1 /* $OpenBSD: ec_check.c,v 1.9 2018/07/15 16:27:39 tb Exp $ */
2 /* ====================================================================
3 * Copyright (c) 1998-2002 The OpenSSL Project. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 *
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 *
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in
14 * the documentation and/or other materials provided with the
15 * distribution.
16 *
17 * 3. All advertising materials mentioning features or use of this
18 * software must display the following acknowledgment:
19 * "This product includes software developed by the OpenSSL Project
20 * for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
21 *
22 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
23 * endorse or promote products derived from this software without
24 * prior written permission. For written permission, please contact
25 * openssl-core@openssl.org.
26 *
27 * 5. Products derived from this software may not be called "OpenSSL"
28 * nor may "OpenSSL" appear in their names without prior written
29 * permission of the OpenSSL Project.
30 *
31 * 6. Redistributions of any form whatsoever must retain the following
32 * acknowledgment:
33 * "This product includes software developed by the OpenSSL Project
34 * for use in the OpenSSL Toolkit (http://www.openssl.org/)"
35 *
36 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
37 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
38 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
39 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
40 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
41 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
42 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
43 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
44 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
45 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
46 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
47 * OF THE POSSIBILITY OF SUCH DAMAGE.
48 * ====================================================================
49 *
50 * This product includes cryptographic software written by Eric Young
51 * (eay@cryptsoft.com). This product includes software written by Tim
52 * Hudson (tjh@cryptsoft.com).
53 *
54 */
55
56 #include "ec_lcl.h"
57 #include <openssl/err.h>
58
59 int
EC_GROUP_check(const EC_GROUP * group,BN_CTX * ctx)60 EC_GROUP_check(const EC_GROUP * group, BN_CTX * ctx)
61 {
62 int ret = 0;
63 BIGNUM *order;
64 BN_CTX *new_ctx = NULL;
65 EC_POINT *point = NULL;
66
67 if (ctx == NULL) {
68 ctx = new_ctx = BN_CTX_new();
69 if (ctx == NULL) {
70 ECerror(ERR_R_MALLOC_FAILURE);
71 goto err;
72 }
73 }
74 BN_CTX_start(ctx);
75 if ((order = BN_CTX_get(ctx)) == NULL)
76 goto err;
77
78 /* check the discriminant */
79 if (!EC_GROUP_check_discriminant(group, ctx)) {
80 ECerror(EC_R_DISCRIMINANT_IS_ZERO);
81 goto err;
82 }
83 /* check the generator */
84 if (group->generator == NULL) {
85 ECerror(EC_R_UNDEFINED_GENERATOR);
86 goto err;
87 }
88 if (EC_POINT_is_on_curve(group, group->generator, ctx) <= 0) {
89 ECerror(EC_R_POINT_IS_NOT_ON_CURVE);
90 goto err;
91 }
92 /* check the order of the generator */
93 if ((point = EC_POINT_new(group)) == NULL)
94 goto err;
95 if (!EC_GROUP_get_order(group, order, ctx))
96 goto err;
97 if (BN_is_zero(order)) {
98 ECerror(EC_R_UNDEFINED_ORDER);
99 goto err;
100 }
101 if (!EC_POINT_mul(group, point, order, NULL, NULL, ctx))
102 goto err;
103 if (EC_POINT_is_at_infinity(group, point) <= 0) {
104 ECerror(EC_R_INVALID_GROUP_ORDER);
105 goto err;
106 }
107 ret = 1;
108
109 err:
110 if (ctx != NULL)
111 BN_CTX_end(ctx);
112 BN_CTX_free(new_ctx);
113 EC_POINT_free(point);
114 return ret;
115 }
116