV, iv);

	/* Precompute key schedules. */

	deskey(context->subkeys[0], encrypt ? key : &key[16], encrypt);
	deskey(context->subkeys[1], &key[8], !encrypt);
	deskey(context->subkeys[2], encrypt ? &key[16] : key, encrypt);
}

int DES3_CBCUpdate(context, output, input, len)
DES3_CBC_CTX *context;          /* context */
unsigned char *output;          /* output block */
unsigned char *input;           /* input block */
unsigned int len;               /* length of input and output blocks */
{
	UINT4 inputBlock[2], work[2];
	unsigned int i;

	if(len % 8)                  /* length check */
		return(RE_LEN);

	for(i = 0; i < len/8; i++) {
		scrunch(inputBlock, &input[8*i]);

		/* Chain if encrypting. */

		if(context->encrypt == 0) {
			*work = *inputBlock;
			*(work+1) = *(inputBlock+1);
		}
		else {
			*work = *inputBlock ^ *context->iv;
			*(work+1) = *(inputBlock+1) ^ *(context->iv+1);
		}

		desfunc(work, context->subkeys[0]);
		desfunc(work, context->subkeys[1]);
		desfunc(work, context->subkeys[2]);

		/* Chain if decrypting, then update IV. */

		if(context->encrypt == 0) {
			*work ^= *context->iv;
			*(work+1) ^= *(context->iv+1);
			*context->iv = *inputBlock;
			*(context->iv+1) = *(inputBlock+1);
		}
		else {
			*context->iv = *work;
			*(context->iv+1) = *(work+1);
		}
		unscrunch(&output[8*i], work);
	}

	R_memset((POINTER)inputBlock, 0, sizeof(inputBlock));
	R_memset((POINTER)work, 0, sizeof(work));

	return (0);
}

void DES3_CBCRestart (context)
DES3_CBC_CTX *context;          /* context */
{
	/* Restore the original IV */
	*context->iv = *context->originalIV;
	*(context->iv+1) = *(context->originalIV+1);
}

void scrunch (into, outof)
UINT4 *into;
unsigned char *outof;
{
	*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);
}

void unscrunch(into, outof)
unsigned char *into;
UINT4 *outof;
{
	*into++ = (unsigned char)((*outof >> 24) & 0xffL);
	*into++ = (unsigned char)((*outof >> 16) & 0xffL);
	*into++ = (unsigned char)((*outof >>  8) & 0xffL);
	*into++ = (unsigned char)( *outof++      & 0xffL);
	*into++ = (unsigned char)((*outof >> 24) & 0xffL);
	*into++ = (unsigned char)((*outof >> 16) & 0xffL);
	*into++ = (unsigned char)((*outof >>  8) & 0xffL);
	*into   = (unsigned char)( *outof        & 0xffL);
}

/* Compute DES Subkeys */

void deskey(subkeys, key, encrypt)
UINT4 subkeys[32];
unsigned char key[8];
int encrypt;
{
	UINT4 kn[32];
	int i, j, l, m, n;
	unsigned char pc1m[56], pcr[56];

	for(j = 0; j < 56; j++) {
		l = pc1[j];
		m = l & 07;
		pc1m[j] = (unsigned char)((key[l >> 3] & bytebit[m]) ? 1 : 0);
	}
	for(i = 0; i < 16; i++) {
		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] = pc1m[l];
			else pcr[j] = pc1m[l - 28];
		}
		for(j = 28; j < 56; j++) {
			l = j + totrot[i];
			if(l < 56) pcr[j] = pc1m[l];
			else pcr[j] = pc1m[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(subkeys, kn, encrypt);

