1/*
2 * Copyright 2002-2016 The OpenSSL Project Authors. All Rights Reserved.
3 *
4 * Licensed under the OpenSSL license (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_local.h"
11#include <openssl/err.h>
12
13int EC_GROUP_check(const EC_GROUP *group, BN_CTX *ctx)
14{
15    int ret = 0;
16    const BIGNUM *order;
17    BN_CTX *new_ctx = NULL;
18    EC_POINT *point = NULL;
19
20    /* Custom curves assumed to be correct */
21    if ((group->meth->flags & EC_FLAGS_CUSTOM_CURVE) != 0)
22        return 1;
23
24    if (ctx == NULL) {
25        ctx = new_ctx = BN_CTX_new();
26        if (ctx == NULL) {
27            ECerr(EC_F_EC_GROUP_CHECK, ERR_R_MALLOC_FAILURE);
28            goto err;
29        }
30    }
31
32    /* check the discriminant */
33    if (!EC_GROUP_check_discriminant(group, ctx)) {
34        ECerr(EC_F_EC_GROUP_CHECK, EC_R_DISCRIMINANT_IS_ZERO);
35        goto err;
36    }
37
38    /* check the generator */
39    if (group->generator == NULL) {
40        ECerr(EC_F_EC_GROUP_CHECK, EC_R_UNDEFINED_GENERATOR);
41        goto err;
42    }
43    if (EC_POINT_is_on_curve(group, group->generator, ctx) <= 0) {
44        ECerr(EC_F_EC_GROUP_CHECK, EC_R_POINT_IS_NOT_ON_CURVE);
45        goto err;
46    }
47
48    /* check the order of the generator */
49    if ((point = EC_POINT_new(group)) == NULL)
50        goto err;
51    order = EC_GROUP_get0_order(group);
52    if (order == NULL)
53        goto err;
54    if (BN_is_zero(order)) {
55        ECerr(EC_F_EC_GROUP_CHECK, EC_R_UNDEFINED_ORDER);
56        goto err;
57    }
58
59    if (!EC_POINT_mul(group, point, order, NULL, NULL, ctx))
60        goto err;
61    if (!EC_POINT_is_at_infinity(group, point)) {
62        ECerr(EC_F_EC_GROUP_CHECK, EC_R_INVALID_GROUP_ORDER);
63        goto err;
64    }
65
66    ret = 1;
67
68 err:
69    BN_CTX_free(new_ctx);
70    EC_POINT_free(point);
71    return ret;
72}
73