bn_nist.c

openssl

#define nist_set_224(to, from, a1, a2, a3, a4, a5, a6, a7) \
	{ \
	bn_cp_32(to, 0, from, (a7) - 7) \
	bn_cp_32(to, 1, from, (a6) - 7) \
	bn_cp_32(to, 2, from, (a5) - 7) \
	bn_cp_32(to, 3, from, (a4) - 7) \
	bn_cp_32(to, 4, from, (a3) - 7) \
	bn_cp_32(to, 5, from, (a2) - 7) \
	bn_cp_32(to, 6, from, (a1) - 7) \
	}

int BN_nist_mod_224(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
	BN_CTX *ctx)
	{
	int	top = a->top, i;
	int	carry;
	BN_ULONG *r_d, *a_d = a->d;
	BN_ULONG t_d[BN_NIST_224_TOP],
	         buf[BN_NIST_224_TOP],
		 c_d[BN_NIST_224_TOP],
		*res;
	size_t   mask;
	union { bn_addsub_f f; size_t p; } u;
	static const BIGNUM _bignum_nist_p_224_sqr = {
		(BN_ULONG *)_nist_p_224_sqr,
		sizeof(_nist_p_224_sqr)/sizeof(_nist_p_224_sqr[0]),
		sizeof(_nist_p_224_sqr)/sizeof(_nist_p_224_sqr[0]),
		0,BN_FLG_STATIC_DATA };


	field = &_bignum_nist_p_224; /* just to make sure */

 	if (BN_is_negative(a) || BN_ucmp(a,&_bignum_nist_p_224_sqr)>=0)
		return BN_nnmod(r, a, field, ctx);

	i = BN_ucmp(field, a);
	if (i == 0)
		{
		BN_zero(r);
		return 1;
		}
	else if (i > 0)
		return (r == a)? 1 : (BN_copy(r ,a) != NULL);

	if (r != a)
		{
		if (!bn_wexpand(r, BN_NIST_224_TOP))
			return 0;
		r_d = r->d;
		nist_cp_bn(r_d, a_d, BN_NIST_224_TOP);
		}
	else
		r_d = a_d;

#if BN_BITS2==64
	/* copy upper 256 bits of 448 bit number ... */
	nist_cp_bn_0(t_d, a_d + (BN_NIST_224_TOP-1), top - (BN_NIST_224_TOP-1), BN_NIST_224_TOP);
	/* ... and right shift by 32 to obtain upper 224 bits */
	nist_set_224(buf, t_d, 14, 13, 12, 11, 10, 9, 8);
	/* truncate lower part to 224 bits too */
	r_d[BN_NIST_224_TOP-1] &= BN_MASK2l;
#else
	nist_cp_bn_0(buf, a_d + BN_NIST_224_TOP, top - BN_NIST_224_TOP, BN_NIST_224_TOP);
#endif
	nist_set_224(t_d, buf, 10, 9, 8, 7, 0, 0, 0);
	carry = (int)bn_add_words(r_d, r_d, t_d, BN_NIST_224_TOP);
	nist_set_224(t_d, buf, 0, 13, 12, 11, 0, 0, 0);
	carry += (int)bn_add_words(r_d, r_d, t_d, BN_NIST_224_TOP);
	nist_set_224(t_d, buf, 13, 12, 11, 10, 9, 8, 7);
	carry -= (int)bn_sub_words(r_d, r_d, t_d, BN_NIST_224_TOP);
	nist_set_224(t_d, buf, 0, 0, 0, 0, 13, 12, 11);
	carry -= (int)bn_sub_words(r_d, r_d, t_d, BN_NIST_224_TOP);

