ec_check.c revision 296465 
1/* crypto/ec/ec_check.c */
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
59int EC_GROUP_check(const EC_GROUP *group, BN_CTX *ctx)
60{
61    int ret = 0;
62    BIGNUM *order;
63    BN_CTX *new_ctx = NULL;
64    EC_POINT *point = NULL;
65
66    if (ctx == NULL) {
67        ctx = new_ctx = BN_CTX_new();
68        if (ctx == NULL) {
69            ECerr(EC_F_EC_GROUP_CHECK, ERR_R_MALLOC_FAILURE);
70            goto err;
71        }
72    }
73    BN_CTX_start(ctx);
74    if ((order = BN_CTX_get(ctx)) == NULL)
75        goto err;
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    if (!EC_GROUP_get_order(group, order, ctx))
97        goto err;
98    if (BN_is_zero(order)) {
99        ECerr(EC_F_EC_GROUP_CHECK, EC_R_UNDEFINED_ORDER);
100        goto err;
101    }
102
103    if (!EC_POINT_mul(group, point, order, NULL, NULL, ctx))
104        goto err;
105    if (!EC_POINT_is_at_infinity(group, point)) {
106        ECerr(EC_F_EC_GROUP_CHECK, EC_R_INVALID_GROUP_ORDER);
107        goto err;
108    }
109
110    ret = 1;
111
112 err:
113    if (ctx != NULL)
114        BN_CTX_end(ctx);
115    if (new_ctx != NULL)
116        BN_CTX_free(new_ctx);
117    if (point)
118        EC_POINT_free(point);
119    return ret;
120}
121