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Commit | Line | Data |
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4f22f405 | 1 | /* |
c4d3c19b | 2 | * Copyright 2002-2018 The OpenSSL Project Authors. All Rights Reserved. |
aa8f3d76 | 3 | * Copyright (c) 2002, Oracle and/or its affiliates. All rights reserved |
4f22f405 | 4 | * |
a7f182b7 | 5 | * Licensed under the Apache License 2.0 (the "License"). You may not use |
4f22f405 RS |
6 | * this file except in compliance with the License. You can obtain a copy |
7 | * in the file LICENSE in the source distribution or at | |
8 | * https://www.openssl.org/source/license.html | |
9 | */ | |
10 | ||
8b5bcef7 | 11 | #include <string.h> |
176f31dd BM |
12 | #include <limits.h> |
13 | ||
b39fc560 | 14 | #include "internal/cryptlib.h" |
10a66ad3 | 15 | |
e172d60d | 16 | #include <openssl/err.h> |
0f814687 | 17 | #include <openssl/bn.h> |
647b2238 DSH |
18 | #include <openssl/objects.h> |
19 | #include <openssl/ec.h> | |
706457b7 | 20 | #include "ec_local.h" |
e172d60d | 21 | |
e2285d87 DSH |
22 | int ossl_ecdh_compute_key(unsigned char **psec, size_t *pseclen, |
23 | const EC_POINT *pub_key, const EC_KEY *ecdh) | |
77470e98 | 24 | { |
9ff9bccc DSH |
25 | if (ecdh->group->meth->ecdh_compute_key == NULL) { |
26 | ECerr(EC_F_OSSL_ECDH_COMPUTE_KEY, EC_R_CURVE_DOES_NOT_SUPPORT_ECDH); | |
65ea288d | 27 | return 0; |
77470e98 DSH |
28 | } |
29 | ||
e2285d87 | 30 | return ecdh->group->meth->ecdh_compute_key(psec, pseclen, pub_key, ecdh); |
77470e98 DSH |
31 | } |
32 | ||
3a83462d MC |
33 | /*- |
34 | * This implementation is based on the following primitives in the IEEE 1363 standard: | |
e172d60d BM |
35 | * - ECKAS-DH1 |
36 | * - ECSVDP-DH | |
e172d60d | 37 | */ |
e2285d87 DSH |
38 | int ecdh_simple_compute_key(unsigned char **pout, size_t *poutlen, |
39 | const EC_POINT *pub_key, const EC_KEY *ecdh) | |
0f113f3e MC |
40 | { |
41 | BN_CTX *ctx; | |
42 | EC_POINT *tmp = NULL; | |
ddc1caac | 43 | BIGNUM *x = NULL; |
0f113f3e MC |
44 | const BIGNUM *priv_key; |
45 | const EC_GROUP *group; | |
e2285d87 | 46 | int ret = 0; |
0f113f3e MC |
47 | size_t buflen, len; |
48 | unsigned char *buf = NULL; | |
49 | ||
a9612d6c | 50 | if ((ctx = BN_CTX_new_ex(ecdh->libctx)) == NULL) |
0f113f3e MC |
51 | goto err; |
52 | BN_CTX_start(ctx); | |
53 | x = BN_CTX_get(ctx); | |
ddc1caac | 54 | if (x == NULL) { |
abea494c BE |
55 | ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY, ERR_R_MALLOC_FAILURE); |
56 | goto err; | |
57 | } | |
0f113f3e MC |
58 | |
59 | priv_key = EC_KEY_get0_private_key(ecdh); | |
60 | if (priv_key == NULL) { | |
7408f675 | 61 | ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY, EC_R_MISSING_PRIVATE_KEY); |
0f113f3e MC |
62 | goto err; |
63 | } | |
64 | ||
65 | group = EC_KEY_get0_group(ecdh); | |
66 | ||
67 | if (EC_KEY_get_flags(ecdh) & EC_FLAG_COFACTOR_ECDH) { | |
a773b52a | 68 | if (!EC_GROUP_get_cofactor(group, x, NULL) || |
0f113f3e | 69 | !BN_mul(x, x, priv_key, ctx)) { |
77470e98 | 70 | ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY, ERR_R_MALLOC_FAILURE); |
0f113f3e MC |
71 | goto err; |
72 | } | |
73 | priv_key = x; | |
74 | } | |
75 | ||
76 | if ((tmp = EC_POINT_new(group)) == NULL) { | |
77470e98 | 77 | ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY, ERR_R_MALLOC_FAILURE); |
0f113f3e MC |
78 | goto err; |
79 | } | |
80 | ||
81 | if (!EC_POINT_mul(group, tmp, NULL, pub_key, priv_key, ctx)) { | |
77470e98 | 82 | ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY, EC_R_POINT_ARITHMETIC_FAILURE); |
0f113f3e MC |
83 | goto err; |
84 | } | |
85 | ||
9cc570d4 MC |
86 | if (!EC_POINT_get_affine_coordinates(group, tmp, x, NULL, ctx)) { |
87 | ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY, EC_R_POINT_ARITHMETIC_FAILURE); | |
88 | goto err; | |
0f113f3e | 89 | } |
e172d60d | 90 | |
0f113f3e MC |
91 | buflen = (EC_GROUP_get_degree(group) + 7) / 8; |
92 | len = BN_num_bytes(x); | |
93 | if (len > buflen) { | |
77470e98 | 94 | ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY, ERR_R_INTERNAL_ERROR); |
0f113f3e MC |
95 | goto err; |
96 | } | |
97 | if ((buf = OPENSSL_malloc(buflen)) == NULL) { | |
77470e98 | 98 | ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY, ERR_R_MALLOC_FAILURE); |
0f113f3e MC |
99 | goto err; |
100 | } | |
101 | ||
102 | memset(buf, 0, buflen - len); | |
103 | if (len != (size_t)BN_bn2bin(x, buf + buflen - len)) { | |
77470e98 | 104 | ECerr(EC_F_ECDH_SIMPLE_COMPUTE_KEY, ERR_R_BN_LIB); |
0f113f3e MC |
105 | goto err; |
106 | } | |
107 | ||
e2285d87 DSH |
108 | *pout = buf; |
109 | *poutlen = buflen; | |
110 | buf = NULL; | |
111 | ||
112 | ret = 1; | |
0f113f3e MC |
113 | |
114 | err: | |
1ff2c992 | 115 | EC_POINT_clear_free(tmp); |
ce1415ed | 116 | BN_CTX_end(ctx); |
23a1d5e9 | 117 | BN_CTX_free(ctx); |
b548a1f1 | 118 | OPENSSL_free(buf); |
e2285d87 | 119 | return ret; |
0f113f3e | 120 | } |