ecp_smpl.c

OpenSSL 0.9.8k 最新版OpenSSL

		else
			{
			if (x != NULL)
				{
				if (!BN_copy(x, &point->X)) goto err;
				}
			if (y != NULL)
				{
				if (!BN_copy(y, &point->Y)) goto err;
				}
			}
		}
	else
		{
		if (!BN_mod_inverse(Z_1, Z_, &group->field, ctx))
			{
			ECerr(EC_F_EC_GFP_SIMPLE_POINT_GET_AFFINE_COORDINATES, ERR_R_BN_LIB);
			goto err;
			}
		
		if (group->meth->field_encode == 0)
			{
			/* field_sqr works on standard representation */
			if (!group->meth->field_sqr(group, Z_2, Z_1, ctx)) goto err;
			}
		else
			{
			if (!BN_mod_sqr(Z_2, Z_1, &group->field, ctx)) goto err;
			}
	
		if (x != NULL)
			{
			/* in the Montgomery case, field_mul will cancel out Montgomery factor in X: */
			if (!group->meth->field_mul(group, x, &point->X, Z_2, ctx)) goto err;
			}

		if (y != NULL)
			{
			if (group->meth->field_encode == 0)
				{
				/* field_mul works on standard representation */
				if (!group->meth->field_mul(group, Z_3, Z_2, Z_1, ctx)) goto err;
				}
			else
				{
				if (!BN_mod_mul(Z_3, Z_2, Z_1, &group->field, ctx)) goto err;
				}

			/* in the Montgomery case, field_mul will cancel out Montgomery factor in Y: */
			if (!group->meth->field_mul(group, y, &point->Y, Z_3, ctx)) goto err;
			}
		}

	ret = 1;

 err:
	BN_CTX_end(ctx);
	if (new_ctx != NULL)
		BN_CTX_free(new_ctx);
	return ret;
	}


int ec_GFp_simple_set_compressed_coordinates(const EC_GROUP *group, EC_POINT *point,
	const BIGNUM *x_, int y_bit, BN_CTX *ctx)
	{
	BN_CTX *new_ctx = NULL;
	BIGNUM *tmp1, *tmp2, *x, *y;
	int ret = 0;

	/* clear error queue*/
	ERR_clear_error();

	if (ctx == NULL)
		{
		ctx = new_ctx = BN_CTX_new();
		if (ctx == NULL)
			return 0;
		}

	y_bit = (y_bit != 0);

	BN_CTX_start(ctx);
	tmp1 = BN_CTX_get(ctx);
	tmp2 = BN_CTX_get(ctx);
	x = BN_CTX_get(ctx);
	y = BN_CTX_get(ctx);
	if (y == NULL) goto err;

	/* Recover y.  We have a Weierstrass equation
	 *     y^2 = x^3 + a*x + b,
	 * so  y  is one of the square roots of  x^3 + a*x + b.
	 */

	/* tmp1 := x^3 */
	if (!BN_nnmod(x, x_, &group->field,ctx)) goto err;
	if (group->meth->field_decode == 0)
		{
		/* field_{sqr,mul} work on standard representation */
		if (!group->meth->field_sqr(group, tmp2, x_, ctx)) goto err;
		if (!group->meth->field_mul(group, tmp1, tmp2, x_, ctx)) goto err;
		}
	else
		{
		if (!BN_mod_sqr(tmp2, x_, &group->field, ctx)) goto err;
		if (!BN_mod_mul(tmp1, tmp2, x_, &group->field, ctx)) goto err;
		}
	
	/* tmp1 := tmp1 + a*x */
	if (group->a_is_minus3)
		{
		if (!BN_mod_lshift1_quick(tmp2, x, &group->field)) goto err;
		if (!BN_mod_add_quick(tmp2, tmp2, x, &group->field)) goto err;
		if (!BN_mod_sub_quick(tmp1, tmp1, tmp2, &group->field)) goto err;
		}
	else
		{
		if (group->meth->field_decode)
			{
			if (!group->meth->field_decode(group, tmp2, &group->a, ctx)) goto err;
			if (!BN_mod_mul(tmp2, tmp2, x, &group->field, ctx)) goto err;
			}
		else
			{
			/* field_mul works on standard representation */
			if (!group->meth->field_mul(group, tmp2, &group->a, x, ctx)) goto err;
			}
		
