text: /* crypto/ec/ec2_smpl.c */
  /* ====================================================================
   * Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED.
   *
   * The Elliptic Curve Public-Key Crypto Library (ECC Code) included
   * herein is developed by SUN MICROSYSTEMS, INC., and is contributed
   * to the OpenSSL project.
   *
   * The ECC Code is licensed pursuant to the OpenSSL open source
   * license provided below.
   *
   * The software is originally written by Sheueling Chang Shantz and
   * Douglas Stebila of Sun Microsystems Laboratories.
   *
   */
  /* ====================================================================
   * 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).
   *
   */
  
  #include <openssl/err.h>
  
  #include "internal/bn_int.h"
  #include "ec_lcl.h"
  
  #ifndef OPENSSL_NO_EC2M
  
  const EC_METHOD *EC_GF2m_simple_method(void)
  {
      static const EC_METHOD ret = {
          EC_FLAGS_DEFAULT_OCT,
          NID_X9_62_characteristic_two_field,
          ec_GF2m_simple_group_init,
          ec_GF2m_simple_group_finish,
          ec_GF2m_simple_group_clear_finish,
          ec_GF2m_simple_group_copy,
          ec_GF2m_simple_group_set_curve,
          ec_GF2m_simple_group_get_curve,
          ec_GF2m_simple_group_get_degree,
          ec_GF2m_simple_group_check_discriminant,
          ec_GF2m_simple_point_init,
          ec_GF2m_simple_point_finish,
          ec_GF2m_simple_point_clear_finish,
          ec_GF2m_simple_point_copy,
          ec_GF2m_simple_point_set_to_infinity,
          0 /* set_Jprojective_coordinates_GFp */ ,
          0 /* get_Jprojective_coordinates_GFp */ ,
          ec_GF2m_simple_point_set_affine_coordinates,
          ec_GF2m_simple_point_get_affine_coordinates,
          0, 0, 0,
          ec_GF2m_simple_add,
          ec_GF2m_simple_dbl,
          ec_GF2m_simple_invert,
          ec_GF2m_simple_is_at_infinity,
          ec_GF2m_simple_is_on_curve,
          ec_GF2m_simple_cmp,
          ec_GF2m_simple_make_affine,
          ec_GF2m_simple_points_make_affine,
  
          /*
           * the following three method functions are defined in ec2_mult.c
           */
          ec_GF2m_simple_mul,
          ec_GF2m_precompute_mult,
          ec_GF2m_have_precompute_mult,
  
          ec_GF2m_simple_field_mul,
          ec_GF2m_simple_field_sqr,
          ec_GF2m_simple_field_div,
          0 /* field_encode */ ,
          0 /* field_decode */ ,
          0                       /* field_set_to_one */
      };
  
      return &ret;
  }
  
  /*
   * Initialize a GF(2^m)-based EC_GROUP structure. Note that all other members
   * are handled by EC_GROUP_new.
   */
  int ec_GF2m_simple_group_init(EC_GROUP *group)
  {
      group->field = BN_new();
      group->a = BN_new();
      group->b = BN_new();
  
      if (group->field == NULL || group->a == NULL || group->b == NULL) {
          BN_free(group->field);
          BN_free(group->a);
          BN_free(group->b);
          return 0;
      }
      return 1;
  }
  
  /*
   * Free a GF(2^m)-based EC_GROUP structure. Note that all other members are
   * handled by EC_GROUP_free.
   */
  void ec_GF2m_simple_group_finish(EC_GROUP *group)
  {
      BN_free(group->field);
      BN_free(group->a);
      BN_free(group->b);
  }
  
  /*
   * Clear and free a GF(2^m)-based EC_GROUP structure. Note that all other
   * members are handled by EC_GROUP_clear_free.
   */
  void ec_GF2m_simple_group_clear_finish(EC_GROUP *group)
  {
      BN_clear_free(group->field);
      BN_clear_free(group->a);
      BN_clear_free(group->b);
      group->poly[0] = 0;
      group->poly[1] = 0;
      group->poly[2] = 0;
      group->poly[3] = 0;
      group->poly[4] = 0;
      group->poly[5] = -1;
  }
  
