bn_nist.c

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	else if (carry < 0)
		while (carry)
			{
			if (bn_add_words(r_d,r_d,_nist_p_224,BN_NIST_224_TOP))
				++carry;
			}

	r->top = BN_NIST_224_TOP;
	bn_correct_top(r);
	if (BN_ucmp(r, field) >= 0)
		{
		bn_sub_words(r_d, r_d, _nist_p_224, BN_NIST_224_TOP);
		bn_correct_top(r);
		}
	bn_check_top(r);
	return 1;
#else
	return 0;
#endif
	}

#if BN_BITS2 != 64
static void _init_256_data(void)
	{
	int	i;
	BN_ULONG *tmp1 = _256_data;
	const BN_ULONG *tmp2 = tmp1;

	memcpy(tmp1, _nist_p_256, BN_NIST_256_TOP * sizeof(BN_ULONG));
	tmp1 += BN_NIST_256_TOP;

	for (i=0; i<5; i++)
		{
		bn_add_words(tmp1, _nist_p_256, tmp2, BN_NIST_256_TOP);
		tmp2  = tmp1;
		tmp1 += BN_NIST_256_TOP;
		}
	_is_set_256_data = 1;
	}
#endif

#define nist_set_256(to, from, a1, a2, a3, a4, a5, a6, a7, a8) \
	{ \
	if (a8 != 0) bn_cp_32(to, 0, from, (a8) - 8) else bn_32_set_0(to, 0)\
	if (a7 != 0) bn_cp_32(to, 1, from, (a7) - 8) else bn_32_set_0(to, 1)\
	if (a6 != 0) bn_cp_32(to, 2, from, (a6) - 8) else bn_32_set_0(to, 2)\
	if (a5 != 0) bn_cp_32(to, 3, from, (a5) - 8) else bn_32_set_0(to, 3)\
	if (a4 != 0) bn_cp_32(to, 4, from, (a4) - 8) else bn_32_set_0(to, 4)\
	if (a3 != 0) bn_cp_32(to, 5, from, (a3) - 8) else bn_32_set_0(to, 5)\
	if (a2 != 0) bn_cp_32(to, 6, from, (a2) - 8) else bn_32_set_0(to, 6)\
	if (a1 != 0) bn_cp_32(to, 7, from, (a1) - 8) else bn_32_set_0(to, 7)\
	}

int BN_nist_mod_256(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
	BN_CTX *ctx)
	{
#if BN_BITS2 != 64
	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],
	         t_d2[BN_NIST_256_TOP],
	         buf[BN_NIST_256_TOP];

	if (!_is_set_256_data)
		{
		CRYPTO_w_lock(CRYPTO_LOCK_BN);
		
		if (!_is_set_256_data)
			_init_256_data();
		
		CRYPTO_w_unlock(CRYPTO_LOCK_BN);
		}
	
	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 (top == BN_NIST_256_TOP)
		return BN_usub(r, a, field);

	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(t_d2,buf, 0, 15, 14, 13, 12, 0, 0, 0);
	if (bn_add_words(t_d, t_d, t_d2, BN_NIST_256_TOP))
		carry = 2;
	/* 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;
			}
		if (c)
			++carry;
		}

	if (bn_add_words(r_d, r_d, t_d, BN_NIST_256_TOP))
		++carry;
	/*S3*/
	nist_set_256(t_d, buf, 15, 14, 0, 0, 0, 10, 9, 8);
	if (bn_add_words(r_d, r_d, t_d, BN_NIST_256_TOP))
		++carry;
	/*S4*/
	nist_set_256(t_d, buf, 8, 13, 15, 14, 13, 11, 10, 9);
	if (bn_add_words(r_d, r_d, t_d, BN_NIST_256_TOP))
		++carry;
	/*D1*/
	nist_set_256(t_d, buf, 10, 8, 0, 0, 0, 13, 12, 11);
	if (bn_sub_words(r_d, r_d, t_d, BN_NIST_256_TOP))
		--carry;
	/*D2*/
	nist_set_256(t_d, buf, 11, 9, 0, 0, 15, 14, 13, 12);
	if (bn_sub_words(r_d, r_d, t_d, BN_NIST_256_TOP))
		--carry;
	/*D3*/
	nist_set_256(t_d, buf, 12, 0, 10, 9, 8, 15, 14, 13);
	if (bn_sub_words(r_d, r_d, t_d, BN_NIST_256_TOP))
		--carry;
	/*D4*/
	nist_set_256(t_d, buf, 13, 0, 11, 10, 9, 0, 15, 14);
	if (bn_sub_words(r_d, r_d, t_d, BN_NIST_256_TOP))
		--carry;
	