#ifdef DES386
	for(i=0;i < 32;i++)
		subkeys[i] <<= 2;
#endif

	R_memset((POINTER)pc1m, 0, sizeof(pc1m));
	R_memset((POINTER)pcr, 0, sizeof(pcr));
	R_memset((POINTER)kn, 0, sizeof(kn));
}

static void cookey(subkeys, kn, encrypt)
UINT4 *subkeys;
UINT4 *kn;
int encrypt;
{
	UINT4 *cooked, *raw0, *raw1;
	int increment;
	unsigned int i;

	raw1 = kn;
	cooked = encrypt ? subkeys : &subkeys[30];
	increment = encrypt ? 1 : -3;

	for (i = 0; i < 16; i++, raw1++) {
		raw0 = raw1++;
		*cooked    = (*raw0 & 0x00fc0000L) << 6;
		*cooked   |= (*raw0 & 0x00000fc0L) << 10;
		*cooked   |= (*raw1 & 0x00fc0000L) >> 10;
		*cooked++ |= (*raw1 & 0x00000fc0L) >> 6;
		*cooked    = (*raw0 & 0x0003f000L) << 12;
		*cooked   |= (*raw0 & 0x0000003fL) << 16;
		*cooked   |= (*raw1 & 0x0003f000L) >> 4;
		*cooked   |= (*raw1 & 0x0000003fL);
		cooked += increment;
	}
}

#ifndef DES386 /* ignore C version in favor of 386 ONLY desfunc */

#define	F(l,r,key){\
	work = ((r >> 4) | (r << 28)) ^ *key;\
	l ^= Spbox[6][work & 0x3f];\
	l ^= Spbox[4][(work >> 8) & 0x3f];\
	l ^= Spbox[2][(work >> 16) & 0x3f];\
	l ^= Spbox[0][(work >> 24) & 0x3f];\
	work = r ^ *(key+1);\
	l ^= Spbox[7][work & 0x3f];\
	l ^= Spbox[5][(work >> 8) & 0x3f];\
	l ^= Spbox[3][(work >> 16) & 0x3f];\
	l ^= Spbox[1][(work >> 24) & 0x3f];\
}

/* This desfunc code is marginally quicker than that uses in
	 RSAREF(tm)
*/

void desfunc(block,ks)
UINT4 *block;		/* Data block */
UINT4 *ks;	/* Key schedule */
{
	unsigned long left,right,work;

	left = block[0];
	right = block[1];

	work = ((left >> 4) ^ right) & 0x0f0f0f0f;
	right ^= work;
	left ^= work << 4;
	work = ((left >> 16) ^ right) & 0xffff;
	right ^= work;
	left ^= work << 16;
	work = ((right >> 2) ^ left) & 0x33333333;
	left ^= work;
	right ^= (work << 2);
	work = ((right >> 8) ^ left) & 0xff00ff;
	left ^= work;
	right ^= (work << 8);
	right = (right << 1) | (right >> 31);
	work = (left ^ right) & 0xaaaaaaaa;
	left ^= work;
	right ^= work;
	left = (left << 1) | (left >> 31);

	/* Now do the 16 rounds */
	F(left,right,&ks[0]);
	F(right,left,&ks[2]);
	F(left,right,&ks[4]);
	F(right,left,&ks[6]);
	F(left,right,&ks[8]);
	F(right,left,&ks[10]);
	F(left,right,&ks[12]);
	F(right,left,&ks[14]);
	F(left,right,&ks[16]);
	F(right,left,&ks[18]);
	F(left,right,&ks[20]);
	F(right,left,&ks[22]);
	F(left,right,&ks[24]);
	F(right,left,&ks[26]);
	F(left,right,&ks[28]);
	F(right,left,&ks[30]);

	right = (right << 31) | (right >> 1);
	work = (left ^ right) & 0xaaaaaaaa;
	left ^= work;
	right ^= work;
	left = (left >> 1) | (left  << 31);
	work = ((left >> 8) ^ right) & 0xff00ff;
	right ^= work;
	left ^= work << 8;
	work = ((left >> 2) ^ right) & 0x33333333;
	right ^= work;
	left ^= work << 2;
	work = ((right >> 16) ^ left) & 0xffff;
	left ^= work;
	right ^= work << 16;
	work = ((right >> 4) ^ left) & 0x0f0f0f0f;
	left ^= work;
	right ^= work << 4;

	*block++ = right;
	*block = left;
}

#endif /* DES386 endif */