		if (!BN_mod_add_quick(tmp1, tmp1, tmp2, &group->field)) goto err;
		}
	
	/* tmp1 := tmp1 + b */
	if (group->meth->field_decode)
		{
		if (!group->meth->field_decode(group, tmp2, &group->b, ctx)) goto err;
		if (!BN_mod_add_quick(tmp1, tmp1, tmp2, &group->field)) goto err;
		}
	else
		{
		if (!BN_mod_add_quick(tmp1, tmp1, &group->b, &group->field)) goto err;
		}
	
	if (!BN_mod_sqrt(y, tmp1, &group->field, ctx))
		{
		unsigned long err = ERR_peek_last_error();
		
		if (ERR_GET_LIB(err) == ERR_LIB_BN && ERR_GET_REASON(err) == BN_R_NOT_A_SQUARE)
			{
			ERR_clear_error();
			ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES, EC_R_INVALID_COMPRESSED_POINT);
			}
		else
			ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES, ERR_R_BN_LIB);
		goto err;
		}

	if (y_bit != BN_is_odd(y))
		{
		if (BN_is_zero(y))
			{
			int kron;

			kron = BN_kronecker(x, &group->field, ctx);
			if (kron == -2) goto err;

			if (kron == 1)
				ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES, EC_R_INVALID_COMPRESSION_BIT);
			else
				/* BN_mod_sqrt() should have cought this error (not a square) */
				ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES, EC_R_INVALID_COMPRESSED_POINT);
			goto err;
			}
		if (!BN_usub(y, &group->field, y)) goto err;
		}
	if (y_bit != BN_is_odd(y))
		{
		ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES, ERR_R_INTERNAL_ERROR);
		goto err;
		}

	if (!EC_POINT_set_affine_coordinates_GFp(group, point, x, y, ctx)) goto err;

	ret = 1;

 err:
	BN_CTX_end(ctx);
	if (new_ctx != NULL)
		BN_CTX_free(new_ctx);
	return ret;
	}


size_t ec_GFp_simple_point2oct(const EC_GROUP *group, const EC_POINT *point, point_conversion_form_t form,
	unsigned char *buf, size_t len, BN_CTX *ctx)
	{
	size_t ret;
	BN_CTX *new_ctx = NULL;
	int used_ctx = 0;
	BIGNUM *x, *y;
	size_t field_len, i, skip;

	if ((form != POINT_CONVERSION_COMPRESSED)
		&& (form != POINT_CONVERSION_UNCOMPRESSED)
		&& (form != POINT_CONVERSION_HYBRID))
		{
		ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT, EC_R_INVALID_FORM);
		goto err;
		}

	if (EC_POINT_is_at_infinity(group, point))
		{
		/* encodes to a single 0 octet */
		if (buf != NULL)
			{
			if (len < 1)
				{
				ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT, EC_R_BUFFER_TOO_SMALL);
				return 0;
				}
			buf[0] = 0;
			}
		return 1;
		}


	/* ret := required output buffer length */
	field_len = BN_num_bytes(&group->field);
	ret = (form == POINT_CONVERSION_COMPRESSED) ? 1 + field_len : 1 + 2*field_len;

	/* if 'buf' is NULL, just return required length */
	if (buf != NULL)
		{
		if (len < ret)
			{
			ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT, EC_R_BUFFER_TOO_SMALL);
			goto err;
			}

		if (ctx == NULL)
			{
			ctx = new_ctx = BN_CTX_new();
			if (ctx == NULL)
				return 0;
			}

		BN_CTX_start(ctx);
		used_ctx = 1;
		x = BN_CTX_get(ctx);
		y = BN_CTX_get(ctx);
		if (y == NULL) goto err;

		if (!EC_POINT_get_affine_coordinates_GFp(group, point, x, y, ctx)) goto err;

		if ((form == POINT_CONVERSION_COMPRESSED || form == POINT_CONVERSION_HYBRID) && BN_is_odd(y))
			buf[0] = form + 1;
		else
			buf[0] = form;
	
		i = 1;
		
		skip = field_len - BN_num_bytes(x);
		if (skip > field_len)
			{
			ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR);
			goto err;
			}
		while (skip > 0)
			{
			buf[i++] = 0;
			skip--;
			}
		skip = BN_bn2bin(x, buf + i);
		i += skip;
		if (i != 1 + field_len)
			{
			ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR);
			goto err;
			}

		if (form == POINT_CONVERSION_UNCOMPRESSED || form == POINT_CONVERSION_HYBRID)
			{
			skip = field_len - BN_num_bytes(y);
			if (skip > field_len)
				{
				ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR);
				goto err;
				}
			while (skip > 0)
				{
				buf[i++] = 0;
				skip--;
				}
			skip = BN_bn2bin(y, buf + i);
			i += skip;
			}

