crypto/fipsmodule/ec/oct.c - boringssl - Git at Google

 /* Originally written by Bodo Moeller for the OpenSSL project.
  * ====================================================================
  * Copyright (c) 1998-2005 The OpenSSL Project.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  *
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in
  *    the documentation and/or other materials provided with the
  *    distribution.
  *
  * 3. All advertising materials mentioning features or use of this
  *    software must display the following acknowledgment:
  *    "This product includes software developed by the OpenSSL Project
  *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
  *
  * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
  *    endorse or promote products derived from this software without
  *    prior written permission. For written permission, please contact
  *    openssl-core@openssl.org.
  *
  * 5. Products derived from this software may not be called "OpenSSL"
  *    nor may "OpenSSL" appear in their names without prior written
  *    permission of the OpenSSL Project.
  *
  * 6. Redistributions of any form whatsoever must retain the following
  *    acknowledgment:
  *    "This product includes software developed by the OpenSSL Project
  *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
  *
  * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
  * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
  * OF THE POSSIBILITY OF SUCH DAMAGE.
  * ====================================================================
  *
  * This product includes cryptographic software written by Eric Young
  * (eay@cryptsoft.com).  This product includes software written by Tim
  * Hudson (tjh@cryptsoft.com).
  *
  */
 /* ====================================================================
  * Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED.
  *
  * Portions of the attached software ("Contribution") are developed by
  * SUN MICROSYSTEMS, INC., and are contributed to the OpenSSL project.
  *
  * The Contribution is licensed pursuant to the OpenSSL open source
  * license provided above.
  *
  * The elliptic curve binary polynomial software is originally written by
  * Sheueling Chang Shantz and Douglas Stebila of Sun Microsystems
  * Laboratories. */

 #include <openssl/ec.h>

 #include <openssl/bn.h>
 #include <openssl/err.h>

 #include "internal.h"


 static size_t ec_GFp_simple_point2oct(const EC_GROUP *group,
                                       const EC_RAW_POINT *point,
                                       point_conversion_form_t form,
                                       uint8_t *buf, size_t len) {
   if (form != POINT_CONVERSION_COMPRESSED &&
       form != POINT_CONVERSION_UNCOMPRESSED) {
     OPENSSL_PUT_ERROR(EC, EC_R_INVALID_FORM);
     return 0;
   }

   if (ec_GFp_simple_is_at_infinity(group, point)) {
     OPENSSL_PUT_ERROR(EC, EC_R_POINT_AT_INFINITY);
     return 0;
   }

   const size_t field_len = BN_num_bytes(&group->field);
   size_t output_len = 1 /* type byte */ + field_len;
   if (form == POINT_CONVERSION_UNCOMPRESSED) {
     // Uncompressed points have a second coordinate.
     output_len += field_len;
   }

   // if 'buf' is NULL, just return required length
   if (buf != NULL) {
     if (len < output_len) {
       OPENSSL_PUT_ERROR(EC, EC_R_BUFFER_TOO_SMALL);
       return 0;
     }

     uint8_t y_buf[EC_MAX_BYTES];
     size_t field_len_out;
     if (!ec_point_get_affine_coordinate_bytes(
             group, buf + 1 /* x */,
             form == POINT_CONVERSION_COMPRESSED ? y_buf : buf + 1 + field_len,
             &field_len_out, field_len, point)) {
       return 0;
     }

     if (field_len_out != field_len) {
       OPENSSL_PUT_ERROR(EC, ERR_R_INTERNAL_ERROR);
       return 0;
     }

     if (form == POINT_CONVERSION_COMPRESSED) {
       buf[0] = form + (y_buf[field_len - 1] & 1);
     } else {
       buf[0] = form;
     }
   }

   return output_len;
 }

 static int ec_GFp_simple_oct2point(const EC_GROUP *group, EC_POINT *point,
                                    const uint8_t *buf, size_t len,
                                    BN_CTX *ctx) {
   BN_CTX *new_ctx = NULL;
   int ret = 0, used_ctx = 0;

   if (len == 0) {
     OPENSSL_PUT_ERROR(EC, EC_R_BUFFER_TOO_SMALL);
     goto err;
   }

   point_conversion_form_t form = buf[0];
   const int y_bit = form & 1;
   form = form & ~1U;
   if ((form != POINT_CONVERSION_COMPRESSED &&
        form != POINT_CONVERSION_UNCOMPRESSED) ||
       (form == POINT_CONVERSION_UNCOMPRESSED && y_bit)) {
     OPENSSL_PUT_ERROR(EC, EC_R_INVALID_ENCODING);
     goto err;
   }

   const size_t field_len = BN_num_bytes(&group->field);
   size_t enc_len = 1 /* type byte */ + field_len;
   if (form == POINT_CONVERSION_UNCOMPRESSED) {
     // Uncompressed points have a second coordinate.
     enc_len += field_len;
   }

   if (len != enc_len) {
     OPENSSL_PUT_ERROR(EC, EC_R_INVALID_ENCODING);
     goto err;
   }

   if (ctx == NULL) {
     ctx = new_ctx = BN_CTX_new();
     if (ctx == NULL) {
       goto err;
     }
   }