	if (carry)
		{
		if (carry > 0)
			bn_sub_words(r_d, r_d, _256_data + BN_NIST_256_TOP *
				--carry, BN_NIST_256_TOP);
		else
			{
			carry = -carry;
			bn_add_words(r_d, r_d, _256_data + BN_NIST_256_TOP *
				--carry, BN_NIST_256_TOP);
			}
		}

	r->top = BN_NIST_256_TOP;
	bn_correct_top(r);
	if (BN_ucmp(r, field) >= 0)
		{
		bn_sub_words(r_d, r_d, _nist_p_256, BN_NIST_256_TOP);
		bn_correct_top(r);
		}
	bn_check_top(r);
	return 1;
#else
	return 0;
#endif
	}

#if BN_BITS2 != 64
static void _init_384_data(void)
	{
	int	i;
	BN_ULONG *tmp1 = _384_data;
	const BN_ULONG *tmp2 = tmp1;

	memcpy(tmp1, _nist_p_384, BN_NIST_384_TOP * sizeof(BN_ULONG));
	tmp1 += BN_NIST_384_TOP;

	for (i=0; i<7; i++)
		{
		bn_add_words(tmp1, _nist_p_384, tmp2, BN_NIST_384_TOP);
		tmp2  = tmp1;
		tmp1 += BN_NIST_384_TOP;
		}
	_is_set_384_data = 1;
	}
#endif

#define nist_set_384(to,from,a1,a2,a3,a4,a5,a6,a7,a8,a9,a10,a11,a12) \
	{ \
	if (a12 != 0) bn_cp_32(to, 0, from,  (a12) - 12) else bn_32_set_0(to, 0)\
	if (a11 != 0) bn_cp_32(to, 1, from,  (a11) - 12) else bn_32_set_0(to, 1)\
	if (a10 != 0) bn_cp_32(to, 2, from,  (a10) - 12) else bn_32_set_0(to, 2)\
	if (a9 != 0)  bn_cp_32(to, 3, from,  (a9) - 12)  else bn_32_set_0(to, 3)\
	if (a8 != 0)  bn_cp_32(to, 4, from,  (a8) - 12)  else bn_32_set_0(to, 4)\
	if (a7 != 0)  bn_cp_32(to, 5, from,  (a7) - 12)  else bn_32_set_0(to, 5)\
	if (a6 != 0)  bn_cp_32(to, 6, from,  (a6) - 12)  else bn_32_set_0(to, 6)\
	if (a5 != 0)  bn_cp_32(to, 7, from,  (a5) - 12)  else bn_32_set_0(to, 7)\
	if (a4 != 0)  bn_cp_32(to, 8, from,  (a4) - 12)  else bn_32_set_0(to, 8)\
	if (a3 != 0)  bn_cp_32(to, 9, from,  (a3) - 12)  else bn_32_set_0(to, 9)\
	if (a2 != 0)  bn_cp_32(to, 10, from, (a2) - 12)  else bn_32_set_0(to, 10)\
	if (a1 != 0)  bn_cp_32(to, 11, from, (a1) - 12)  else bn_32_set_0(to, 11)\
	}

int BN_nist_mod_384(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
	BN_CTX *ctx)
	{
#if BN_BITS2 != 64
	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];

	if (!_is_set_384_data)
		{
		CRYPTO_w_lock(CRYPTO_LOCK_BN);
		
		if (!_is_set_384_data)
			_init_384_data();

		CRYPTO_w_unlock(CRYPTO_LOCK_BN);
		}

	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 (top == BN_NIST_384_TOP)
		return BN_usub(r, a, field);