  /*
   * Copy a GF(2^m)-based EC_GROUP structure. Note that all other members are
   * handled by EC_GROUP_copy.
   */
  int ec_GF2m_simple_group_copy(EC_GROUP *dest, const EC_GROUP *src)
  {
      if (!BN_copy(dest->field, src->field))
          return 0;
      if (!BN_copy(dest->a, src->a))
          return 0;
      if (!BN_copy(dest->b, src->b))
          return 0;
      dest->poly[0] = src->poly[0];
      dest->poly[1] = src->poly[1];
      dest->poly[2] = src->poly[2];
      dest->poly[3] = src->poly[3];
      dest->poly[4] = src->poly[4];
      dest->poly[5] = src->poly[5];
      if (bn_wexpand(dest->a, (int)(dest->poly[0] + BN_BITS2 - 1) / BN_BITS2) ==
          NULL)
          return 0;
      if (bn_wexpand(dest->b, (int)(dest->poly[0] + BN_BITS2 - 1) / BN_BITS2) ==
          NULL)
          return 0;
      bn_set_all_zero(dest->a);
      bn_set_all_zero(dest->b);
      return 1;
  }
  
  /* Set the curve parameters of an EC_GROUP structure. */
  int ec_GF2m_simple_group_set_curve(EC_GROUP *group,
                                     const BIGNUM *p, const BIGNUM *a,
                                     const BIGNUM *b, BN_CTX *ctx)
  {
      int ret = 0, i;
  
      /* group->field */
      if (!BN_copy(group->field, p))
          goto err;
      i = BN_GF2m_poly2arr(group->field, group->poly, 6) - 1;
      if ((i != 5) && (i != 3)) {
          ECerr(EC_F_EC_GF2M_SIMPLE_GROUP_SET_CURVE, EC_R_UNSUPPORTED_FIELD);
          goto err;
      }
  
      /* group->a */
      if (!BN_GF2m_mod_arr(group->a, a, group->poly))
          goto err;
      if (bn_wexpand(group->a, (int)(group->poly[0] + BN_BITS2 - 1) / BN_BITS2)
          == NULL)
          goto err;
      bn_set_all_zero(group->a);
  
      /* group->b */
      if (!BN_GF2m_mod_arr(group->b, b, group->poly))
          goto err;
      if (bn_wexpand(group->b, (int)(group->poly[0] + BN_BITS2 - 1) / BN_BITS2)
          == NULL)
          goto err;
      bn_set_all_zero(group->b);
  
      ret = 1;
   err:
      return ret;
  }
  
  /*
   * Get the curve parameters of an EC_GROUP structure. If p, a, or b are NULL
   * then there values will not be set but the method will return with success.
   */
  int ec_GF2m_simple_group_get_curve(const EC_GROUP *group, BIGNUM *p,
                                     BIGNUM *a, BIGNUM *b, BN_CTX *ctx)
  {
      int ret = 0;
  
      if (p != NULL) {
          if (!BN_copy(p, group->field))
              return 0;
      }
  
      if (a != NULL) {
          if (!BN_copy(a, group->a))
              goto err;
      }
  
      if (b != NULL) {
          if (!BN_copy(b, group->b))
              goto err;
      }
  
      ret = 1;
  
   err:
      return ret;
  }
  
  /*
   * Gets the degree of the field.  For a curve over GF(2^m) this is the value
   * m.
   */
  int ec_GF2m_simple_group_get_degree(const EC_GROUP *group)
  {
      return BN_num_bits(group->field) - 1;
  }
  
  /*
   * Checks the discriminant of the curve. y^2 + x*y = x^3 + a*x^2 + b is an
   * elliptic curve <=> b != 0 (mod p)
   */
  int ec_GF2m_simple_group_check_discriminant(const EC_GROUP *group,
                                              BN_CTX *ctx)
  {
      int ret = 0;
      BIGNUM *b;
      BN_CTX *new_ctx = NULL;
  
      if (ctx == NULL) {
          ctx = new_ctx = BN_CTX_new();
          if (ctx == NULL) {
              ECerr(EC_F_EC_GF2M_SIMPLE_GROUP_CHECK_DISCRIMINANT,
                    ERR_R_MALLOC_FAILURE);
              goto err;
          }
      }
      BN_CTX_start(ctx);
      b = BN_CTX_get(ctx);
      if (b == NULL)
          goto err;
  
      if (!BN_GF2m_mod_arr(b, group->b, group->poly))
          goto err;
  
