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 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