		if (i != ret)
			{
			ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR);
			goto err;
			}
		}
	
	if (used_ctx)
		BN_CTX_end(ctx);
	if (new_ctx != NULL)
		BN_CTX_free(new_ctx);
	return ret;

 err:
	if (used_ctx)
		BN_CTX_end(ctx);
	if (new_ctx != NULL)
		BN_CTX_free(new_ctx);
	return 0;
	}


int ec_GFp_simple_oct2point(const EC_GROUP *group, EC_POINT *point,
	const unsigned char *buf, size_t len, BN_CTX *ctx)
	{
	point_conversion_form_t form;
	int y_bit;
	BN_CTX *new_ctx = NULL;
	BIGNUM *x, *y;
	size_t field_len, enc_len;
	int ret = 0;

	if (len == 0)
		{
		ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_BUFFER_TOO_SMALL);
		return 0;
		}
	form = buf[0];
	y_bit = form & 1;
	form = form & ~1U;
	if ((form != 0)	&& (form != POINT_CONVERSION_COMPRESSED)
		&& (form != POINT_CONVERSION_UNCOMPRESSED)
		&& (form != POINT_CONVERSION_HYBRID))
		{
		ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
		return 0;
		}
	if ((form == 0 || form == POINT_CONVERSION_UNCOMPRESSED) && y_bit)
		{
		ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
		return 0;
		}

	if (form == 0)
		{
		if (len != 1)
			{
			ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
			return 0;
			}

		return EC_POINT_set_to_infinity(group, point);
		}
	
	field_len = BN_num_bytes(&group->field);
	enc_len = (form == POINT_CONVERSION_COMPRESSED) ? 1 + field_len : 1 + 2*field_len;

	if (len != enc_len)
		{
		ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
		return 0;
		}

	if (ctx == NULL)
		{
		ctx = new_ctx = BN_CTX_new();
		if (ctx == NULL)
			return 0;
		}

	BN_CTX_start(ctx);
	x = BN_CTX_get(ctx);
	y = BN_CTX_get(ctx);
	if (y == NULL) goto err;

	if (!BN_bin2bn(buf + 1, field_len, x)) goto err;
	if (BN_ucmp(x, &group->field) >= 0)
		{
		ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
		goto err;
		}

	if (form == POINT_CONVERSION_COMPRESSED)
		{
		if (!EC_POINT_set_compressed_coordinates_GFp(group, point, x, y_bit, ctx)) goto err;
		}
	else
		{
		if (!BN_bin2bn(buf + 1 + field_len, field_len, y)) goto err;
		if (BN_ucmp(y, &group->field) >= 0)
			{
			ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
			goto err;
			}
		if (form == POINT_CONVERSION_HYBRID)
			{
			if (y_bit != BN_is_odd(y))
				{
				ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING);
				goto err;
				}
			}

		if (!EC_POINT_set_affine_coordinates_GFp(group, point, x, y, ctx)) goto err;
		}
	
	if (!EC_POINT_is_on_curve(group, point, ctx)) /* test required by X9.62 */
		{
		ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_POINT_IS_NOT_ON_CURVE);
		goto err;
		}

	ret = 1;
	
 err:
	BN_CTX_end(ctx);
	if (new_ctx != NULL)
		BN_CTX_free(new_ctx);
	return ret;
	}


int ec_GFp_simple_add(const EC_GROUP *group, EC_POINT *r, const EC_POINT *a, const EC_POINT *b, BN_CTX *ctx)
	{
	int (*field_mul)(const EC_GROUP *, BIGNUM *, const BIGNUM *, const BIGNUM *, BN_CTX *);
	int (*field_sqr)(const EC_GROUP *, BIGNUM *, const BIGNUM *, BN_CTX *);
	const BIGNUM *p;
	BN_CTX *new_ctx = NULL;
	BIGNUM *n0, *n1, *n2, *n3, *n4, *n5, *n6;
	int ret = 0;
	
	if (a == b)
		return EC_POINT_dbl(group, r, a, ctx);
	if (EC_POINT_is_at_infinity(group, a))
		return EC_POINT_copy(r, b);
	if (EC_POINT_is_at_infinity(group, b))
		return EC_POINT_copy(r, a);
	
	field_mul = group->meth->field_mul;
	field_sqr = group->meth->field_sqr;
	p = &group->field;

	if (ctx == NULL)
		{
		ctx = new_ctx = BN_CTX_new();
		if (ctx == NULL)
			return 0;
		}