      /*
       * check the discriminant: y^2 + x*y = x^3 + a*x^2 + b is an elliptic
       * curve <=> b != 0 (mod p)
       */
      if (BN_is_zero(b))
          goto err;
  
      ret = 1;
  
   err:
      if (ctx != NULL)
          BN_CTX_end(ctx);
      BN_CTX_free(new_ctx);
      return ret;
  }
  
  /* Initializes an EC_POINT. */
  int ec_GF2m_simple_point_init(EC_POINT *point)
  {
      point->X = BN_new();
      point->Y = BN_new();
      point->Z = BN_new();
  
      if (point->X == NULL || point->Y == NULL || point->Z == NULL) {
          BN_free(point->X);
          BN_free(point->Y);
          BN_free(point->Z);
          return 0;
      }
      return 1;
  }
  
  /* Frees an EC_POINT. */
  void ec_GF2m_simple_point_finish(EC_POINT *point)
  {
      BN_free(point->X);
      BN_free(point->Y);
      BN_free(point->Z);
  }
  
  /* Clears and frees an EC_POINT. */
  void ec_GF2m_simple_point_clear_finish(EC_POINT *point)
  {
      BN_clear_free(point->X);
      BN_clear_free(point->Y);
      BN_clear_free(point->Z);
      point->Z_is_one = 0;
  }
  
  /*
   * Copy the contents of one EC_POINT into another.  Assumes dest is
   * initialized.
   */
  int ec_GF2m_simple_point_copy(EC_POINT *dest, const EC_POINT *src)
  {
      if (!BN_copy(dest->X, src->X))
          return 0;
      if (!BN_copy(dest->Y, src->Y))
          return 0;
      if (!BN_copy(dest->Z, src->Z))
          return 0;
      dest->Z_is_one = src->Z_is_one;
  
      return 1;
  }
  
  /*
   * Set an EC_POINT to the point at infinity. A point at infinity is
   * represented by having Z=0.
   */
  int ec_GF2m_simple_point_set_to_infinity(const EC_GROUP *group,
                                           EC_POINT *point)
  {
      point->Z_is_one = 0;
      BN_zero(point->Z);
      return 1;
  }
  
  /*
   * Set the coordinates of an EC_POINT using affine coordinates. Note that
   * the simple implementation only uses affine coordinates.
   */
  int ec_GF2m_simple_point_set_affine_coordinates(const EC_GROUP *group,
                                                  EC_POINT *point,
                                                  const BIGNUM *x,
                                                  const BIGNUM *y, BN_CTX *ctx)
  {
      int ret = 0;
      if (x == NULL || y == NULL) {
          ECerr(EC_F_EC_GF2M_SIMPLE_POINT_SET_AFFINE_COORDINATES,
                ERR_R_PASSED_NULL_PARAMETER);
          return 0;
      }
  
      if (!BN_copy(point->X, x))
          goto err;
      BN_set_negative(point->X, 0);
      if (!BN_copy(point->Y, y))
          goto err;
      BN_set_negative(point->Y, 0);
      if (!BN_copy(point->Z, BN_value_one()))
          goto err;
      BN_set_negative(point->Z, 0);
      point->Z_is_one = 1;
      ret = 1;
  
   err:
      return ret;
  }
  
  /*
   * Gets the affine coordinates of an EC_POINT. Note that the simple
   * implementation only uses affine coordinates.
   */
  int ec_GF2m_simple_point_get_affine_coordinates(const EC_GROUP *group,
                                                  const EC_POINT *point,
                                                  BIGNUM *x, BIGNUM *y,
                                                  BN_CTX *ctx)
  {
      int ret = 0;
  