	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 = BN_NIST_256_TOP; i != 0; --i)
			{
			t= *ap;
			*(ap++)=((t<<1)|c)&BN_MASK2;
			c=(t & BN_TBIT)?1:0;
			}
		}
	if (bn_add_words(r_d+(128/BN_BITS2), r_d+(128/BN_BITS2), 
		t_d, BN_NIST_256_TOP))
		++carry;
	/*S2 */
	if (bn_add_words(r_d, r_d, buf, BN_NIST_384_TOP))
		++carry;
	/*S3*/
	nist_set_384(t_d,buf,20,19,18,17,16,15,14,13,12,23,22,21);
	if (bn_add_words(r_d, r_d, t_d, BN_NIST_384_TOP))
		++carry;
	/*S4*/
	nist_set_384(t_d,buf,19,18,17,16,15,14,13,12,20,0,23,0);
	if (bn_add_words(r_d, r_d, t_d, BN_NIST_384_TOP))
		++carry;
	/*S5*/
	nist_set_256(t_d, buf, 0, 0, 0, 0, 23-4, 22-4, 21-4, 20-4);
	if (bn_add_words(r_d+(128/BN_BITS2), r_d+(128/BN_BITS2), 
		t_d, BN_NIST_256_TOP))
		++carry;
	/*S6*/
	nist_set_384(t_d,buf,0,0,0,0,0,0,23,22,21,0,0,20);
	if (bn_add_words(r_d, r_d, t_d, BN_NIST_384_TOP))
		++carry;
	/*D1*/
	nist_set_384(t_d,buf,22,21,20,19,18,17,16,15,14,13,12,23);
	if (bn_sub_words(r_d, r_d, t_d, BN_NIST_384_TOP))
		--carry;
	/*D2*/
	nist_set_384(t_d,buf,0,0,0,0,0,0,0,23,22,21,20,0);
	if (bn_sub_words(r_d, r_d, t_d, BN_NIST_384_TOP))
		--carry;
	/*D3*/
	nist_set_384(t_d,buf,0,0,0,0,0,0,0,23,23,0,0,0);
	if (bn_sub_words(r_d, r_d, t_d, BN_NIST_384_TOP))
		--carry;
	
	if (carry)
		{
		if (carry > 0)
			bn_sub_words(r_d, r_d, _384_data + BN_NIST_384_TOP *
				--carry, BN_NIST_384_TOP);
		else
			{
			carry = -carry;
			bn_add_words(r_d, r_d, _384_data + BN_NIST_384_TOP *
				--carry, BN_NIST_384_TOP);
			}
		}

	r->top = BN_NIST_384_TOP;
	bn_correct_top(r);
	if (BN_ucmp(r, field) >= 0)
		{
		bn_sub_words(r_d, r_d, _nist_p_384, BN_NIST_384_TOP);
		bn_correct_top(r);
		}
	bn_check_top(r);
	return 1;
#else
	return 0;
#endif
	}

int BN_nist_mod_521(BIGNUM *r, const BIGNUM *a, const BIGNUM *field,
	BN_CTX *ctx)
	{
#if BN_BITS2 == 64
#define BN_NIST_521_TOP_MASK	(BN_ULONG)0x1FF
#elif BN_BITS2 == 32
#define BN_NIST_521_TOP_MASK	(BN_ULONG)0x1FF
#elif BN_BITS2 == 16
#define BN_NIST_521_TOP_MASK	(BN_ULONG)0x1FF
#elif BN_BITS2 == 8
#define BN_NIST_521_TOP_MASK	(BN_ULONG)0x1
#endif
	int	top, ret = 0;
	BN_ULONG *r_d;
	BIGNUM	*tmp;

	/* check whether a reduction is necessary */
	top = a->top;
	if (top < BN_NIST_521_TOP  || ( top == BN_NIST_521_TOP &&
           (!(a->d[BN_NIST_521_TOP-1] & ~(BN_NIST_521_TOP_MASK)))))
		return (r == a)? 1 : (BN_copy(r ,a) != NULL);

	BN_CTX_start(ctx);
	tmp = BN_CTX_get(ctx);
	if (!tmp)
		goto err;

	if (!bn_wexpand(tmp, BN_NIST_521_TOP))
		goto err;
	nist_cp_bn(tmp->d, a->d, BN_NIST_521_TOP);

	tmp->top = BN_NIST_521_TOP;
        tmp->d[BN_NIST_521_TOP-1]  &= BN_NIST_521_TOP_MASK;
	bn_correct_top(tmp);

	if (!BN_rshift(r, a, 521))
		goto err;

	if (!BN_uadd(r, tmp, r))
		goto err;
	top = r->top;
	r_d = r->d;
	if (top == BN_NIST_521_TOP  && 
           (r_d[BN_NIST_521_TOP-1] & ~(BN_NIST_521_TOP_MASK)))
		{
		BN_NIST_ADD_ONE(r_d)
		r_d[BN_NIST_521_TOP-1] &= BN_NIST_521_TOP_MASK; 
		}
	bn_correct_top(r);

	ret = 1;
err:
	BN_CTX_end(ctx);

	bn_check_top(r);
	return ret;
	}