#if BN_BITS2==64
	carry = (int)(r_d[BN_NIST_224_TOP-1]>>32);
#endif
	u.f = bn_sub_words;
	if (carry > 0)
		{
		carry = (int)bn_sub_words(r_d,r_d,_nist_p_224[carry-1],BN_NIST_224_TOP);
#if BN_BITS2==64
		carry=(int)(~(r_d[BN_NIST_224_TOP-1]>>32))&1;
#endif
		}
	else if (carry < 0)
		{
		/* it's a bit more comlicated logic in this case.
		 * if bn_add_words yields no carry, then result
		 * has to be adjusted by unconditionally *adding*
		 * the modulus. but if it does, then result has
		 * to be compared to the modulus and conditionally
		 * adjusted by *subtracting* the latter. */
		carry = (int)bn_add_words(r_d,r_d,_nist_p_224[-carry-1],BN_NIST_224_TOP);
		mask = 0-(size_t)carry;
		u.p = ((size_t)bn_sub_words&mask) | ((size_t)bn_add_words&~mask);
		}
	else
		carry = 1;

	/* otherwise it's effectively same as in BN_nist_mod_192... */
	mask  = 0-(size_t)(*u.f)(c_d,r_d,_nist_p_224[0],BN_NIST_224_TOP);
	mask &= 0-(size_t)carry;
	res   = (BN_ULONG *)(((size_t)c_d&~mask) | ((size_t)r_d&mask));
	nist_cp_bn(r_d, res, BN_NIST_224_TOP);
	r->top = BN_NIST_224_TOP;
	bn_correct_top(r);

	return 1;
	}

#define nist_set_256(to, from, a1, a2, a3, a4, a5, a6, a7, a8) \
	{ \
	bn_cp_32(to, 0, from, (a8) - 8) \
	bn_cp_32(to, 1, from, (a7) - 8) \
	bn_cp_32(to, 2, from, (a6) - 8) \
	bn_cp_32(to, 3, from, (a5) - 8) \
	bn_cp_32(to, 4, from, (a4) - 8) \
	bn_cp_32(to, 5, from, (a3) - 8) \
	bn_cp_32(to, 6, from, (a2) - 8) \
	bn_cp_32(to, 7, from, (a1) - 8) \
	}

int BN_nist_mod_256(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
	BN_CTX *ctx)
	{
	int	i, top = a->top;
	int	carry = 0;
	register BN_ULONG *a_d = a->d, *r_d;
	BN_ULONG t_d[BN_NIST_256_TOP],
	         buf[BN_NIST_256_TOP],
		 c_d[BN_NIST_256_TOP],
		*res;
	size_t   mask;
	union { bn_addsub_f f; size_t p; } u;
	static const BIGNUM _bignum_nist_p_256_sqr = {
		(BN_ULONG *)_nist_p_256_sqr,
		sizeof(_nist_p_256_sqr)/sizeof(_nist_p_256_sqr[0]),
		sizeof(_nist_p_256_sqr)/sizeof(_nist_p_256_sqr[0]),
		0,BN_FLG_STATIC_DATA };

	field = &_bignum_nist_p_256; /* just to make sure */

 	if (BN_is_negative(a) || BN_ucmp(a,&_bignum_nist_p_256_sqr)>=0)
		return BN_nnmod(r, a, field, ctx);

	i = BN_ucmp(field, a);
	if (i == 0)
		{
		BN_zero(r);
		return 1;
		}
	else if (i > 0)
		return (r == a)? 1 : (BN_copy(r ,a) != NULL);

	if (r != a)
		{
		if (!bn_wexpand(r, BN_NIST_256_TOP))
			return 0;
		r_d = r->d;
		nist_cp_bn(r_d, a_d, BN_NIST_256_TOP);
		}
	else
		r_d = a_d;

	nist_cp_bn_0(buf, a_d + BN_NIST_256_TOP, top - BN_NIST_256_TOP, BN_NIST_256_TOP);

