blob: 4a1964a0b34d2c723667e1772a5f7f3e6ec1408f [file] [log] [blame]
Adam Langley95c29f32014-06-20 12:00:00 -07001/* ====================================================================
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@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@cryptsoft.com). This product includes software written by Tim
65 * Hudson (tjh@cryptsoft.com). */
66
67#include <openssl/ecdh.h>
68
Adam Langley2b2d66d2015-01-30 17:08:37 -080069#include <string.h>
70
Adam Langley95c29f32014-06-20 12:00:00 -070071#include <openssl/bn.h>
72#include <openssl/digest.h>
73#include <openssl/err.h>
74#include <openssl/mem.h>
75
76
77int ECDH_compute_key(void *out, size_t outlen, const EC_POINT *pub_key,
Brian Smith0dc2a8a2015-10-08 11:52:56 -100078 EC_KEY *priv_key,
79 void *(*kdf)(const void *in, size_t inlen, void *out,
80 size_t *outlen)) {
81 const BIGNUM *const priv = EC_KEY_get0_private_key(priv_key);
Adam Langley95c29f32014-06-20 12:00:00 -070082 if (priv == NULL) {
David Benjamin3570d732015-06-29 00:28:17 -040083 OPENSSL_PUT_ERROR(ECDH, ECDH_R_NO_PRIVATE_VALUE);
Brian Smith0dc2a8a2015-10-08 11:52:56 -100084 return -1;
Adam Langley95c29f32014-06-20 12:00:00 -070085 }
86
Brian Smith0dc2a8a2015-10-08 11:52:56 -100087 BN_CTX *ctx = BN_CTX_new();
88 if (ctx == NULL) {
89 return -1;
90 }
91 BN_CTX_start(ctx);
Adam Langley95c29f32014-06-20 12:00:00 -070092
Brian Smith0dc2a8a2015-10-08 11:52:56 -100093 int ret = -1;
94 size_t buflen = 0;
95 uint8_t *buf = NULL;
96
97 const EC_GROUP *const group = EC_KEY_get0_group(priv_key);
98 EC_POINT *tmp = EC_POINT_new(group);
Adam Langley95c29f32014-06-20 12:00:00 -070099 if (tmp == NULL) {
David Benjamin3570d732015-06-29 00:28:17 -0400100 OPENSSL_PUT_ERROR(ECDH, ERR_R_MALLOC_FAILURE);
Adam Langley95c29f32014-06-20 12:00:00 -0700101 goto err;
102 }
103
104 if (!EC_POINT_mul(group, tmp, NULL, pub_key, priv, ctx)) {
David Benjamin3570d732015-06-29 00:28:17 -0400105 OPENSSL_PUT_ERROR(ECDH, ECDH_R_POINT_ARITHMETIC_FAILURE);
Adam Langley95c29f32014-06-20 12:00:00 -0700106 goto err;
107 }
108
Brian Smith0dc2a8a2015-10-08 11:52:56 -1000109 BIGNUM *x = BN_CTX_get(ctx);
110 if (!x) {
111 OPENSSL_PUT_ERROR(ECDH, ERR_R_MALLOC_FAILURE);
112 goto err;
113 }
114
115 if (!EC_POINT_get_affine_coordinates_GFp(group, tmp, x, NULL, ctx)) {
David Benjamin3570d732015-06-29 00:28:17 -0400116 OPENSSL_PUT_ERROR(ECDH, ECDH_R_POINT_ARITHMETIC_FAILURE);
Adam Langley95c29f32014-06-20 12:00:00 -0700117 goto err;
118 }
119
120 buflen = (EC_GROUP_get_degree(group) + 7) / 8;
Adam Langley95c29f32014-06-20 12:00:00 -0700121 buf = OPENSSL_malloc(buflen);
122 if (buf == NULL) {
David Benjamin3570d732015-06-29 00:28:17 -0400123 OPENSSL_PUT_ERROR(ECDH, ERR_R_MALLOC_FAILURE);
Adam Langley95c29f32014-06-20 12:00:00 -0700124 goto err;
125 }
126
David Benjaminf2f3cfe2014-11-10 17:28:53 -0500127 if (!BN_bn2bin_padded(buf, buflen, x)) {
David Benjamin3570d732015-06-29 00:28:17 -0400128 OPENSSL_PUT_ERROR(ECDH, ERR_R_INTERNAL_ERROR);
Adam Langley95c29f32014-06-20 12:00:00 -0700129 goto err;
130 }
131
Brian Smith0dc2a8a2015-10-08 11:52:56 -1000132 if (kdf != NULL) {
133 if (kdf(buf, buflen, out, &outlen) == NULL) {
David Benjamin3570d732015-06-29 00:28:17 -0400134 OPENSSL_PUT_ERROR(ECDH, ECDH_R_KDF_FAILED);
Adam Langley95c29f32014-06-20 12:00:00 -0700135 goto err;
136 }
Adam Langley95c29f32014-06-20 12:00:00 -0700137 } else {
138 /* no KDF, just copy as much as we can */
Brian Smith0dc2a8a2015-10-08 11:52:56 -1000139 if (buflen < outlen) {
Adam Langley95c29f32014-06-20 12:00:00 -0700140 outlen = buflen;
141 }
142 memcpy(out, buf, outlen);
Adam Langley95c29f32014-06-20 12:00:00 -0700143 }
144
Brian Smith0dc2a8a2015-10-08 11:52:56 -1000145 ret = outlen;
146
Adam Langley95c29f32014-06-20 12:00:00 -0700147err:
Brian Smith0dc2a8a2015-10-08 11:52:56 -1000148 OPENSSL_free(buf);
149 EC_POINT_free(tmp);
150 BN_CTX_end(ctx);
151 BN_CTX_free(ctx);
Adam Langley95c29f32014-06-20 12:00:00 -0700152 return ret;
153}