Line data Source code
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 : #include <string.h>
71 : #include <limits.h>
72 :
73 : #include "cryptlib.h"
74 :
75 : #include "ech_locl.h"
76 : #include <openssl/err.h>
77 : #include <openssl/sha.h>
78 : #include <openssl/obj_mac.h>
79 : #include <openssl/bn.h>
80 :
81 : static int ecdh_compute_key(void *out, size_t len, const EC_POINT *pub_key,
82 : EC_KEY *ecdh,
83 : void *(*KDF) (const void *in, size_t inlen,
84 : void *out, size_t *outlen));
85 :
86 : static 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 :
97 100 : const ECDH_METHOD *ECDH_OpenSSL(void)
98 : {
99 100 : 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 : */
108 737 : static 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,
111 : void *out, size_t *outlen))
112 : {
113 : BN_CTX *ctx;
114 : EC_POINT *tmp = NULL;
115 : BIGNUM *x = NULL, *y = NULL;
116 : const BIGNUM *priv_key;
117 : const EC_GROUP *group;
118 : int ret = -1;
119 : size_t buflen, len;
120 : unsigned char *buf = NULL;
121 :
122 737 : if (outlen > INT_MAX) {
123 0 : ECDHerr(ECDH_F_ECDH_COMPUTE_KEY, ERR_R_MALLOC_FAILURE); /* sort of,
124 : * anyway */
125 0 : return -1;
126 : }
127 :
128 737 : if ((ctx = BN_CTX_new()) == NULL)
129 : goto err;
130 737 : BN_CTX_start(ctx);
131 737 : x = BN_CTX_get(ctx);
132 737 : y = BN_CTX_get(ctx);
133 :
134 737 : priv_key = EC_KEY_get0_private_key(ecdh);
135 737 : if (priv_key == NULL) {
136 0 : ECDHerr(ECDH_F_ECDH_COMPUTE_KEY, ECDH_R_NO_PRIVATE_VALUE);
137 0 : goto err;
138 : }
139 :
140 737 : group = EC_KEY_get0_group(ecdh);
141 :
142 737 : if (EC_KEY_get_flags(ecdh) & EC_FLAG_COFACTOR_ECDH) {
143 0 : if (!EC_GROUP_get_cofactor(group, x, ctx) ||
144 0 : !BN_mul(x, x, priv_key, ctx)) {
145 0 : ECDHerr(ECDH_F_ECDH_COMPUTE_KEY, ERR_R_MALLOC_FAILURE);
146 0 : goto err;
147 : }
148 : priv_key = x;
149 : }
150 :
151 737 : if ((tmp = EC_POINT_new(group)) == NULL) {
152 0 : ECDHerr(ECDH_F_ECDH_COMPUTE_KEY, ERR_R_MALLOC_FAILURE);
153 0 : goto err;
154 : }
155 :
156 737 : if (!EC_POINT_mul(group, tmp, NULL, pub_key, priv_key, ctx)) {
157 0 : ECDHerr(ECDH_F_ECDH_COMPUTE_KEY, ECDH_R_POINT_ARITHMETIC_FAILURE);
158 0 : goto err;
159 : }
160 :
161 737 : if (EC_METHOD_get_field_type(EC_GROUP_method_of(group)) ==
162 : NID_X9_62_prime_field) {
163 737 : if (!EC_POINT_get_affine_coordinates_GFp(group, tmp, x, y, ctx)) {
164 0 : ECDHerr(ECDH_F_ECDH_COMPUTE_KEY, ECDH_R_POINT_ARITHMETIC_FAILURE);
165 0 : goto err;
166 : }
167 : }
168 : #ifndef OPENSSL_NO_EC2M
169 : else {
170 0 : if (!EC_POINT_get_affine_coordinates_GF2m(group, tmp, x, y, ctx)) {
171 0 : ECDHerr(ECDH_F_ECDH_COMPUTE_KEY, ECDH_R_POINT_ARITHMETIC_FAILURE);
172 0 : goto err;
173 : }
174 : }
175 : #endif
176 :
177 737 : buflen = (EC_GROUP_get_degree(group) + 7) / 8;
178 737 : len = BN_num_bytes(x);
179 737 : if (len > buflen) {
180 0 : ECDHerr(ECDH_F_ECDH_COMPUTE_KEY, ERR_R_INTERNAL_ERROR);
181 0 : goto err;
182 : }
183 737 : if ((buf = OPENSSL_malloc(buflen)) == NULL) {
184 0 : ECDHerr(ECDH_F_ECDH_COMPUTE_KEY, ERR_R_MALLOC_FAILURE);
185 0 : goto err;
186 : }
187 :
188 737 : memset(buf, 0, buflen - len);
189 737 : if (len != (size_t)BN_bn2bin(x, buf + buflen - len)) {
190 0 : ECDHerr(ECDH_F_ECDH_COMPUTE_KEY, ERR_R_BN_LIB);
191 0 : goto err;
192 : }
193 :
194 737 : if (KDF != 0) {
195 0 : if (KDF(buf, buflen, out, &outlen) == NULL) {
196 0 : ECDHerr(ECDH_F_ECDH_COMPUTE_KEY, ECDH_R_KDF_FAILED);
197 0 : goto err;
198 : }
199 0 : ret = outlen;
200 : } else {
201 : /* no KDF, just copy as much as we can */
202 737 : if (outlen > buflen)
203 0 : outlen = buflen;
204 737 : memcpy(out, buf, outlen);
205 737 : ret = outlen;
206 : }
207 :
208 : err:
209 737 : if (tmp)
210 737 : EC_POINT_free(tmp);
211 737 : if (ctx)
212 737 : BN_CTX_end(ctx);
213 737 : if (ctx)
214 737 : BN_CTX_free(ctx);
215 737 : if (buf)
216 737 : OPENSSL_free(buf);
217 737 : return (ret);
218 : }
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