	/*S1*/
	nist_set_256(t_d, buf, 15, 14, 13, 12, 11, 0, 0, 0);
	/*S2*/
	nist_set_256(c_d, buf, 0, 15, 14, 13, 12, 0, 0, 0);
	carry = (int)bn_add_words(t_d, t_d, c_d, BN_NIST_256_TOP);
	/* left shift */
		{
		register BN_ULONG *ap,t,c;
		ap = t_d;
		c=0;
		for (i = BN_NIST_256_TOP; i != 0; --i)
			{
			t= *ap;
			*(ap++)=((t<<1)|c)&BN_MASK2;
			c=(t & BN_TBIT)?1:0;
			}
		carry <<= 1;
		carry  |= c;
		}
	carry += (int)bn_add_words(r_d, r_d, t_d, BN_NIST_256_TOP);
	/*S3*/
	nist_set_256(t_d, buf, 15, 14, 0, 0, 0, 10, 9, 8);
	carry += (int)bn_add_words(r_d, r_d, t_d, BN_NIST_256_TOP);
	/*S4*/
	nist_set_256(t_d, buf, 8, 13, 15, 14, 13, 11, 10, 9);
	carry += (int)bn_add_words(r_d, r_d, t_d, BN_NIST_256_TOP);
	/*D1*/
	nist_set_256(t_d, buf, 10, 8, 0, 0, 0, 13, 12, 11);
	carry -= (int)bn_sub_words(r_d, r_d, t_d, BN_NIST_256_TOP);
	/*D2*/
	nist_set_256(t_d, buf, 11, 9, 0, 0, 15, 14, 13, 12);
	carry -= (int)bn_sub_words(r_d, r_d, t_d, BN_NIST_256_TOP);
	/*D3*/
	nist_set_256(t_d, buf, 12, 0, 10, 9, 8, 15, 14, 13);
	carry -= (int)bn_sub_words(r_d, r_d, t_d, BN_NIST_256_TOP);
	/*D4*/
	nist_set_256(t_d, buf, 13, 0, 11, 10, 9, 0, 15, 14);
	carry -= (int)bn_sub_words(r_d, r_d, t_d, BN_NIST_256_TOP);

	/* see BN_nist_mod_224 for explanation */
	u.f = bn_sub_words;
	if (carry > 0)
		carry = (int)bn_sub_words(r_d,r_d,_nist_p_256[carry-1],BN_NIST_256_TOP);
	else if (carry < 0)
		{
		carry = (int)bn_add_words(r_d,r_d,_nist_p_256[-carry-1],BN_NIST_256_TOP);
		mask = 0-(size_t)carry;
		u.p = ((size_t)bn_sub_words&mask) | ((size_t)bn_add_words&~mask);
		}
	else
		carry = 1;

	mask  = 0-(size_t)(*u.f)(c_d,r_d,_nist_p_256[0],BN_NIST_256_TOP);
	mask &= 0-(size_t)carry;
	res   = (BN_ULONG *)(((size_t)c_d&~mask) | ((size_t)r_d&mask));
	nist_cp_bn(r_d, res, BN_NIST_256_TOP);
	r->top = BN_NIST_256_TOP;
	bn_correct_top(r);

	return 1;
	}

#define nist_set_384(to,from,a1,a2,a3,a4,a5,a6,a7,a8,a9,a10,a11,a12) \
	{ \
	bn_cp_32(to, 0, from,  (a12) - 12) \
	bn_cp_32(to, 1, from,  (a11) - 12) \
	bn_cp_32(to, 2, from,  (a10) - 12) \
	bn_cp_32(to, 3, from,  (a9) - 12)  \
	bn_cp_32(to, 4, from,  (a8) - 12)  \
	bn_cp_32(to, 5, from,  (a7) - 12)  \
	bn_cp_32(to, 6, from,  (a6) - 12)  \
	bn_cp_32(to, 7, from,  (a5) - 12)  \
	bn_cp_32(to, 8, from,  (a4) - 12)  \
	bn_cp_32(to, 9, from,  (a3) - 12)  \
	bn_cp_32(to, 10, from, (a2) - 12)  \
	bn_cp_32(to, 11, from, (a1) - 12)  \
	}

