1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
|
/*
* Copyright (C) 2008-2010 Tobias Brunner
* Copyright (C) 2008 Martin Willi
* Hochschule fuer Technik Rapperswil
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version. See <http://www.fsf.org/copyleft/gpl.txt>.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* for more details.
*/
#include <openssl/opensslconf.h>
#ifndef OPENSSL_NO_DH
#include <openssl/dh.h>
#include "openssl_diffie_hellman.h"
#include <utils/debug.h>
typedef struct private_openssl_diffie_hellman_t private_openssl_diffie_hellman_t;
/**
* Private data of an openssl_diffie_hellman_t object.
*/
struct private_openssl_diffie_hellman_t {
/**
* Public openssl_diffie_hellman_t interface.
*/
openssl_diffie_hellman_t public;
/**
* Diffie Hellman group number.
*/
diffie_hellman_group_t group;
/**
* Diffie Hellman object
*/
DH *dh;
/**
* Other public value
*/
BIGNUM *pub_key;
/**
* Shared secret
*/
chunk_t shared_secret;
/**
* True if shared secret is computed
*/
bool computed;
};
METHOD(diffie_hellman_t, get_my_public_value, bool,
private_openssl_diffie_hellman_t *this, chunk_t *value)
{
*value = chunk_alloc(DH_size(this->dh));
memset(value->ptr, 0, value->len);
BN_bn2bin(this->dh->pub_key,
value->ptr + value->len - BN_num_bytes(this->dh->pub_key));
return TRUE;
}
METHOD(diffie_hellman_t, get_shared_secret, bool,
private_openssl_diffie_hellman_t *this, chunk_t *secret)
{
if (!this->computed)
{
return FALSE;
}
/* shared secret should requires a len according the DH group */
*secret = chunk_alloc(DH_size(this->dh));
memset(secret->ptr, 0, secret->len);
memcpy(secret->ptr + secret->len - this->shared_secret.len,
this->shared_secret.ptr, this->shared_secret.len);
return TRUE;
}
METHOD(diffie_hellman_t, set_other_public_value, bool,
private_openssl_diffie_hellman_t *this, chunk_t value)
{
int len;
if (!diffie_hellman_verify_value(this->group, value))
{
return FALSE;
}
BN_bin2bn(value.ptr, value.len, this->pub_key);
chunk_clear(&this->shared_secret);
this->shared_secret.ptr = malloc(DH_size(this->dh));
memset(this->shared_secret.ptr, 0xFF, this->shared_secret.len);
len = DH_compute_key(this->shared_secret.ptr, this->pub_key, this->dh);
if (len < 0)
{
DBG1(DBG_LIB, "DH shared secret computation failed");
return FALSE;
}
this->shared_secret.len = len;
this->computed = TRUE;
return TRUE;
}
METHOD(diffie_hellman_t, get_dh_group, diffie_hellman_group_t,
private_openssl_diffie_hellman_t *this)
{
return this->group;
}
/**
* Lookup the modulus in modulo table
*/
static status_t set_modulus(private_openssl_diffie_hellman_t *this)
{
diffie_hellman_params_t *params = diffie_hellman_get_params(this->group);
if (!params)
{
return NOT_FOUND;
}
this->dh->p = BN_bin2bn(params->prime.ptr, params->prime.len, NULL);
this->dh->g = BN_bin2bn(params->generator.ptr, params->generator.len, NULL);
if (params->exp_len != params->prime.len)
{
this->dh->length = params->exp_len * 8;
}
return SUCCESS;
}
METHOD(diffie_hellman_t, destroy, void,
private_openssl_diffie_hellman_t *this)
{
BN_clear_free(this->pub_key);
DH_free(this->dh);
chunk_clear(&this->shared_secret);
free(this);
}
/*
* Described in header.
*/
openssl_diffie_hellman_t *openssl_diffie_hellman_create(
diffie_hellman_group_t group, chunk_t g, chunk_t p)
{
private_openssl_diffie_hellman_t *this;
INIT(this,
.public = {
.dh = {
.get_shared_secret = _get_shared_secret,
.set_other_public_value = _set_other_public_value,
.get_my_public_value = _get_my_public_value,
.get_dh_group = _get_dh_group,
.destroy = _destroy,
},
},
);
this->dh = DH_new();
if (!this->dh)
{
free(this);
return NULL;
}
this->group = group;
this->computed = FALSE;
this->pub_key = BN_new();
this->shared_secret = chunk_empty;
if (group == MODP_CUSTOM)
{
this->dh->p = BN_bin2bn(p.ptr, p.len, NULL);
this->dh->g = BN_bin2bn(g.ptr, g.len, NULL);
}
else
{
/* find a modulus according to group */
if (set_modulus(this) != SUCCESS)
{
destroy(this);
return NULL;
}
}
/* generate my public and private values */
if (!DH_generate_key(this->dh))
{
destroy(this);
return NULL;
}
DBG2(DBG_LIB, "size of DH secret exponent: %d bits",
BN_num_bits(this->dh->priv_key));
return &this->public;
}
#endif /* OPENSSL_NO_DH */
|