      if (EC_POINT_is_at_infinity(group, point)) {
          ECerr(EC_F_EC_GF2M_SIMPLE_POINT_GET_AFFINE_COORDINATES,
                EC_R_POINT_AT_INFINITY);
          return 0;
      }
  
      if (BN_cmp(point->Z, BN_value_one())) {
          ECerr(EC_F_EC_GF2M_SIMPLE_POINT_GET_AFFINE_COORDINATES,
                ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);
          return 0;
      }
      if (x != NULL) {
          if (!BN_copy(x, point->X))
              goto err;
          BN_set_negative(x, 0);
      }
      if (y != NULL) {
          if (!BN_copy(y, point->Y))
              goto err;
          BN_set_negative(y, 0);
      }
      ret = 1;
  
   err:
      return ret;
  }
  
  /*
   * Computes a + b and stores the result in r.  r could be a or b, a could be
   * b. Uses algorithm A.10.2 of IEEE P1363.
   */
  int ec_GF2m_simple_add(const EC_GROUP *group, EC_POINT *r, const EC_POINT *a,
                         const EC_POINT *b, BN_CTX *ctx)
  {
      BN_CTX *new_ctx = NULL;
      BIGNUM *x0, *y0, *x1, *y1, *x2, *y2, *s, *t;
      int ret = 0;
  
      if (EC_POINT_is_at_infinity(group, a)) {
          if (!EC_POINT_copy(r, b))
              return 0;
          return 1;
      }
  
      if (EC_POINT_is_at_infinity(group, b)) {
          if (!EC_POINT_copy(r, a))
              return 0;
          return 1;
      }
  
      if (ctx == NULL) {
          ctx = new_ctx = BN_CTX_new();
          if (ctx == NULL)
              return 0;
      }
  
      BN_CTX_start(ctx);
      x0 = BN_CTX_get(ctx);
      y0 = BN_CTX_get(ctx);
      x1 = BN_CTX_get(ctx);
      y1 = BN_CTX_get(ctx);
      x2 = BN_CTX_get(ctx);
      y2 = BN_CTX_get(ctx);
      s = BN_CTX_get(ctx);
      t = BN_CTX_get(ctx);
      if (t == NULL)
          goto err;
  
      if (a->Z_is_one) {
          if (!BN_copy(x0, a->X))
              goto err;
          if (!BN_copy(y0, a->Y))
              goto err;
      } else {
          if (!EC_POINT_get_affine_coordinates_GF2m(group, a, x0, y0, ctx))
              goto err;
      }
      if (b->Z_is_one) {
          if (!BN_copy(x1, b->X))
              goto err;
          if (!BN_copy(y1, b->Y))
              goto err;
      } else {
          if (!EC_POINT_get_affine_coordinates_GF2m(group, b, x1, y1, ctx))
              goto err;
      }
  
      if (BN_GF2m_cmp(x0, x1)) {
          if (!BN_GF2m_add(t, x0, x1))
              goto err;
          if (!BN_GF2m_add(s, y0, y1))
              goto err;
          if (!group->meth->field_div(group, s, s, t, ctx))
              goto err;
          if (!group->meth->field_sqr(group, x2, s, ctx))
              goto err;
          if (!BN_GF2m_add(x2, x2, group->a))
              goto err;
          if (!BN_GF2m_add(x2, x2, s))
              goto err;
          if (!BN_GF2m_add(x2, x2, t))
              goto err;
      } else {
          if (BN_GF2m_cmp(y0, y1) || BN_is_zero(x1)) {
              if (!EC_POINT_set_to_infinity(group, r))
                  goto err;
              ret = 1;
              goto err;
          }
          if (!group->meth->field_div(group, s, y1, x1, ctx))
              goto err;
          if (!BN_GF2m_add(s, s, x1))
              goto err;
  
          if (!group->meth->field_sqr(group, x2, s, ctx))
              goto err;
          if (!BN_GF2m_add(x2, x2, s))
              goto err;
          if (!BN_GF2m_add(x2, x2, group->a))
              goto err;
      }
  
