1/* crypto/ecdh/ech_ossl.c */ 2/* ==================================================================== 3 * Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED. 4 * 5 * The Elliptic Curve Public-Key Crypto Library (ECC Code) included 6 * herein is developed by SUN MICROSYSTEMS, INC., and is contributed 7 * to the OpenSSL project. 8 * 9 * The ECC Code is licensed pursuant to the OpenSSL open source 10 * license provided below. 11 * 12 * The ECDH software is originally written by Douglas Stebila of 13 * Sun Microsystems Laboratories. 14 * 15 */ 16/* ==================================================================== 17 * Copyright (c) 1998-2003 The OpenSSL Project. All rights reserved. 18 * 19 * Redistribution and use in source and binary forms, with or without 20 * modification, are permitted provided that the following conditions 21 * are met: 22 * 23 * 1. Redistributions of source code must retain the above copyright 24 * notice, this list of conditions and the following disclaimer. 25 * 26 * 2. Redistributions in binary form must reproduce the above copyright 27 * notice, this list of conditions and the following disclaimer in 28 * the documentation and/or other materials provided with the 29 * distribution. 30 * 31 * 3. All advertising materials mentioning features or use of this 32 * software must display the following acknowledgment: 33 * "This product includes software developed by the OpenSSL Project 34 * for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)" 35 * 36 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to 37 * endorse or promote products derived from this software without 38 * prior written permission. For written permission, please contact 39 * openssl-core@OpenSSL.org. 40 * 41 * 5. Products derived from this software may not be called "OpenSSL" 42 * nor may "OpenSSL" appear in their names without prior written 43 * permission of the OpenSSL Project. 44 * 45 * 6. Redistributions of any form whatsoever must retain the following 46 * acknowledgment: 47 * "This product includes software developed by the OpenSSL Project 48 * for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)" 49 * 50 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY 51 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 52 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 53 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR 54 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 55 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 56 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 57 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 58 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 59 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 60 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED 61 * OF THE POSSIBILITY OF SUCH DAMAGE. 62 * ==================================================================== 63 * 64 * This product includes cryptographic software written by Eric Young 65 * (eay@cryptsoft.com). This product includes software written by Tim 66 * Hudson (tjh@cryptsoft.com). 67 * 68 */ 69 70 71#include <string.h> 72#include <limits.h> 73 74#include "cryptlib.h" 75 76#include "ech_locl.h" 77#include <openssl/err.h> 78#include <openssl/sha.h> 79#include <openssl/obj_mac.h> 80#include <openssl/bn.h> 81 82static int ecdh_compute_key(void *out, size_t len, const EC_POINT *pub_key, 83 EC_KEY *ecdh, 84 void *(*KDF)(const void *in, size_t inlen, void *out, size_t *outlen)); 85 86static ECDH_METHOD openssl_ecdh_meth = { 87 "OpenSSL ECDH method", 88 ecdh_compute_key, 89#if 0 90 NULL, /* init */ 91 NULL, /* finish */ 92#endif 93 0, /* flags */ 94 NULL /* app_data */ 95}; 96 97const ECDH_METHOD *ECDH_OpenSSL(void) 98 { 99 return &openssl_ecdh_meth; 100 } 101 102 103/* This implementation is based on the following primitives in the IEEE 1363 standard: 104 * - ECKAS-DH1 105 * - ECSVDP-DH 106 * Finally an optional KDF is applied. 107 */ 108static int ecdh_compute_key(void *out, size_t outlen, const EC_POINT *pub_key, 109 EC_KEY *ecdh, 110 void *(*KDF)(const void *in, size_t inlen, void *out, size_t *outlen)) 111 { 112 BN_CTX *ctx; 113 EC_POINT *tmp=NULL; 114 BIGNUM *x=NULL, *y=NULL; 115 const BIGNUM *priv_key; 116 const EC_GROUP* group; 117 int ret= -1; 118 size_t buflen, len; 119 unsigned char *buf=NULL; 120 121 if (outlen > INT_MAX) 122 { 123 ECDHerr(ECDH_F_ECDH_COMPUTE_KEY,ERR_R_MALLOC_FAILURE); /* sort of, anyway */ 124 return -1; 125 } 126 127 if ((ctx = BN_CTX_new()) == NULL) goto err; 128 BN_CTX_start(ctx); 129 x = BN_CTX_get(ctx); 130 y = BN_CTX_get(ctx); 131 132 priv_key = EC_KEY_get0_private_key(ecdh); 133 if (priv_key == NULL) 134 { 135 ECDHerr(ECDH_F_ECDH_COMPUTE_KEY,ECDH_R_NO_PRIVATE_VALUE); 136 goto err; 137 } 138 139 group = EC_KEY_get0_group(ecdh); 140 if ((tmp=EC_POINT_new(group)) == NULL) 141 { 142 ECDHerr(ECDH_F_ECDH_COMPUTE_KEY,ERR_R_MALLOC_FAILURE); 143 goto err; 144 } 145 146 if (!EC_POINT_mul(group, tmp, NULL, pub_key, priv_key, ctx)) 147 { 148 ECDHerr(ECDH_F_ECDH_COMPUTE_KEY,ECDH_R_POINT_ARITHMETIC_FAILURE); 149 goto err; 150 } 151 152 if (EC_METHOD_get_field_type(EC_GROUP_method_of(group)) == NID_X9_62_prime_field) 153 { 154 if (!EC_POINT_get_affine_coordinates_GFp(group, tmp, x, y, ctx)) 155 { 156 ECDHerr(ECDH_F_ECDH_COMPUTE_KEY,ECDH_R_POINT_ARITHMETIC_FAILURE); 157 goto err; 158 } 159 } 160#ifndef OPENSSL_NO_EC2M 161 else 162 { 163 if (!EC_POINT_get_affine_coordinates_GF2m(group, tmp, x, y, ctx)) 164 { 165 ECDHerr(ECDH_F_ECDH_COMPUTE_KEY,ECDH_R_POINT_ARITHMETIC_FAILURE); 166 goto err; 167 } 168 } 169#endif 170 171 buflen = (EC_GROUP_get_degree(group) + 7)/8; 172 len = BN_num_bytes(x); 173 if (len > buflen) 174 { 175 ECDHerr(ECDH_F_ECDH_COMPUTE_KEY,ERR_R_INTERNAL_ERROR); 176 goto err; 177 } 178 if ((buf = OPENSSL_malloc(buflen)) == NULL) 179 { 180 ECDHerr(ECDH_F_ECDH_COMPUTE_KEY,ERR_R_MALLOC_FAILURE); 181 goto err; 182 } 183 184 memset(buf, 0, buflen - len); 185 if (len != (size_t)BN_bn2bin(x, buf + buflen - len)) 186 { 187 ECDHerr(ECDH_F_ECDH_COMPUTE_KEY,ERR_R_BN_LIB); 188 goto err; 189 } 190 191 if (KDF != 0) 192 { 193 if (KDF(buf, buflen, out, &outlen) == NULL) 194 { 195 ECDHerr(ECDH_F_ECDH_COMPUTE_KEY,ECDH_R_KDF_FAILED); 196 goto err; 197 } 198 ret = outlen; 199 } 200 else 201 { 202 /* no KDF, just copy as much as we can */ 203 if (outlen > buflen) 204 outlen = buflen; 205 memcpy(out, buf, outlen); 206 ret = outlen; 207 } 208 209err: 210 if (tmp) EC_POINT_free(tmp); 211 if (ctx) BN_CTX_end(ctx); 212 if (ctx) BN_CTX_free(ctx); 213 if (buf) OPENSSL_free(buf); 214 return(ret); 215 } 216