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
|
/* $OpenBSD: bcrypt_pbkdf.c,v 1.13 2015/01/12 03:20:04 tedu Exp $ */
/*
* Copyright (c) 2013 Ted Unangst <tedu@openbsd.org>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include "includes.h"
#ifndef HAVE_BCRYPT_PBKDF
#include <sys/types.h>
#include <sys/param.h>
#ifdef HAVE_STDLIB_H
# include <stdlib.h>
#endif
#include <string.h>
#ifdef HAVE_BLF_H
# include <blf.h>
#endif
#include "crypto_api.h"
#ifdef SHA512_DIGEST_LENGTH
# undef SHA512_DIGEST_LENGTH
#endif
#define SHA512_DIGEST_LENGTH crypto_hash_sha512_BYTES
#define MINIMUM(a,b) (((a) < (b)) ? (a) : (b))
/*
* pkcs #5 pbkdf2 implementation using the "bcrypt" hash
*
* The bcrypt hash function is derived from the bcrypt password hashing
* function with the following modifications:
* 1. The input password and salt are preprocessed with SHA512.
* 2. The output length is expanded to 256 bits.
* 3. Subsequently the magic string to be encrypted is lengthened and modifed
* to "OxychromaticBlowfishSwatDynamite"
* 4. The hash function is defined to perform 64 rounds of initial state
* expansion. (More rounds are performed by iterating the hash.)
*
* Note that this implementation pulls the SHA512 operations into the caller
* as a performance optimization.
*
* One modification from official pbkdf2. Instead of outputting key material
* linearly, we mix it. pbkdf2 has a known weakness where if one uses it to
* generate (e.g.) 512 bits of key material for use as two 256 bit keys, an
* attacker can merely run once through the outer loop, but the user
* always runs it twice. Shuffling output bytes requires computing the
* entirety of the key material to assemble any subkey. This is something a
* wise caller could do; we just do it for you.
*/
#define BCRYPT_WORDS 8
#define BCRYPT_HASHSIZE (BCRYPT_WORDS * 4)
static void
bcrypt_hash(u_int8_t *sha2pass, u_int8_t *sha2salt, u_int8_t *out)
{
blf_ctx state;
u_int8_t ciphertext[BCRYPT_HASHSIZE] =
"OxychromaticBlowfishSwatDynamite";
uint32_t cdata[BCRYPT_WORDS];
int i;
uint16_t j;
size_t shalen = SHA512_DIGEST_LENGTH;
/* key expansion */
Blowfish_initstate(&state);
Blowfish_expandstate(&state, sha2salt, shalen, sha2pass, shalen);
for (i = 0; i < 64; i++) {
Blowfish_expand0state(&state, sha2salt, shalen);
Blowfish_expand0state(&state, sha2pass, shalen);
}
/* encryption */
j = 0;
for (i = 0; i < BCRYPT_WORDS; i++)
cdata[i] = Blowfish_stream2word(ciphertext, sizeof(ciphertext),
&j);
for (i = 0; i < 64; i++)
blf_enc(&state, cdata, sizeof(cdata) / sizeof(uint64_t));
/* copy out */
for (i = 0; i < BCRYPT_WORDS; i++) {
out[4 * i + 3] = (cdata[i] >> 24) & 0xff;
out[4 * i + 2] = (cdata[i] >> 16) & 0xff;
out[4 * i + 1] = (cdata[i] >> 8) & 0xff;
out[4 * i + 0] = cdata[i] & 0xff;
}
/* zap */
explicit_bzero(ciphertext, sizeof(ciphertext));
explicit_bzero(cdata, sizeof(cdata));
explicit_bzero(&state, sizeof(state));
}
int
bcrypt_pbkdf(const char *pass, size_t passlen, const u_int8_t *salt, size_t saltlen,
u_int8_t *key, size_t keylen, unsigned int rounds)
{
u_int8_t sha2pass[SHA512_DIGEST_LENGTH];
u_int8_t sha2salt[SHA512_DIGEST_LENGTH];
u_int8_t out[BCRYPT_HASHSIZE];
u_int8_t tmpout[BCRYPT_HASHSIZE];
u_int8_t *countsalt;
size_t i, j, amt, stride;
uint32_t count;
size_t origkeylen = keylen;
/* nothing crazy */
if (rounds < 1)
return -1;
if (passlen == 0 || saltlen == 0 || keylen == 0 ||
keylen > sizeof(out) * sizeof(out) || saltlen > 1<<20)
return -1;
if ((countsalt = calloc(1, saltlen + 4)) == NULL)
return -1;
stride = (keylen + sizeof(out) - 1) / sizeof(out);
amt = (keylen + stride - 1) / stride;
memcpy(countsalt, salt, saltlen);
/* collapse password */
crypto_hash_sha512(sha2pass, pass, passlen);
/* generate key, sizeof(out) at a time */
for (count = 1; keylen > 0; count++) {
countsalt[saltlen + 0] = (count >> 24) & 0xff;
countsalt[saltlen + 1] = (count >> 16) & 0xff;
countsalt[saltlen + 2] = (count >> 8) & 0xff;
countsalt[saltlen + 3] = count & 0xff;
/* first round, salt is salt */
crypto_hash_sha512(sha2salt, countsalt, saltlen + 4);
bcrypt_hash(sha2pass, sha2salt, tmpout);
memcpy(out, tmpout, sizeof(out));
for (i = 1; i < rounds; i++) {
/* subsequent rounds, salt is previous output */
crypto_hash_sha512(sha2salt, tmpout, sizeof(tmpout));
bcrypt_hash(sha2pass, sha2salt, tmpout);
for (j = 0; j < sizeof(out); j++)
out[j] ^= tmpout[j];
}
/*
* pbkdf2 deviation: output the key material non-linearly.
*/
amt = MINIMUM(amt, keylen);
for (i = 0; i < amt; i++) {
size_t dest = i * stride + (count - 1);
if (dest >= origkeylen)
break;
key[dest] = out[i];
}
keylen -= i;
}
/* zap */
explicit_bzero(out, sizeof(out));
free(countsalt);
return 0;
}
#endif /* HAVE_BCRYPT_PBKDF */
|