   BN_CTX_start(ctx);
   used_ctx = 1;
   BIGNUM *x = BN_CTX_get(ctx);
   BIGNUM *y = BN_CTX_get(ctx);
   if (x == NULL || y == NULL) {
     goto err;
   }

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

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

   ret = 1;

 err:
   if (used_ctx) {
     BN_CTX_end(ctx);
   }
   BN_CTX_free(new_ctx);
   return ret;
 }

 int EC_POINT_oct2point(const EC_GROUP *group, EC_POINT *point,
                        const uint8_t *buf, size_t len, BN_CTX *ctx) {
   if (EC_GROUP_cmp(group, point->group, NULL) != 0) {
     OPENSSL_PUT_ERROR(EC, EC_R_INCOMPATIBLE_OBJECTS);
     return 0;
   }
   return ec_GFp_simple_oct2point(group, point, buf, len, ctx);
 }

 size_t EC_POINT_point2oct(const EC_GROUP *group, const EC_POINT *point,
                           point_conversion_form_t form, uint8_t *buf,
                           size_t len, BN_CTX *ctx) {
   if (EC_GROUP_cmp(group, point->group, NULL) != 0) {
     OPENSSL_PUT_ERROR(EC, EC_R_INCOMPATIBLE_OBJECTS);
     return 0;
   }
   return ec_GFp_simple_point2oct(group, &point->raw, form, buf, len);
 }

 int EC_POINT_set_compressed_coordinates_GFp(const EC_GROUP *group,
                                             EC_POINT *point, const BIGNUM *x,
                                             int y_bit, BN_CTX *ctx) {
   if (EC_GROUP_cmp(group, point->group, NULL) != 0) {
     OPENSSL_PUT_ERROR(EC, EC_R_INCOMPATIBLE_OBJECTS);
     return 0;
   }

   if (BN_is_negative(x) || BN_cmp(x, &group->field) >= 0) {
     OPENSSL_PUT_ERROR(EC, EC_R_INVALID_COMPRESSED_POINT);
     return 0;
   }

   BN_CTX *new_ctx = NULL;
   int ret = 0;

   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);
   BIGNUM *tmp1 = BN_CTX_get(ctx);
   BIGNUM *tmp2 = BN_CTX_get(ctx);
   BIGNUM *a = BN_CTX_get(ctx);
   BIGNUM *b = BN_CTX_get(ctx);
   BIGNUM *y = BN_CTX_get(ctx);
   if (y == NULL ||
       !EC_GROUP_get_curve_GFp(group, NULL, a, b, ctx)) {
     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_mod_sqr(tmp2, x, &group->field, ctx) ||
       !BN_mod_mul(tmp1, tmp2, x, &group->field, ctx)) {
     goto err;
   }

   // tmp1 := tmp1 + a*x
   if (group->a_is_minus3) {
     if (!bn_mod_lshift1_consttime(tmp2, x, &group->field, ctx) ||
         !bn_mod_add_consttime(tmp2, tmp2, x, &group->field, ctx) ||
         !bn_mod_sub_consttime(tmp1, tmp1, tmp2, &group->field, ctx)) {
       goto err;
     }
   } else {
     if (!BN_mod_mul(tmp2, a, x, &group->field, ctx) ||
         !bn_mod_add_consttime(tmp1, tmp1, tmp2, &group->field, ctx)) {
       goto err;
     }
   }

   // tmp1 := tmp1 + b
   if (!bn_mod_add_consttime(tmp1, tmp1, b, &group->field, ctx)) {
     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();
       OPENSSL_PUT_ERROR(EC, EC_R_INVALID_COMPRESSED_POINT);
     } else {
       OPENSSL_PUT_ERROR(EC, ERR_R_BN_LIB);
     }
     goto err;
   }

