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
82 static 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
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
ECDH_OpenSSL(void)97 const 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 */
ecdh_compute_key(void * out,size_t outlen,const EC_POINT * pub_key,EC_KEY * ecdh,void * (* KDF)(const void * in,size_t inlen,void * out,size_t * outlen))108 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, 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
209 err:
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