text: /*
   * Copyright 2001-2018 The OpenSSL Project Authors. All Rights Reserved.
   * Copyright (c) 2002, Oracle and/or its affiliates. All rights reserved
   *
   * Licensed under the Apache License 2.0 (the "License").  You may not use
   * this file except in compliance with the License.  You can obtain a copy
   * in the file LICENSE in the source distribution or at
   * https://www.openssl.org/source/license.html
   */
  
  /*
   * ECDSA low level APIs are deprecated for public use, but still ok for
   * internal use.
   */
  #include "internal/deprecated.h"
  
  #include <openssl/err.h>
  
  #include "ec_local.h"
  
  const EC_METHOD *EC_GFp_mont_method(void)
  {
      static const EC_METHOD ret = {
          EC_FLAGS_DEFAULT_OCT,
          NID_X9_62_prime_field,
          ec_GFp_mont_group_init,
          ec_GFp_mont_group_finish,
          ec_GFp_mont_group_clear_finish,
          ec_GFp_mont_group_copy,
          ec_GFp_mont_group_set_curve,
          ec_GFp_simple_group_get_curve,
          ec_GFp_simple_group_get_degree,
          ec_group_simple_order_bits,
          ec_GFp_simple_group_check_discriminant,
          ec_GFp_simple_point_init,
          ec_GFp_simple_point_finish,
          ec_GFp_simple_point_clear_finish,
          ec_GFp_simple_point_copy,
          ec_GFp_simple_point_set_to_infinity,
          ec_GFp_simple_set_Jprojective_coordinates_GFp,
          ec_GFp_simple_get_Jprojective_coordinates_GFp,
          ec_GFp_simple_point_set_affine_coordinates,
          ec_GFp_simple_point_get_affine_coordinates,
          0, 0, 0,
          ec_GFp_simple_add,
          ec_GFp_simple_dbl,
          ec_GFp_simple_invert,
          ec_GFp_simple_is_at_infinity,
          ec_GFp_simple_is_on_curve,
          ec_GFp_simple_cmp,
          ec_GFp_simple_make_affine,
          ec_GFp_simple_points_make_affine,
          0 /* mul */ ,
          0 /* precompute_mult */ ,
          0 /* have_precompute_mult */ ,
          ec_GFp_mont_field_mul,
          ec_GFp_mont_field_sqr,
          0 /* field_div */ ,
          ec_GFp_mont_field_inv,
          ec_GFp_mont_field_encode,
          ec_GFp_mont_field_decode,
          ec_GFp_mont_field_set_to_one,
          ec_key_simple_priv2oct,
          ec_key_simple_oct2priv,
          0, /* set private */
          ec_key_simple_generate_key,
          ec_key_simple_check_key,
          ec_key_simple_generate_public_key,
          0, /* keycopy */
          0, /* keyfinish */
          ecdh_simple_compute_key,
          ecdsa_simple_sign_setup,
          ecdsa_simple_sign_sig,
          ecdsa_simple_verify_sig,
          0, /* field_inverse_mod_ord */
          ec_GFp_simple_blind_coordinates,
          ec_GFp_simple_ladder_pre,
          ec_GFp_simple_ladder_step,
          ec_GFp_simple_ladder_post
      };
  
      return &ret;
  }
  
  int ec_GFp_mont_group_init(EC_GROUP *group)
  {
      int ok;
  
      ok = ec_GFp_simple_group_init(group);
      group->field_data1 = NULL;
      group->field_data2 = NULL;
      return ok;
  }
  
  void ec_GFp_mont_group_finish(EC_GROUP *group)
  {
      BN_MONT_CTX_free(group->field_data1);
      group->field_data1 = NULL;
      BN_free(group->field_data2);
      group->field_data2 = NULL;
      ec_GFp_simple_group_finish(group);
  }
  
  void ec_GFp_mont_group_clear_finish(EC_GROUP *group)
  {
      BN_MONT_CTX_free(group->field_data1);
      group->field_data1 = NULL;
      BN_clear_free(group->field_data2);
      group->field_data2 = NULL;
      ec_GFp_simple_group_clear_finish(group);
  }
  
  int ec_GFp_mont_group_copy(EC_GROUP *dest, const EC_GROUP *src)
  {
      BN_MONT_CTX_free(dest->field_data1);
      dest->field_data1 = NULL;
      BN_clear_free(dest->field_data2);
      dest->field_data2 = NULL;
  
      if (!ec_GFp_simple_group_copy(dest, src))
          return 0;
  
      if (src->field_data1 != NULL) {
          dest->field_data1 = BN_MONT_CTX_new();
          if (dest->field_data1 == NULL)
              return 0;
          if (!BN_MONT_CTX_copy(dest->field_data1, src->field_data1))
              goto err;
      }
      if (src->field_data2 != NULL) {
          dest->field_data2 = BN_dup(src->field_data2);
          if (dest->field_data2 == NULL)
              goto err;
      }
  
      return 1;
  
   err:
      BN_MONT_CTX_free(dest->field_data1);
      dest->field_data1 = NULL;
      return 0;
  }
  
  int ec_GFp_mont_group_set_curve(EC_GROUP *group, const BIGNUM *p,
                                  const BIGNUM *a, const BIGNUM *b, BN_CTX *ctx)
  {
      BN_CTX *new_ctx = NULL;
      BN_MONT_CTX *mont = NULL;
      BIGNUM *one = NULL;
      int ret = 0;
  
