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Commit | Line | Data |
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4f22f405 RS |
1 | /* |
2 | * Copyright 2002-2016 The OpenSSL Project Authors. All Rights Reserved. | |
3 | * | |
4 | * Licensed under the OpenSSL license (the "License"). You may not use | |
5 | * this file except in compliance with the License. You can obtain a copy | |
6 | * in the file LICENSE in the source distribution or at | |
7 | * https://www.openssl.org/source/license.html | |
8 | */ | |
9 | ||
e172d60d BM |
10 | /* ==================================================================== |
11 | * Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED. | |
12 | * | |
13 | * The Elliptic Curve Public-Key Crypto Library (ECC Code) included | |
14 | * herein is developed by SUN MICROSYSTEMS, INC., and is contributed | |
15 | * to the OpenSSL project. | |
16 | * | |
17 | * The ECC Code is licensed pursuant to the OpenSSL open source | |
18 | * license provided below. | |
19 | * | |
e172d60d BM |
20 | * The ECDH software is originally written by Douglas Stebila of |
21 | * Sun Microsystems Laboratories. | |
22 | * | |
23 | */ | |
e172d60d | 24 | |
8b5bcef7 | 25 | #include <string.h> |
176f31dd BM |
26 | #include <limits.h> |
27 | ||
b39fc560 | 28 | #include "internal/cryptlib.h" |
10a66ad3 | 29 | |
e172d60d | 30 | #include <openssl/err.h> |
0f814687 | 31 | #include <openssl/bn.h> |
647b2238 DSH |
32 | #include <openssl/objects.h> |
33 | #include <openssl/ec.h> | |
34 | #include "ec_lcl.h" | |
e172d60d | 35 | |
e2285d87 DSH |
36 | int ossl_ecdh_compute_key(unsigned char **psec, size_t *pseclen, |
37 | const EC_POINT *pub_key, const EC_KEY *ecdh) | |
77470e98 | 38 | { |
9ff9bccc DSH |
39 | if (ecdh->group->meth->ecdh_compute_key == NULL) { |
40 | ECerr(EC_F_OSSL_ECDH_COMPUTE_KEY, EC_R_CURVE_DOES_NOT_SUPPORT_ECDH); | |
65ea288d | 41 | return 0; |
77470e98 DSH |
42 | } |
43 | ||
e2285d87 | 44 | return ecdh->group->meth->ecdh_compute_key(psec, pseclen, pub_key, ecdh); |
77470e98 DSH |
45 | } |
46 | ||
3a83462d MC |
47 | /*- |
48 | * This implementation is based on the following primitives in the IEEE 1363 standard: | |
e172d60d BM |
49 | * - ECKAS-DH1 |
50 | * - ECSVDP-DH | |
e172d60d | 51 | */ |
e2285d87 DSH |
52 | int ecdh_simple_compute_key(unsigned char **pout, size_t *poutlen, |
53 | const EC_POINT *pub_key, const EC_KEY *ecdh) | |
0f113f3e MC |
54 | { |
55 | BN_CTX *ctx; | |
56 | EC_POINT *tmp = NULL; | |
57 | BIGNUM *x = NULL, *y = NULL; | |
58 | const BIGNUM *priv_key; | |
59 | const EC_GROUP *group; | |
e2285d87 | 60 | int ret = 0; |
0f113f3e MC |
61 | size_t buflen, len; |
62 | unsigned char *buf = NULL; | |
63 | ||
0f113f3e MC |
64 | if ((ctx = BN_CTX_new()) == NULL) |
65 | goto err; | |
66 | BN_CTX_start(ctx); | |
67 | x = BN_CTX_get(ctx); | |
68 | y = BN_CTX_get(ctx); | |
abea494c BE |
69 | if (y == NULL) { |
70 | ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY, ERR_R_MALLOC_FAILURE); | |
