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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); | |
77470e98 DSH |
41 | return -1; |
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); | |
69 | ||
70 | priv_key = EC_KEY_get0_private_key(ecdh); | |
71 | if (priv_key == NULL) { | |
77470e98 | 72 | ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY, EC_R_NO_PRIVATE_VALUE); |
0f113f3e MC |
73 | goto err; |
74 | } | |
75 | ||
76 | group = EC_KEY_get0_group(ecdh); | |
77 | ||
78 | if (EC_KEY_get_flags(ecdh) & EC_FLAG_COFACTOR_ECDH) { | |
a773b52a | 79 | if (!EC_GROUP_get_cofactor(group, x, NULL) || |
0f113f3e | 80 | !BN_mul(x, x, priv_key, ctx)) { |
77470e98 | 81 | ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY, ERR_R_MALLOC_FAILURE); |
0f113f3e MC |
82 | goto err; |
83 | } | |
84 | priv_key = x; | |
85 | } | |
86 | ||
87 | if ((tmp = EC_POINT_new(group)) == NULL) { | |
77470e98 | 88 | ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY, ERR_R_MALLOC_FAILURE); |
0f113f3e MC |
89 | goto err; |
90 | } | |
91 | ||
92 | if (!EC_POINT_mul(group, tmp, NULL, pub_key, priv_key, ctx)) { | |
77470e98 | 93 | ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY, EC_R_POINT_ARITHMETIC_FAILURE); |
0f113f3e MC |
94 | goto err; |
95 | } | |
96 | ||
97 | if (EC_METHOD_get_field_type(EC_GROUP_method_of(group)) == | |
98 | NID_X9_62_prime_field) { | |
99 | if (!EC_POINT_get_affine_coordinates_GFp(group, tmp, x, y, ctx)) { | |
77470e98 | 100 | ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY, EC_R_POINT_ARITHMETIC_FAILURE); |
0f113f3e MC |
101 | goto err; |
102 | } | |
103 | } | |
b3310161 | 104 | #ifndef OPENSSL_NO_EC2M |
0f113f3e MC |
105 | else { |
106 | if (!EC_POINT_get_affine_coordinates_GF2m(group, tmp, x, y, ctx)) { | |
77470e98 | 107 | ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY, EC_R_POINT_ARITHMETIC_FAILURE); |
0f113f3e MC |
108 | goto err; |
109 | } | |
110 | } | |
b3310161 | 111 | #endif |
e172d60d | 112 | |
0f113f3e MC |
113 | buflen = (EC_GROUP_get_degree(group) + 7) / 8; |
114 | len = BN_num_bytes(x); | |
115 | if (len > buflen) { | |
77470e98 | 116 | ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY, ERR_R_INTERNAL_ERROR); |
0f113f3e MC |
117 | goto err; |
118 | } | |
119 | if ((buf = OPENSSL_malloc(buflen)) == NULL) { | |
77470e98 | 120 | ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY, ERR_R_MALLOC_FAILURE); |
0f113f3e MC |
121 | goto err; |
122 | } | |
123 | ||
124 | memset(buf, 0, buflen - len); | |
125 | if (len != (size_t)BN_bn2bin(x, buf + buflen - len)) { | |
77470e98 | 126 | ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY, ERR_R_BN_LIB); |
0f113f3e MC |
127 | goto err; |
128 | } | |
129 | ||
e2285d87 DSH |
130 | *pout = buf; |
131 | *poutlen = buflen; | |
132 | buf = NULL; | |
133 | ||
134 | ret = 1; | |
0f113f3e MC |
135 | |
136 | err: | |
8fdc3734 | 137 | EC_POINT_free(tmp); |
0f113f3e MC |
138 | if (ctx) |
139 | BN_CTX_end(ctx); | |
23a1d5e9 | 140 | BN_CTX_free(ctx); |
b548a1f1 | 141 | OPENSSL_free(buf); |
e2285d87 | 142 | return ret; |
0f113f3e | 143 | } |