int BN_nist_mod_384(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
	BN_CTX *ctx)
	{
	int	i, top = a->top;
	int	carry = 0;
	register BN_ULONG *r_d, *a_d = a->d;
	BN_ULONG t_d[BN_NIST_384_TOP],
	         buf[BN_NIST_384_TOP],
		 c_d[BN_NIST_384_TOP],
		*res;
	size_t	 mask;
	union { bn_addsub_f f; size_t p; } u;
	static const BIGNUM _bignum_nist_p_384_sqr = {
		(BN_ULONG *)_nist_p_384_sqr,
		sizeof(_nist_p_384_sqr)/sizeof(_nist_p_384_sqr[0]),
		sizeof(_nist_p_384_sqr)/sizeof(_nist_p_384_sqr[0]),
		0,BN_FLG_STATIC_DATA };


	field = &_bignum_nist_p_384; /* just to make sure */

 	if (BN_is_negative(a) || BN_ucmp(a,&_bignum_nist_p_384_sqr)>=0)
		return BN_nnmod(r, a, field, ctx);

	i = BN_ucmp(field, a);
	if (i == 0)
		{
		BN_zero(r);
		return 1;
		}
	else if (i > 0)
		return (r == a)? 1 : (BN_copy(r ,a) != NULL);

	if (r != a)
		{
		if (!bn_wexpand(r, BN_NIST_384_TOP))
			return 0;
		r_d = r->d;
		nist_cp_bn(r_d, a_d, BN_NIST_384_TOP);
		}
	else
		r_d = a_d;

	nist_cp_bn_0(buf, a_d + BN_NIST_384_TOP, top - BN_NIST_384_TOP, BN_NIST_384_TOP);

	/*S1*/
	nist_set_256(t_d, buf, 0, 0, 0, 0, 0, 23-4, 22-4, 21-4);
		/* left shift */
		{
		register BN_ULONG *ap,t,c;
		ap = t_d;
		c=0;
		for (i = 3; i != 0; --i)
			{
			t= *ap;
			*(ap++)=((t<<1)|c)&BN_MASK2;
			c=(t & BN_TBIT)?1:0;
			}
		*ap=c;
		}
	carry = (int)bn_add_words(r_d+(128/BN_BITS2), r_d+(128/BN_BITS2), 
		t_d, BN_NIST_256_TOP);
	/*S2 */
	carry += (int)bn_add_words(r_d, r_d, buf, BN_NIST_384_TOP);
	/*S3*/
	nist_set_384(t_d,buf,20,19,18,17,16,15,14,13,12,23,22,21);
	carry += (int)bn_add_words(r_d, r_d, t_d, BN_NIST_384_TOP);
	/*S4*/
	nist_set_384(t_d,buf,19,18,17,16,15,14,13,12,20,0,23,0);
	carry += (int)bn_add_words(r_d, r_d, t_d, BN_NIST_384_TOP);
	/*S5*/
	nist_set_384(t_d, buf,0,0,0,0,23,22,21,20,0,0,0,0);
	carry += (int)bn_add_words(r_d, r_d, t_d, BN_NIST_384_TOP);
	/*S6*/
	nist_set_384(t_d,buf,0,0,0,0,0,0,23,22,21,0,0,20);
	carry += (int)bn_add_words(r_d, r_d, t_d, BN_NIST_384_TOP);
	/*D1*/
	nist_set_384(t_d,buf,22,21,20,19,18,17,16,15,14,13,12,23);
	carry -= (int)bn_sub_words(r_d, r_d, t_d, BN_NIST_384_TOP);
	/*D2*/
	nist_set_384(t_d,buf,0,0,0,0,0,0,0,23,22,21,20,0);
	carry -= (int)bn_sub_words(r_d, r_d, t_d, BN_NIST_384_TOP);
	/*D3*/
	nist_set_384(t_d,buf,0,0,0,0,0,0,0,23,23,0,0,0);
	carry -= (int)bn_sub_words(r_d, r_d, t_d, BN_NIST_384_TOP);