      BN_MONT_CTX_free(group->field_data1);
      group->field_data1 = NULL;
      BN_free(group->field_data2);
      group->field_data2 = NULL;
  
      if (ctx == NULL) {
          ctx = new_ctx = BN_CTX_new_ex(group->libctx);
          if (ctx == NULL)
              return 0;
      }
  
      mont = BN_MONT_CTX_new();
      if (mont == NULL)
          goto err;
      if (!BN_MONT_CTX_set(mont, p, ctx)) {
          ECerr(EC_F_EC_GFP_MONT_GROUP_SET_CURVE, ERR_R_BN_LIB);
          goto err;
      }
      one = BN_new();
      if (one == NULL)
          goto err;
      if (!BN_to_montgomery(one, BN_value_one(), mont, ctx))
          goto err;
  
      group->field_data1 = mont;
      mont = NULL;
      group->field_data2 = one;
      one = NULL;
  
      ret = ec_GFp_simple_group_set_curve(group, p, a, b, ctx);
  
      if (!ret) {
          BN_MONT_CTX_free(group->field_data1);
          group->field_data1 = NULL;
          BN_free(group->field_data2);
          group->field_data2 = NULL;
      }
  
   err:
      BN_free(one);
      BN_CTX_free(new_ctx);
      BN_MONT_CTX_free(mont);
      return ret;
  }
  
  int ec_GFp_mont_field_mul(const EC_GROUP *group, BIGNUM *r, const BIGNUM *a,
                            const BIGNUM *b, BN_CTX *ctx)
  {
      if (group->field_data1 == NULL) {
          ECerr(EC_F_EC_GFP_MONT_FIELD_MUL, EC_R_NOT_INITIALIZED);
          return 0;
      }
  
      return BN_mod_mul_montgomery(r, a, b, group->field_data1, ctx);
  }
  
  int ec_GFp_mont_field_sqr(const EC_GROUP *group, BIGNUM *r, const BIGNUM *a,
                            BN_CTX *ctx)
  {
      if (group->field_data1 == NULL) {
          ECerr(EC_F_EC_GFP_MONT_FIELD_SQR, EC_R_NOT_INITIALIZED);
          return 0;
      }
  
      return BN_mod_mul_montgomery(r, a, a, group->field_data1, ctx);
  }
  
  /*-
   * Computes the multiplicative inverse of a in GF(p), storing the result in r.
   * If a is zero (or equivalent), you'll get a EC_R_CANNOT_INVERT error.
   * We have a Mont structure, so SCA hardening is FLT inversion.
   */
  int ec_GFp_mont_field_inv(const EC_GROUP *group, BIGNUM *r, const BIGNUM *a,
                              BN_CTX *ctx)
  {
      BIGNUM *e = NULL;
      BN_CTX *new_ctx = NULL;
      int ret = 0;
  
      if (group->field_data1 == NULL)
          return 0;
  
      if (ctx == NULL
              && (ctx = new_ctx = BN_CTX_secure_new_ex(group->libctx)) == NULL)
          return 0;
  
      BN_CTX_start(ctx);
      if ((e = BN_CTX_get(ctx)) == NULL)
          goto err;
  
      /* Inverse in constant time with Fermats Little Theorem */
      if (!BN_set_word(e, 2))
          goto err;
      if (!BN_sub(e, group->field, e))
          goto err;
      /*-
       * Exponent e is public.
       * No need for scatter-gather or BN_FLG_CONSTTIME.
       */
      if (!BN_mod_exp_mont(r, a, e, group->field, ctx, group->field_data1))
          goto err;
  
      /* throw an error on zero */
      if (BN_is_zero(r)) {
          ECerr(EC_F_EC_GFP_MONT_FIELD_INV, EC_R_CANNOT_INVERT);
          goto err;
      }
  
      ret = 1;
  
    err:
      BN_CTX_end(ctx);
      BN_CTX_free(new_ctx);
      return ret;
  }
  
  int ec_GFp_mont_field_encode(const EC_GROUP *group, BIGNUM *r,
                               const BIGNUM *a, BN_CTX *ctx)
  {
      if (group->field_data1 == NULL) {
          ECerr(EC_F_EC_GFP_MONT_FIELD_ENCODE, EC_R_NOT_INITIALIZED);
          return 0;
      }
  
      return BN_to_montgomery(r, a, (BN_MONT_CTX *)group->field_data1, ctx);
  }
  
  int ec_GFp_mont_field_decode(const EC_GROUP *group, BIGNUM *r,
                               const BIGNUM *a, BN_CTX *ctx)
  {
      if (group->field_data1 == NULL) {
          ECerr(EC_F_EC_GFP_MONT_FIELD_DECODE, EC_R_NOT_INITIALIZED);
          return 0;
      }
  
      return BN_from_montgomery(r, a, group->field_data1, ctx);
  }
  
  int ec_GFp_mont_field_set_to_one(const EC_GROUP *group, BIGNUM *r,
                                   BN_CTX *ctx)
  {
      if (group->field_data2 == NULL) {
          ECerr(EC_F_EC_GFP_MONT_FIELD_SET_TO_ONE, EC_R_NOT_INITIALIZED);
          return 0;
      }
  
      if (!BN_copy(r, group->field_data2))
          return 0;
      return 1;
  }
  