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
EC_GROUP_check(const EC_GROUP * group,BN_CTX * ctx)13 int 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