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e172d60d BM |
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 | * | |
e172d60d BM |
12 | * The ECDH software is originally written by Douglas Stebila of |
13 | * Sun Microsystems Laboratories. | |
14 | * | |
15 | */ | |
16 | /* ==================================================================== | |
66c236c4 | 17 | * Copyright (c) 1998-2019 The OpenSSL Project. All rights reserved. |
e172d60d BM |
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 | |
ae5c8664 | 24 | * notice, this list of conditions and the following disclaimer. |
e172d60d BM |
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 | ||
8b5bcef7 | 70 | #include <string.h> |
176f31dd BM |
71 | #include <limits.h> |
72 | ||
10a66ad3 DSH |
73 | #include "cryptlib.h" |
74 | ||
6a50d0a4 | 75 | #include "ech_locl.h" |
e172d60d BM |
76 | #include <openssl/err.h> |
77 | #include <openssl/sha.h> | |
78 | #include <openssl/obj_mac.h> | |
0f814687 | 79 | #include <openssl/bn.h> |
e172d60d | 80 | |
965a1cb9 | 81 | static int ecdh_compute_key(void *out, size_t len, const EC_POINT *pub_key, |
ae5c8664 MC |
82 | EC_KEY *ecdh, |
83 | void *(*KDF) (const void *in, size_t inlen, | |
84 | void *out, size_t *outlen)); | |
e172d60d BM |
85 | |
86 | static ECDH_METHOD openssl_ecdh_meth = { | |
ae5c8664 MC |
87 | "OpenSSL ECDH method", |
88 | ecdh_compute_key, | |
e172d60d | 89 | #if 0 |
ae5c8664 MC |
90 | NULL, /* init */ |
91 | NULL, /* finish */ | |
e172d60d | 92 | #endif |
ae5c8664 MC |
93 | 0, /* flags */ |
94 | NULL /* app_data */ | |
e172d60d BM |
95 | }; |
96 | ||
97 | const ECDH_METHOD *ECDH_OpenSSL(void) | |
ae5c8664 MC |
98 | { |
99 | return &openssl_ecdh_meth; | |
100 | } | |
e172d60d | 101 | |
e19d4a99 MC |
102 | /*- |
103 | * This implementation is based on the following primitives in the IEEE 1363 standard: | |
e172d60d BM |
104 | * - ECKAS-DH1 |
105 | * - ECSVDP-DH | |
176f31dd | 106 | * Finally an optional KDF is applied. |
e172d60d | 107 | */ |
965a1cb9 | 108 | static int ecdh_compute_key(void *out, size_t outlen, const EC_POINT *pub_key, |
ae5c8664 MC |
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 | if (outlen > INT_MAX) { | |
123 | ECDHerr(ECDH_F_ECDH_COMPUTE_KEY, ERR_R_MALLOC_FAILURE); /* sort of, | |
124 | * anyway */ | |
125 | return -1; | |
126 | } | |
127 | ||
128 | if ((ctx = BN_CTX_new()) == NULL) | |
129 | goto err; | |
130 | BN_CTX_start(ctx); | |
131 | x = BN_CTX_get(ctx); | |
132 | y = BN_CTX_get(ctx); | |
133 | ||
134 | priv_key = EC_KEY_get0_private_key(ecdh); | |
135 | if (priv_key == NULL) { | |
136 | ECDHerr(ECDH_F_ECDH_COMPUTE_KEY, ECDH_R_NO_PRIVATE_VALUE); | |
137 | goto err; | |
138 | } | |
139 | ||