	/* see BN_nist_mod_224 for explanation */
	u.f = bn_sub_words;
	if (carry > 0)
		carry = (int)bn_sub_words(r_d,r_d,_nist_p_384[carry-1],BN_NIST_384_TOP);
	else if (carry < 0)
		{
		carry = (int)bn_add_words(r_d,r_d,_nist_p_384[-carry-1],BN_NIST_384_TOP);
		mask = 0-(size_t)carry;
		u.p = ((size_t)bn_sub_words&mask) | ((size_t)bn_add_words&~mask);
		}
	else
		carry = 1;

	mask  = 0-(size_t)(*u.f)(c_d,r_d,_nist_p_384[0],BN_NIST_384_TOP);
	mask &= 0-(size_t)carry;
	res   = (BN_ULONG *)(((size_t)c_d&~mask) | ((size_t)r_d&mask));
	nist_cp_bn(r_d, res, BN_NIST_384_TOP);
	r->top = BN_NIST_384_TOP;
	bn_correct_top(r);

	return 1;
	}

#define BN_NIST_521_RSHIFT	(521%BN_BITS2)
#define BN_NIST_521_LSHIFT	(BN_BITS2-BN_NIST_521_RSHIFT)
#define BN_NIST_521_TOP_MASK	((BN_ULONG)BN_MASK2>>BN_NIST_521_LSHIFT)

int BN_nist_mod_521(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
	BN_CTX *ctx)
	{
	int	top = a->top, i;
	BN_ULONG *r_d, *a_d = a->d,
		 t_d[BN_NIST_521_TOP],
		 val,tmp,*res;
	size_t	mask;
	static const BIGNUM _bignum_nist_p_521_sqr = {
		(BN_ULONG *)_nist_p_521_sqr,
		sizeof(_nist_p_521_sqr)/sizeof(_nist_p_521_sqr[0]),
		sizeof(_nist_p_521_sqr)/sizeof(_nist_p_521_sqr[0]),
		0,BN_FLG_STATIC_DATA };

	field = &_bignum_nist_p_521; /* just to make sure */

 	if (BN_is_negative(a) || BN_ucmp(a,&_bignum_nist_p_521_sqr)>=0)
		return BN_nnmod(r, a, field, ctx);

	i = BN_ucmp(field, a);
	if (i == 0)
		{
		BN_zero(r);
		return 1;
		}
	else if (i > 0)
		return (r == a)? 1 : (BN_copy(r ,a) != NULL);

	if (r != a)
		{
		if (!bn_wexpand(r,BN_NIST_521_TOP))
			return 0;
		r_d = r->d;
		nist_cp_bn(r_d,a_d, BN_NIST_521_TOP);
		}
	else
		r_d = a_d;

	/* upper 521 bits, copy ... */
	nist_cp_bn_0(t_d,a_d + (BN_NIST_521_TOP-1), top - (BN_NIST_521_TOP-1),BN_NIST_521_TOP);
	/* ... and right shift */
	for (val=t_d[0],i=0; i<BN_NIST_521_TOP-1; i++)
		{
		tmp = val>>BN_NIST_521_RSHIFT;
		val = t_d[i+1];
		t_d[i] = (tmp | val<<BN_NIST_521_LSHIFT) & BN_MASK2;
		}
	t_d[i] = val>>BN_NIST_521_RSHIFT;
	/* lower 521 bits */
	r_d[i] &= BN_NIST_521_TOP_MASK;

	bn_add_words(r_d,r_d,t_d,BN_NIST_521_TOP);
	mask = 0-(size_t)bn_sub_words(t_d,r_d,_nist_p_521,BN_NIST_521_TOP);
	res  = (BN_ULONG *)(((size_t)t_d&~mask) | ((size_t)r_d&mask));
	nist_cp_bn(r_d,res,BN_NIST_521_TOP);
	r->top = BN_NIST_521_TOP;
	bn_correct_top(r);

	return 1;
	}