   if (y_bit != BN_is_odd(y)) {
     if (BN_is_zero(y)) {
       OPENSSL_PUT_ERROR(EC, EC_R_INVALID_COMPRESSION_BIT);
       goto err;
     }
     if (!BN_usub(y, &group->field, y)) {
       goto err;
     }
   }
   if (y_bit != BN_is_odd(y)) {
     OPENSSL_PUT_ERROR(EC, 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);
   BN_CTX_free(new_ctx);
   return ret;
 }
	/* Originally written by Bodo Moeller for the OpenSSL project.
	* ====================================================================
	* Copyright (c) 1998-2005 The OpenSSL Project. All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions
	* are met:
	*
	* 1. Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer.
	*
	* 2. Redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in
	* the documentation and/or other materials provided with the
	* distribution.
	*
	* 3. All advertising materials mentioning features or use of this
	* software must display the following acknowledgment:
	* "This product includes software developed by the OpenSSL Project
	* for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
	*
	* 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
	* endorse or promote products derived from this software without
	* prior written permission. For written permission, please contact
	* openssl-core@openssl.org.
	*
	* 5. Products derived from this software may not be called "OpenSSL"
	* nor may "OpenSSL" appear in their names without prior written
	* permission of the OpenSSL Project.
	*
	* 6. Redistributions of any form whatsoever must retain the following
	* acknowledgment:
	* "This product includes software developed by the OpenSSL Project
	* for use in the OpenSSL Toolkit (http://www.openssl.org/)"
	*
	* THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
	* EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
	* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
	* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
	* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
	* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
	* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
	* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
	* OF THE POSSIBILITY OF SUCH DAMAGE.
	* ====================================================================
	*
	* This product includes cryptographic software written by Eric Young
	* (eay@cryptsoft.com). This product includes software written by Tim
	* Hudson (tjh@cryptsoft.com).
	*
	*/
	/* ====================================================================
	* Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED.
	*
	* Portions of the attached software ("Contribution") are developed by
	* SUN MICROSYSTEMS, INC., and are contributed to the OpenSSL project.
	*
	* The Contribution is licensed pursuant to the OpenSSL open source
	* license provided above.
	*
	* The elliptic curve binary polynomial software is originally written by
	* Sheueling Chang Shantz and Douglas Stebila of Sun Microsystems
	* Laboratories. */

	#include <openssl/ec.h>

	#include <openssl/bn.h>
	#include <openssl/err.h>

	#include "internal.h"


	static size_t ec_GFp_simple_point2oct(const EC_GROUP *group,
	const EC_RAW_POINT *point,
	point_conversion_form_t form,
	uint8_t *buf, size_t len) {
	if (form != POINT_CONVERSION_COMPRESSED &&
	form != POINT_CONVERSION_UNCOMPRESSED) {
	OPENSSL_PUT_ERROR(EC, EC_R_INVALID_FORM);
	return 0;
	}

	if (ec_GFp_simple_is_at_infinity(group, point)) {
	OPENSSL_PUT_ERROR(EC, EC_R_POINT_AT_INFINITY);
	return 0;
	}

	const size_t field_len = BN_num_bytes(&group->field);
	size_t output_len = 1 /* type byte */ + field_len;
	if (form == POINT_CONVERSION_UNCOMPRESSED) {
	// Uncompressed points have a second coordinate.
	output_len += field_len;
	}

	// if 'buf' is NULL, just return required length
	if (buf != NULL) {
	if (len < output_len) {
	OPENSSL_PUT_ERROR(EC, EC_R_BUFFER_TOO_SMALL);
	return 0;
	}

	uint8_t y_buf[EC_MAX_BYTES];
	size_t field_len_out;
	if (!ec_point_get_affine_coordinate_bytes(
	group, buf + 1 /* x */,
	form == POINT_CONVERSION_COMPRESSED ? y_buf : buf + 1 + field_len,
	&field_len_out, field_len, point)) {
	return 0;
	}

	if (field_len_out != field_len) {
	OPENSSL_PUT_ERROR(EC, ERR_R_INTERNAL_ERROR);
	return 0;
	}

	if (form == POINT_CONVERSION_COMPRESSED) {
	buf[0] = form + (y_buf[field_len - 1] & 1);
	} else {
	buf[0] = form;
	}
	}

	return output_len;
	}

	static int ec_GFp_simple_oct2point(const EC_GROUP group, EC_POINT point,
	const uint8_t *buf, size_t len,
	BN_CTX *ctx) {
	BN_CTX *new_ctx = NULL;
	int ret = 0, used_ctx = 0;

	if (len == 0) {
	OPENSSL_PUT_ERROR(EC, EC_R_BUFFER_TOO_SMALL);
	goto err;
	}

	point_conversion_form_t form = buf[0];
	const int y_bit = form & 1;
	form = form & ~1U;
	if ((form != POINT_CONVERSION_COMPRESSED &&
	form != POINT_CONVERSION_UNCOMPRESSED) \|\|
	(form == POINT_CONVERSION_UNCOMPRESSED && y_bit)) {
	OPENSSL_PUT_ERROR(EC, EC_R_INVALID_ENCODING);
	goto err;
	}

	const size_t field_len = BN_num_bytes(&group->field);
	size_t enc_len = 1 /* type byte */ + field_len;
	if (form == POINT_CONVERSION_UNCOMPRESSED) {
	// Uncompressed points have a second coordinate.
	enc_len += field_len;
	}

	if (len != enc_len) {
	OPENSSL_PUT_ERROR(EC, EC_R_INVALID_ENCODING);
	goto err;
	}

	if (ctx == NULL) {
	ctx = new_ctx = BN_CTX_new();
	if (ctx == NULL) {
	goto err;
	}
	}

