crypto/ec/ec_check.c

   1 /*
   2  * Copyright 2002-2020 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 /*
  11  * ECDSA low level APIs are deprecated for public use, but still ok for
  12  * internal use.
  13  */
  14 #include "internal/deprecated.h"
  15
  16 #include "ec_local.h"
  17 #include <openssl/err.h>
  18
  19 int EC_GROUP_check_named_curve(const EC_GROUP *group, int nist_only,
  20                                BN_CTX *ctx)
  21 {
  22     int nid;
  23     BN_CTX *new_ctx = NULL;
  24
  25     if (group == NULL) {
  26         ECerr(0, ERR_R_PASSED_NULL_PARAMETER);
  27         return NID_undef;
  28     }
  29
  30     if (ctx == NULL) {
  31         ctx = new_ctx = BN_CTX_new_ex(NULL);
  32         if (ctx == NULL) {
  33             ECerr(0, ERR_R_MALLOC_FAILURE);
  34             return NID_undef;
  35         }
  36     }
  37
  38     nid = ec_curve_nid_from_params(group, ctx);
  39     if (nid > 0 && nist_only && EC_curve_nid2nist(nid) == NULL)
  40         nid = NID_undef;
  41
  42     BN_CTX_free(new_ctx);
  43     return nid;
  44 }
  45
  46 int EC_GROUP_check(const EC_GROUP *group, BN_CTX *ctx)
  47 {
  48 #ifdef FIPS_MODULE
  49     /*
  50     * ECC domain parameter validation.
  51     * See SP800-56A R3 5.5.2 "Assurances of Domain-Parameter Validity" Part 1b.
  52     */
  53     return EC_GROUP_check_named_curve(group, 1, ctx) >= 0 ? 1 : 0;
  54 #else
  55     int ret = 0;
  56     const BIGNUM *order;
  57     BN_CTX *new_ctx = NULL;
  58     EC_POINT *point = NULL;
  59
  60     if (group == NULL || group->meth == NULL) {
  61         ECerr(EC_F_EC_GROUP_CHECK, ERR_R_PASSED_NULL_PARAMETER);
  62         return 0;
  63     }
  64
  65     /* Custom curves assumed to be correct */
  66     if ((group->meth->flags & EC_FLAGS_CUSTOM_CURVE) != 0)
  67         return 1;
  68
  69     if (ctx == NULL) {
  70         ctx = new_ctx = BN_CTX_new();
  71         if (ctx == NULL) {
  72             ECerr(EC_F_EC_GROUP_CHECK, ERR_R_MALLOC_FAILURE);
  73             goto err;
  74         }
  75     }
  76
  77     /* check the discriminant */
  78     if (!EC_GROUP_check_discriminant(group, ctx)) {
  79         ECerr(EC_F_EC_GROUP_CHECK, EC_R_DISCRIMINANT_IS_ZERO);
  80         goto err;
  81     }
  82
  83     /* check the generator */
  84     if (group->generator == NULL) {
  85         ECerr(EC_F_EC_GROUP_CHECK, EC_R_UNDEFINED_GENERATOR);
  86         goto err;
  87     }
  88     if (EC_POINT_is_on_curve(group, group->generator, ctx) <= 0) {
  89         ECerr(EC_F_EC_GROUP_CHECK, EC_R_POINT_IS_NOT_ON_CURVE);
  90         goto err;
  91     }
  92
  93     /* check the order of the generator */
  94     if ((point = EC_POINT_new(group)) == NULL)
  95         goto err;
  96     order = EC_GROUP_get0_order(group);
  97     if (order == NULL)
  98         goto err;
  99     if (BN_is_zero(order)) {
 100         ECerr(EC_F_EC_GROUP_CHECK, EC_R_UNDEFINED_ORDER);
 101         goto err;
 102     }
 103
 104     if (!EC_POINT_mul(group, point, order, NULL, NULL, ctx))
 105         goto err;
 106     if (!EC_POINT_is_at_infinity(group, point)) {
 107         ECerr(EC_F_EC_GROUP_CHECK, EC_R_INVALID_GROUP_ORDER);
 108         goto err;
 109     }
 110
 111     ret = 1;
 112
 113  err:
 114     BN_CTX_free(new_ctx);
 115     EC_POINT_free(point);
 116     return ret;
 117 #endif /* FIPS_MODULE */
 118 }