1 /* $OpenBSD: ec_check.c,v 1.4 2014/07/12 16:03:37 miod 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 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 ECerr(EC_F_EC_GROUP_CHECK, 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 ECerr(EC_F_EC_GROUP_CHECK, EC_R_DISCRIMINANT_IS_ZERO); 81 goto err; 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 /* 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 ECerr(EC_F_EC_GROUP_CHECK, 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 ECerr(EC_F_EC_GROUP_CHECK, 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