      if (!BN_GF2m_add(y2, x1, x2))
          goto err;
      if (!group->meth->field_mul(group, y2, y2, s, ctx))
          goto err;
      if (!BN_GF2m_add(y2, y2, x2))
          goto err;
      if (!BN_GF2m_add(y2, y2, y1))
          goto err;
  
      if (!EC_POINT_set_affine_coordinates_GF2m(group, r, x2, y2, ctx))
          goto err;
  
      ret = 1;
  
   err:
      BN_CTX_end(ctx);
      BN_CTX_free(new_ctx);
      return ret;
  }
  
  /*
   * Computes 2 * a and stores the result in r.  r could be a. Uses algorithm
   * A.10.2 of IEEE P1363.
   */
  int ec_GF2m_simple_dbl(const EC_GROUP *group, EC_POINT *r, const EC_POINT *a,
                         BN_CTX *ctx)
  {
      return ec_GF2m_simple_add(group, r, a, a, ctx);
  }
  
  int ec_GF2m_simple_invert(const EC_GROUP *group, EC_POINT *point, BN_CTX *ctx)
  {
      if (EC_POINT_is_at_infinity(group, point) || BN_is_zero(point->Y))
          /* point is its own inverse */
          return 1;
  
      if (!EC_POINT_make_affine(group, point, ctx))
          return 0;
      return BN_GF2m_add(point->Y, point->X, point->Y);
  }
  
  /* Indicates whether the given point is the point at infinity. */
  int ec_GF2m_simple_is_at_infinity(const EC_GROUP *group,
                                    const EC_POINT *point)
  {
      return BN_is_zero(point->Z);
  }
  
  /*-
   * Determines whether the given EC_POINT is an actual point on the curve defined
   * in the EC_GROUP.  A point is valid if it satisfies the Weierstrass equation:
   *      y^2 + x*y = x^3 + a*x^2 + b.
   */
  int ec_GF2m_simple_is_on_curve(const EC_GROUP *group, const EC_POINT *point,
                                 BN_CTX *ctx)
  {
      int ret = -1;
      BN_CTX *new_ctx = NULL;
      BIGNUM *lh, *y2;
      int (*field_mul) (const EC_GROUP *, BIGNUM *, const BIGNUM *,
                        const BIGNUM *, BN_CTX *);
      int (*field_sqr) (const EC_GROUP *, BIGNUM *, const BIGNUM *, BN_CTX *);
  
      if (EC_POINT_is_at_infinity(group, point))
          return 1;
  
      field_mul = group->meth->field_mul;
      field_sqr = group->meth->field_sqr;
  
      /* only support affine coordinates */
      if (!point->Z_is_one)
          return -1;
  
      if (ctx == NULL) {
          ctx = new_ctx = BN_CTX_new();
          if (ctx == NULL)
              return -1;
      }
  
      BN_CTX_start(ctx);
      y2 = BN_CTX_get(ctx);
      lh = BN_CTX_get(ctx);
      if (lh == NULL)
          goto err;
  
      /*-
       * We have a curve defined by a Weierstrass equation
       *      y^2 + x*y = x^3 + a*x^2 + b.
       *  <=> x^3 + a*x^2 + x*y + b + y^2 = 0
       *  <=> ((x + a) * x + y ) * x + b + y^2 = 0
       */
      if (!BN_GF2m_add(lh, point->X, group->a))
          goto err;
      if (!field_mul(group, lh, lh, point->X, ctx))
          goto err;
      if (!BN_GF2m_add(lh, lh, point->Y))
          goto err;
      if (!field_mul(group, lh, lh, point->X, ctx))
          goto err;
      if (!BN_GF2m_add(lh, lh, group->b))
          goto err;
      if (!field_sqr(group, y2, point->Y, ctx))
          goto err;
      if (!BN_GF2m_add(lh, lh, y2))
          goto err;
      ret = BN_is_zero(lh);
   err:
      if (ctx)
          BN_CTX_end(ctx);
      BN_CTX_free(new_ctx);
      return ret;
  }
  