	BN_CTX_start(ctx);
	used_ctx = 1;
	BIGNUM *x = BN_CTX_get(ctx);
	BIGNUM *y = BN_CTX_get(ctx);
	if (x == NULL \|\| y == NULL) {
	goto err;
	}

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

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

	ret = 1;

	err:
	if (used_ctx) {
	BN_CTX_end(ctx);
	}
	BN_CTX_free(new_ctx);
	return ret;
	}

	int EC_POINT_oct2point(const EC_GROUP group, EC_POINT point,
	const uint8_t buf, size_t len, BN_CTX ctx) {
	if (EC_GROUP_cmp(group, point->group, NULL) != 0) {
	OPENSSL_PUT_ERROR(EC, EC_R_INCOMPATIBLE_OBJECTS);
	return 0;
	}
	return ec_GFp_simple_oct2point(group, point, buf, len, ctx);
	}

	size_t EC_POINT_point2oct(const EC_GROUP group, const EC_POINT point,
	point_conversion_form_t form, uint8_t *buf,
	size_t len, BN_CTX *ctx) {
	if (EC_GROUP_cmp(group, point->group, NULL) != 0) {
	OPENSSL_PUT_ERROR(EC, EC_R_INCOMPATIBLE_OBJECTS);
	return 0;
	}
	return ec_GFp_simple_point2oct(group, &point->raw, form, buf, len);
	}

	int EC_POINT_set_compressed_coordinates_GFp(const EC_GROUP *group,
	EC_POINT point, const BIGNUM x,
	int y_bit, BN_CTX *ctx) {
	if (EC_GROUP_cmp(group, point->group, NULL) != 0) {
	OPENSSL_PUT_ERROR(EC, EC_R_INCOMPATIBLE_OBJECTS);
	return 0;
	}

	if (BN_is_negative(x) \|\| BN_cmp(x, &group->field) >= 0) {
	OPENSSL_PUT_ERROR(EC, EC_R_INVALID_COMPRESSED_POINT);
	return 0;
	}

	BN_CTX *new_ctx = NULL;
	int ret = 0;

	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);
	BIGNUM *tmp1 = BN_CTX_get(ctx);
	BIGNUM *tmp2 = BN_CTX_get(ctx);
	BIGNUM *a = BN_CTX_get(ctx);
	BIGNUM *b = BN_CTX_get(ctx);
	BIGNUM *y = BN_CTX_get(ctx);
	if (y == NULL \|\|
	!EC_GROUP_get_curve_GFp(group, NULL, a, b, ctx)) {
	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_mod_sqr(tmp2, x, &group->field, ctx) \|\|
	!BN_mod_mul(tmp1, tmp2, x, &group->field, ctx)) {
	goto err;
	}

	// tmp1 := tmp1 + a*x
	if (group->a_is_minus3) {
	if (!bn_mod_lshift1_consttime(tmp2, x, &group->field, ctx) \|\|
	!bn_mod_add_consttime(tmp2, tmp2, x, &group->field, ctx) \|\|
	!bn_mod_sub_consttime(tmp1, tmp1, tmp2, &group->field, ctx)) {
	goto err;
	}
	} else {
	if (!BN_mod_mul(tmp2, a, x, &group->field, ctx) \|\|
	!bn_mod_add_consttime(tmp1, tmp1, tmp2, &group->field, ctx)) {
	goto err;
	}
	}

	// tmp1 := tmp1 + b
	if (!bn_mod_add_consttime(tmp1, tmp1, b, &group->field, ctx)) {
	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();
	OPENSSL_PUT_ERROR(EC, EC_R_INVALID_COMPRESSED_POINT);
	} else {
	OPENSSL_PUT_ERROR(EC, ERR_R_BN_LIB);
	}
	goto err;
	}

	if (y_bit != BN_is_odd(y)) {
	if (BN_is_zero(y)) {
	OPENSSL_PUT_ERROR(EC, EC_R_INVALID_COMPRESSION_BIT);
	goto err;
	}
	if (!BN_usub(y, &group->field, y)) {
	goto err;
	}
	}
	if (y_bit != BN_is_odd(y)) {
	OPENSSL_PUT_ERROR(EC, 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);
	BN_CTX_free(new_ctx);
	return ret;
	}