140 | group = EC_KEY_get0_group(ecdh); | |
141 | ||
142 | if (EC_KEY_get_flags(ecdh) & EC_FLAG_COFACTOR_ECDH) { | |
143 | if (!EC_GROUP_get_cofactor(group, x, ctx) || | |
144 | !BN_mul(x, x, priv_key, ctx)) { | |
145 | ECDHerr(ECDH_F_ECDH_COMPUTE_KEY, ERR_R_MALLOC_FAILURE); | |
146 | goto err; | |
147 | } | |
148 | priv_key = x; | |
149 | } | |
150 | ||
151 | if ((tmp = EC_POINT_new(group)) == NULL) { | |
152 | ECDHerr(ECDH_F_ECDH_COMPUTE_KEY, ERR_R_MALLOC_FAILURE); | |
153 | goto err; | |
154 | } | |
155 | ||
156 | if (!EC_POINT_mul(group, tmp, NULL, pub_key, priv_key, ctx)) { | |
157 | ECDHerr(ECDH_F_ECDH_COMPUTE_KEY, ECDH_R_POINT_ARITHMETIC_FAILURE); | |
158 | goto err; | |
159 | } | |
160 | ||
161 | if (EC_METHOD_get_field_type(EC_GROUP_method_of(group)) == | |
162 | NID_X9_62_prime_field) { | |
163 | if (!EC_POINT_get_affine_coordinates_GFp(group, tmp, x, y, ctx)) { | |
164 | ECDHerr(ECDH_F_ECDH_COMPUTE_KEY, ECDH_R_POINT_ARITHMETIC_FAILURE); | |
165 | goto err; | |
166 | } | |
167 | } | |
f610a516 | 168 | #ifndef OPENSSL_NO_EC2M |
ae5c8664 MC |
169 | else { |
170 | if (!EC_POINT_get_affine_coordinates_GF2m(group, tmp, x, y, ctx)) { | |
171 | ECDHerr(ECDH_F_ECDH_COMPUTE_KEY, ECDH_R_POINT_ARITHMETIC_FAILURE); | |
172 | goto err; | |
173 | } | |
174 | } | |
f610a516 | 175 | #endif |
e172d60d | 176 | |
ae5c8664 MC |
177 | buflen = (EC_GROUP_get_degree(group) + 7) / 8; |
178 | len = BN_num_bytes(x); | |
179 | if (len > buflen) { | |
180 | ECDHerr(ECDH_F_ECDH_COMPUTE_KEY, ERR_R_INTERNAL_ERROR); | |
181 | goto err; | |
182 | } | |
183 | if ((buf = OPENSSL_malloc(buflen)) == NULL) { | |
184 | ECDHerr(ECDH_F_ECDH_COMPUTE_KEY, ERR_R_MALLOC_FAILURE); | |
185 | goto err; | |
186 | } | |
187 | ||
188 | memset(buf, 0, buflen - len); | |
189 | if (len != (size_t)BN_bn2bin(x, buf + buflen - len)) { | |
190 | ECDHerr(ECDH_F_ECDH_COMPUTE_KEY, ERR_R_BN_LIB); | |
191 | goto err; | |
192 | } | |
193 | ||
194 | if (KDF != 0) { | |
195 | if (KDF(buf, buflen, out, &outlen) == NULL) { | |
196 | ECDHerr(ECDH_F_ECDH_COMPUTE_KEY, ECDH_R_KDF_FAILED); | |
197 | goto err; | |
198 | } | |
199 | ret = outlen; | |
200 | } else { | |
201 | /* no KDF, just copy as much as we can */ | |
202 | if (outlen > buflen) | |
203 | outlen = buflen; | |
204 | memcpy(out, buf, outlen); | |
205 | ret = outlen; | |
206 | } | |
207 | ||
208 | err: | |
209 | if (tmp) | |
dbf71ae4 | 210 | EC_POINT_clear_free(tmp); |
ae5c8664 MC |
211 | if (ctx) |
212 | BN_CTX_end(ctx); | |
213 | if (ctx) | |
214 | BN_CTX_free(ctx); | |
0e469016 DMSP |
215 | if (buf) { |
216 | OPENSSL_cleanse(buf, buflen); | |
ae5c8664 | 217 | OPENSSL_free(buf); |
0e469016 | 218 | } |
ae5c8664 MC |
219 | return (ret); |
220 | } |