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
EC_GROUP_check(const EC_GROUP * group,BN_CTX * ctx)59 int 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 {
68 ctx = new_ctx = BN_CTX_new();
69 if (ctx == NULL)
70 {
71 ECerr(EC_F_EC_GROUP_CHECK, ERR_R_MALLOC_FAILURE);
72 goto err;
73 }
74 }
75 BN_CTX_start(ctx);
76 if ((order = BN_CTX_get(ctx)) == NULL) goto err;
77
78 /* check the discriminant */
79 if (!EC_GROUP_check_discriminant(group, ctx))
80 {
81 ECerr(EC_F_EC_GROUP_CHECK, EC_R_DISCRIMINANT_IS_ZERO);
82 goto err;
83 }
84
85 /* check the generator */
86 if (group->generator == NULL)
87 {
88 ECerr(EC_F_EC_GROUP_CHECK, EC_R_UNDEFINED_GENERATOR);
89 goto err;
90 }
91 if (!EC_POINT_is_on_curve(group, group->generator, ctx))
92 {
93 ECerr(EC_F_EC_GROUP_CHECK, EC_R_POINT_IS_NOT_ON_CURVE);
94 goto err;
95 }
96
97 /* check the order of the generator */
98 if ((point = EC_POINT_new(group)) == NULL) goto err;
99 if (!EC_GROUP_get_order(group, order, ctx)) goto err;
100 if (BN_is_zero(order))
101 {
102 ECerr(EC_F_EC_GROUP_CHECK, EC_R_UNDEFINED_ORDER);
103 goto err;
104 }
105
106 if (!EC_POINT_mul(group, point, order, NULL, NULL, ctx)) goto err;
107 if (!EC_POINT_is_at_infinity(group, point))
108 {
109 ECerr(EC_F_EC_GROUP_CHECK, EC_R_INVALID_GROUP_ORDER);
110 goto err;
111 }
112
113 ret = 1;
114
115 err:
116 if (ctx != NULL)
117 BN_CTX_end(ctx);
118 if (new_ctx != NULL)
119 BN_CTX_free(new_ctx);
120 if (point)
121 EC_POINT_free(point);
122 return ret;
123 }
124