crypto/ec/ec_check.c

   1 /*
   2  * Copyright 2002-2019 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the Apache License 2.0 (the "License").  You may not use
   5  * this file except in compliance with the License.  You can obtain a copy
   6  * in the file LICENSE in the source distribution or at
   7  * https://www.openssl.org/source/license.html
   8  */
   9
  10 #include "ec_lcl.h"
  11 #include <openssl/err.h>
  12
  13 int EC_GROUP_check_named_curve(const EC_GROUP *group, int nist_only)
  14 {
  15     int nid;
  16
  17     nid = ec_curve_nid_from_params(group);
  18     if (nid > 0 && nist_only && EC_curve_nid2nist(nid) == NULL)
  19         nid = 0;
  20     return nid;
  21 }
  22
  23 int EC_GROUP_check(const EC_GROUP *group, BN_CTX *ctx)
  24 {
  25     int ret = 0;
  26     const BIGNUM *order;
  27     BN_CTX *new_ctx = NULL;
  28     EC_POINT *point = NULL;
  29
  30     if (group == NULL || group->meth == NULL) {
  31         ECerr(EC_F_EC_GROUP_CHECK, ERR_R_PASSED_NULL_PARAMETER);
  32         return 0;
  33     }
  34
  35     /* Custom curves assumed to be correct */
  36     if ((group->meth->flags & EC_FLAGS_CUSTOM_CURVE) != 0)
  37         return 1;
  38
  39     if (ctx == NULL) {
  40         ctx = new_ctx = BN_CTX_new();
  41         if (ctx == NULL) {
  42             ECerr(EC_F_EC_GROUP_CHECK, ERR_R_MALLOC_FAILURE);
  43             goto err;
  44         }
  45     }
  46
  47     /* check the discriminant */
  48     if (!EC_GROUP_check_discriminant(group, ctx)) {
  49         ECerr(EC_F_EC_GROUP_CHECK, EC_R_DISCRIMINANT_IS_ZERO);
  50         goto err;
  51     }
  52
  53     /* check the generator */
  54     if (group->generator == NULL) {
  55         ECerr(EC_F_EC_GROUP_CHECK, EC_R_UNDEFINED_GENERATOR);
  56         goto err;
  57     }
  58     if (EC_POINT_is_on_curve(group, group->generator, ctx) <= 0) {
  59         ECerr(EC_F_EC_GROUP_CHECK, EC_R_POINT_IS_NOT_ON_CURVE);
  60         goto err;
  61     }
  62
  63     /* check the order of the generator */
  64     if ((point = EC_POINT_new(group)) == NULL)
  65         goto err;
  66     order = EC_GROUP_get0_order(group);
  67     if (order == NULL)
  68         goto err;
  69     if (BN_is_zero(order)) {
  70         ECerr(EC_F_EC_GROUP_CHECK, EC_R_UNDEFINED_ORDER);
  71         goto err;
  72     }
  73
  74     if (!EC_POINT_mul(group, point, order, NULL, NULL, ctx))
  75         goto err;
  76     if (!EC_POINT_is_at_infinity(group, point)) {
  77         ECerr(EC_F_EC_GROUP_CHECK, EC_R_INVALID_GROUP_ORDER);
  78         goto err;
  79     }
  80
  81     ret = 1;
  82
  83  err:
  84     BN_CTX_free(new_ctx);
  85     EC_POINT_free(point);
  86     return ret;
  87 }