  /*-
   * Indicates whether two points are equal.
   * Return values:
   *  -1   error
   *   0   equal (in affine coordinates)
   *   1   not equal
   */
  int ec_GF2m_simple_cmp(const EC_GROUP *group, const EC_POINT *a,
                         const EC_POINT *b, BN_CTX *ctx)
  {
      BIGNUM *aX, *aY, *bX, *bY;
      BN_CTX *new_ctx = NULL;
      int ret = -1;
  
      if (EC_POINT_is_at_infinity(group, a)) {
          return EC_POINT_is_at_infinity(group, b) ? 0 : 1;
      }
  
      if (EC_POINT_is_at_infinity(group, b))
          return 1;
  
      if (a->Z_is_one && b->Z_is_one) {
          return ((BN_cmp(a->X, b->X) == 0) && BN_cmp(a->Y, b->Y) == 0) ? 0 : 1;
      }
  
      if (ctx == NULL) {
          ctx = new_ctx = BN_CTX_new();
          if (ctx == NULL)
              return -1;
      }
  
      BN_CTX_start(ctx);
      aX = BN_CTX_get(ctx);
      aY = BN_CTX_get(ctx);
      bX = BN_CTX_get(ctx);
      bY = BN_CTX_get(ctx);
      if (bY == NULL)
          goto err;
  
      if (!EC_POINT_get_affine_coordinates_GF2m(group, a, aX, aY, ctx))
          goto err;
      if (!EC_POINT_get_affine_coordinates_GF2m(group, b, bX, bY, ctx))
          goto err;
      ret = ((BN_cmp(aX, bX) == 0) && BN_cmp(aY, bY) == 0) ? 0 : 1;
  
   err:
      if (ctx)
          BN_CTX_end(ctx);
      BN_CTX_free(new_ctx);
      return ret;
  }
  
  /* Forces the given EC_POINT to internally use affine coordinates. */
  int ec_GF2m_simple_make_affine(const EC_GROUP *group, EC_POINT *point,
                                 BN_CTX *ctx)
  {
      BN_CTX *new_ctx = NULL;
      BIGNUM *x, *y;
      int ret = 0;
  
      if (point->Z_is_one || EC_POINT_is_at_infinity(group, point))
          return 1;
  
      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 (!EC_POINT_get_affine_coordinates_GF2m(group, point, x, y, ctx))
          goto err;
      if (!BN_copy(point->X, x))
          goto err;
      if (!BN_copy(point->Y, y))
          goto err;
      if (!BN_one(point->Z))
          goto err;
  
      ret = 1;
  
   err:
      if (ctx)
          BN_CTX_end(ctx);
      BN_CTX_free(new_ctx);
      return ret;
  }
  
  /*
   * Forces each of the EC_POINTs in the given array to use affine coordinates.
   */
  int ec_GF2m_simple_points_make_affine(const EC_GROUP *group, size_t num,
                                        EC_POINT *points[], BN_CTX *ctx)
  {
      size_t i;
  
      for (i = 0; i < num; i++) {
          if (!group->meth->make_affine(group, points[i], ctx))
              return 0;
      }
  
      return 1;
  }
  
  /* Wrapper to simple binary polynomial field multiplication implementation. */
  int ec_GF2m_simple_field_mul(const EC_GROUP *group, BIGNUM *r,
                               const BIGNUM *a, const BIGNUM *b, BN_CTX *ctx)
  {
      return BN_GF2m_mod_mul_arr(r, a, b, group->poly, ctx);
  }
  
  /* Wrapper to simple binary polynomial field squaring implementation. */
  int ec_GF2m_simple_field_sqr(const EC_GROUP *group, BIGNUM *r,
                               const BIGNUM *a, BN_CTX *ctx)
  {
      return BN_GF2m_mod_sqr_arr(r, a, group->poly, ctx);
  }
  
  /* Wrapper to simple binary polynomial field division implementation. */
  int ec_GF2m_simple_field_div(const EC_GROUP *group, BIGNUM *r,
                               const BIGNUM *a, const BIGNUM *b, BN_CTX *ctx)
  {
      return BN_GF2m_mod_div(r, a, b, group->field, ctx);
  }
  
  #endif
  