71 | goto err; | |
72 | } | |
0f113f3e MC |
73 | |
74 | priv_key = EC_KEY_get0_private_key(ecdh); | |
75 | if (priv_key == NULL) { | |
77470e98 | 76 | ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY, EC_R_NO_PRIVATE_VALUE); |
0f113f3e MC |
77 | goto err; |
78 | } | |
79 | ||
80 | group = EC_KEY_get0_group(ecdh); | |
81 | ||
82 | if (EC_KEY_get_flags(ecdh) & EC_FLAG_COFACTOR_ECDH) { | |
a773b52a | 83 | if (!EC_GROUP_get_cofactor(group, x, NULL) || |
0f113f3e | 84 | !BN_mul(x, x, priv_key, ctx)) { |
77470e98 | 85 | ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY, ERR_R_MALLOC_FAILURE); |
0f113f3e MC |
86 | goto err; |
87 | } | |
88 | priv_key = x; | |
89 | } | |
90 | ||
91 | if ((tmp = EC_POINT_new(group)) == NULL) { | |
77470e98 | 92 | ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY, ERR_R_MALLOC_FAILURE); |
0f113f3e MC |
93 | goto err; |
94 | } | |
95 | ||
96 | if (!EC_POINT_mul(group, tmp, NULL, pub_key, priv_key, ctx)) { | |
77470e98 | 97 | ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY, EC_R_POINT_ARITHMETIC_FAILURE); |
0f113f3e MC |
98 | goto err; |
99 | } | |
100 | ||
101 | if (EC_METHOD_get_field_type(EC_GROUP_method_of(group)) == | |
102 | NID_X9_62_prime_field) { | |
103 | if (!EC_POINT_get_affine_coordinates_GFp(group, tmp, x, y, ctx)) { | |
77470e98 | 104 | ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY, EC_R_POINT_ARITHMETIC_FAILURE); |
0f113f3e MC |
105 | goto err; |
106 | } | |
107 | } | |
b3310161 | 108 | #ifndef OPENSSL_NO_EC2M |
0f113f3e MC |
109 | else { |
110 | if (!EC_POINT_get_affine_coordinates_GF2m(group, tmp, x, y, ctx)) { | |
77470e98 | 111 | ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY, EC_R_POINT_ARITHMETIC_FAILURE); |
0f113f3e MC |
112 | goto err; |
113 | } | |
114 | } | |
b3310161 | 115 | #endif |
e172d60d | 116 | |
0f113f3e MC |
117 | buflen = (EC_GROUP_get_degree(group) + 7) / 8; |
118 | len = BN_num_bytes(x); | |
119 | if (len > buflen) { | |
77470e98 | 120 | ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY, ERR_R_INTERNAL_ERROR); |
0f113f3e MC |
121 | goto err; |
122 | } | |
123 | if ((buf = OPENSSL_malloc(buflen)) == NULL) { | |
77470e98 | 124 | ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY, ERR_R_MALLOC_FAILURE); |
0f113f3e MC |
125 | goto err; |
126 | } | |
127 | ||
128 | memset(buf, 0, buflen - len); | |
129 | if (len != (size_t)BN_bn2bin(x, buf + buflen - len)) { | |
77470e98 | 130 | ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY, ERR_R_BN_LIB); |
0f113f3e MC |
131 | goto err; |
132 | } | |
133 | ||
e2285d87 DSH |
134 | *pout = buf; |
135 | *poutlen = buflen; | |
136 | buf = NULL; | |
137 | ||
138 | ret = 1; | |
0f113f3e MC |
139 | |
140 | err: | |
8fdc3734 | 141 | EC_POINT_free(tmp); |
0f113f3e MC |
142 | if (ctx) |
143 | BN_CTX_end(ctx); | |
23a1d5e9 | 144 | BN_CTX_free(ctx); |
b548a1f1 | 145 | OPENSSL_free(buf); |
e2285d87 | 146 | return ret; |
0f113f3e | 147 | } |