	BN_CTX_start(ctx);
	n0 = BN_CTX_get(ctx);
	n1 = BN_CTX_get(ctx);
	n2 = BN_CTX_get(ctx);
	n3 = BN_CTX_get(ctx);
	n4 = BN_CTX_get(ctx);
	n5 = BN_CTX_get(ctx);
	n6 = BN_CTX_get(ctx);
	if (n6 == NULL) goto end;

	/* Note that in this function we must not read components of 'a' or 'b'
	 * once we have written the corresponding components of 'r'.
	 * ('r' might be one of 'a' or 'b'.)
	 */

	/* n1, n2 */
	if (b->Z_is_one)
		{
		if (!BN_copy(n1, &a->X)) goto end;
		if (!BN_copy(n2, &a->Y)) goto end;
		/* n1 = X_a */
		/* n2 = Y_a */
		}
	else
		{
		if (!field_sqr(group, n0, &b->Z, ctx)) goto end;
		if (!field_mul(group, n1, &a->X, n0, ctx)) goto end;
		/* n1 = X_a * Z_b^2 */

		if (!field_mul(group, n0, n0, &b->Z, ctx)) goto end;
		if (!field_mul(group, n2, &a->Y, n0, ctx)) goto end;
		/* n2 = Y_a * Z_b^3 */
		}

	/* n3, n4 */
	if (a->Z_is_one)
		{
		if (!BN_copy(n3, &b->X)) goto end;
		if (!BN_copy(n4, &b->Y)) goto end;
		/* n3 = X_b */
		/* n4 = Y_b */
		}
	else
		{
		if (!field_sqr(group, n0, &a->Z, ctx)) goto end;
		if (!field_mul(group, n3, &b->X, n0, ctx)) goto end;
		/* n3 = X_b * Z_a^2 */

		if (!field_mul(group, n0, n0, &a->Z, ctx)) goto end;
		if (!field_mul(group, n4, &b->Y, n0, ctx)) goto end;
		/* n4 = Y_b * Z_a^3 */
		}

	/* n5, n6 */
	if (!BN_mod_sub_quick(n5, n1, n3, p)) goto end;
	if (!BN_mod_sub_quick(n6, n2, n4, p)) goto end;
	/* n5 = n1 - n3 */
	/* n6 = n2 - n4 */

	if (BN_is_zero(n5))
		{
		if (BN_is_zero(n6))
			{
			/* a is the same point as b */
			BN_CTX_end(ctx);
			ret = EC_POINT_dbl(group, r, a, ctx);
			ctx = NULL;
			goto end;
			}
		else
			{
			/* a is the inverse of b */
			BN_zero(&r->Z);
			r->Z_is_one = 0;
			ret = 1;
			goto end;
			}
		}

	/* 'n7', 'n8' */
	if (!BN_mod_add_quick(n1, n1, n3, p)) goto end;
	if (!BN_mod_add_quick(n2, n2, n4, p)) goto end;
	/* 'n7' = n1 + n3 */
	/* 'n8' = n2 + n4 */

	/* Z_r */
	if (a->Z_is_one && b->Z_is_one)
		{
		if (!BN_copy(&r->Z, n5)) goto end;
		}
	else
		{
		if (a->Z_is_one)
			{ if (!BN_copy(n0, &b->Z)) goto end; }
		else if (b->Z_is_one)
			{ if (!BN_copy(n0, &a->Z)) goto end; }
		else
			{ if (!field_mul(group, n0, &a->Z, &b->Z, ctx)) goto end; }
		if (!field_mul(group, &r->Z, n0, n5, ctx)) goto end;
		}
	r->Z_is_one = 0;
	/* Z_r = Z_a * Z_b * n5 */

	/* X_r */
	if (!field_sqr(group, n0, n6, ctx)) goto end;
	if (!field_sqr(group, n4, n5, ctx)) goto end;
	if (!field_mul(group, n3, n1, n4, ctx)) goto end;
	if (!BN_mod_sub_quick(&r->X, n0, n3, p)) goto end;
	/* X_r = n6^2 - n5^2 * 'n7' */
	
	/* 'n9' */
	if (!BN_mod_lshift1_quick(n0, &r->X, p)) goto end;
	if (!BN_mod_sub_quick(n0, n3, n0, p)) goto end;
	/* n9 = n5^2 * 'n7' - 2 * X_r */

	/* Y_r */
	if (!field_mul(group, n0, n0, n6, ctx)) goto end;
	if (!field_mul(group, n5, n4, n5, ctx)) goto end; /* now n5 is n5^3 */