1 /* ==================================================================== 2 * Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED. 3 * 4 * The Elliptic Curve Public-Key Crypto Library (ECC Code) included 5 * herein is developed by SUN MICROSYSTEMS, INC., and is contributed 6 * to the OpenSSL project. 7 * 8 * The ECC Code is licensed pursuant to the OpenSSL open source 9 * license provided below. 10 * 11 * The ECDH software is originally written by Douglas Stebila of 12 * Sun Microsystems Laboratories. 13 * 14 */ 15 /* ==================================================================== 16 * Copyright (c) 2000-2002 The OpenSSL Project. All rights reserved. 17 * 18 * Redistribution and use in source and binary forms, with or without 19 * modification, are permitted provided that the following conditions 20 * are met: 21 * 22 * 1. Redistributions of source code must retain the above copyright 23 * notice, this list of conditions and the following disclaimer. 24 * 25 * 2. Redistributions in binary form must reproduce the above copyright 26 * notice, this list of conditions and the following disclaimer in 27 * the documentation and/or other materials provided with the 28 * distribution. 29 * 30 * 3. All advertising materials mentioning features or use of this 31 * software must display the following acknowledgment: 32 * "This product includes software developed by the OpenSSL Project 33 * for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)" 34 * 35 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to 36 * endorse or promote products derived from this software without 37 * prior written permission. For written permission, please contact 38 * licensing (at) OpenSSL.org. 39 * 40 * 5. Products derived from this software may not be called "OpenSSL" 41 * nor may "OpenSSL" appear in their names without prior written 42 * permission of the OpenSSL Project. 43 * 44 * 6. Redistributions of any form whatsoever must retain the following 45 * acknowledgment: 46 * "This product includes software developed by the OpenSSL Project 47 * for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)" 48 * 49 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY 50 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 51 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 52 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR 53 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 54 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 55 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 56 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 57 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 58 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 59 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED 60 * OF THE POSSIBILITY OF SUCH DAMAGE. 61 * ==================================================================== 62 * 63 * This product includes cryptographic software written by Eric Young 64 * (eay (at) cryptsoft.com). This product includes software written by Tim 65 * Hudson (tjh (at) cryptsoft.com). */ 66 67 #include <openssl/ecdh.h> 68 69 #include <limits.h> 70 #include <string.h> 71 72 #include <openssl/digest.h> 73 #include <openssl/err.h> 74 #include <openssl/mem.h> 75 76 #include "../fipsmodule/ec/internal.h" 77 #include "../internal.h" 78 79 80 int ECDH_compute_key(void *out, size_t out_len, const EC_POINT *pub_key, 81 const EC_KEY *priv_key, 82 void *(*kdf)(const void *in, size_t inlen, void *out, 83 size_t *out_len)) { 84 if (priv_key->priv_key == NULL) { 85 OPENSSL_PUT_ERROR(ECDH, ECDH_R_NO_PRIVATE_VALUE); 86 return -1; 87 } 88 const EC_SCALAR *const priv = &priv_key->priv_key->scalar; 89 const EC_GROUP *const group = EC_KEY_get0_group(priv_key); 90 if (EC_GROUP_cmp(group, pub_key->group, NULL) != 0) { 91 OPENSSL_PUT_ERROR(EC, EC_R_INCOMPATIBLE_OBJECTS); 92 return -1; 93 } 94 95 EC_RAW_POINT shared_point; 96 uint8_t buf[EC_MAX_BYTES]; 97 size_t buf_len; 98 if (!ec_point_mul_scalar(group, &shared_point, NULL, &pub_key->raw, priv) || 99 !ec_point_get_affine_coordinate_bytes(group, buf, NULL, &buf_len, 100 sizeof(buf), &shared_point)) { 101 OPENSSL_PUT_ERROR(ECDH, ECDH_R_POINT_ARITHMETIC_FAILURE); 102 return -1; 103 } 104 105 if (kdf != NULL) { 106 if (kdf(buf, buf_len, out, &out_len) == NULL) { 107 OPENSSL_PUT_ERROR(ECDH, ECDH_R_KDF_FAILED); 108 return -1; 109 } 110 } else { 111 // no KDF, just copy as much as we can 112 if (buf_len < out_len) { 113 out_len = buf_len; 114 } 115 OPENSSL_memcpy(out, buf, out_len); 116 } 117 118 if (out_len > INT_MAX) { 119 OPENSSL_PUT_ERROR(ECDH, ERR_R_OVERFLOW); 120 return -1; 121 } 122 123 return (int)out_len; 124 } 125
