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
|
/*
* pbkdf2.c
* --------
* PBKDF2 (RFC 2898) on top of HAL interface to Cryptech hash cores.
*
* Authors: Rob Austein
* Copyright (c) 2015, NORDUnet A/S
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
* - Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* - Neither the name of the NORDUnet nor the names of its contributors may
* be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
* PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
* TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <string.h>
#include <stdint.h>
#include "hal.h"
#include "hal_internal.h"
/*
* Utility to encapsulate the HMAC operations. May need refactoring
* if and when we get clever about reusing HMAC state for speed.
*/
static hal_error_t do_hmac(hal_core_t *core,
const hal_hash_descriptor_t * const d,
const uint8_t * const pw, const size_t pw_len,
const uint8_t * const data, const size_t data_len,
const uint32_t block,
uint8_t * mac, const size_t mac_len)
{
hal_assert(d != NULL && pw != NULL && data != NULL && mac != NULL);
uint8_t sb[d->hmac_state_length];
hal_hmac_state_t *s;
hal_error_t err;
if ((err = hal_hmac_initialize(core, d, &s, sb, sizeof(sb), pw, pw_len)) != HAL_OK)
return err;
if ((err = hal_hmac_update(s, data, data_len)) != HAL_OK)
return err;
if (block > 0) {
uint8_t b[4] = { (block >> 24) & 0xFF, (block >> 16) & 0xFF, (block >> 8) & 0xFF, (block >> 0) & 0xFF };
if ((err = hal_hmac_update(s, b, sizeof(b))) != HAL_OK)
return err;
}
return hal_hmac_finalize(s, mac, mac_len);
}
/*
* Derive a key from a passphrase using the PBKDF2 algorithm.
*/
hal_error_t hal_pbkdf2(hal_core_t *core,
const hal_hash_descriptor_t * const descriptor,
const uint8_t * const password, const size_t password_length,
const uint8_t * const salt, const size_t salt_length,
uint8_t * derived_key, size_t derived_key_length,
unsigned iterations_desired)
{
uint8_t result[HAL_MAX_HASH_DIGEST_LENGTH], mac[HAL_MAX_HASH_DIGEST_LENGTH];
uint8_t statebuf[1024];
unsigned iteration;
hal_error_t err;
uint32_t block;
if (descriptor == NULL || password == NULL || salt == NULL ||
derived_key == NULL || derived_key_length == 0 ||
iterations_desired == 0)
return HAL_ERROR_BAD_ARGUMENTS;
hal_assert(sizeof(statebuf) >= descriptor->hmac_state_length);
hal_assert(sizeof(result) >= descriptor->digest_length);
hal_assert(sizeof(mac) >= descriptor->digest_length);
/* Output length check per RFC 2989 5.2. */
if ((uint64_t) derived_key_length > ((uint64_t) 0xFFFFFFFF) * descriptor->block_length)
return HAL_ERROR_UNSUPPORTED_KEY;
memset(result, 0, sizeof(result));
memset(mac, 0, sizeof(mac));
/*
* We probably should check here to see whether the password is
* longer than the HMAC block size, and, if so, we should hash the
* password here to avoid having recomputing that every time through
* the loops below. There are other optimizations we'd like to
* make, but this one doesn't require being able to save and restore
* the hash state.
*/
/*
* Generate output blocks until we reach the requested length.
*/
for (block = 1; ; block++) {
/*
* Initial HMAC is of the salt concatenated with the block count.
* This seeds the result, and constitutes iteration one.
*/
if ((err = do_hmac(core, descriptor, password, password_length,
salt, salt_length, block, mac, sizeof(mac))) != HAL_OK)
return err;
memcpy(result, mac, descriptor->digest_length);
/*
* Now iterate however many times the caller requested, XORing the
* HMAC back into the result on each iteration.
*/
for (iteration = 2; iteration <= iterations_desired; iteration++) {
hal_task_yield_maybe();
if ((err = do_hmac(core, descriptor, password, password_length,
mac, descriptor->digest_length,
0, mac, sizeof(mac))) != HAL_OK)
return err;
for (size_t i = 0; i < descriptor->digest_length; i++)
result[i] ^= mac[i];
}
/*
* Save result block, then exit or loop for another block.
*/
if (derived_key_length > descriptor->digest_length) {
memcpy(derived_key, result, descriptor->digest_length);
derived_key += descriptor->digest_length;
derived_key_length -= descriptor->digest_length;
}
else {
memcpy(derived_key, result, derived_key_length);
return HAL_OK;
}
}
}
/*
* Local variables:
* indent-tabs-mode: nil
* End:
*/
|
