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
|
/*
* Copyright (c) 1999,2000,2004 Damien Miller <djm@mindrot.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"
#include <sys/types.h>
#include <string.h>
#include <stdlib.h>
#include <stdarg.h>
#include "log.h"
#ifndef HAVE_ARC4RANDOM
#include <openssl/rand.h>
#include <openssl/rc4.h>
#include <openssl/err.h>
/* Size of key to use */
#define SEED_SIZE 20
/* Number of bytes to reseed after */
#define REKEY_BYTES (1 << 24)
static int rc4_ready = 0;
static RC4_KEY rc4;
unsigned int
arc4random(void)
{
unsigned int r = 0;
static int first_time = 1;
if (rc4_ready <= 0) {
if (first_time)
seed_rng();
first_time = 0;
arc4random_stir();
}
RC4(&rc4, sizeof(r), (unsigned char *)&r, (unsigned char *)&r);
rc4_ready -= sizeof(r);
return(r);
}
void
arc4random_stir(void)
{
unsigned char rand_buf[SEED_SIZE];
int i;
memset(&rc4, 0, sizeof(rc4));
if (RAND_bytes(rand_buf, sizeof(rand_buf)) <= 0)
fatal("Couldn't obtain random bytes (error %ld)",
ERR_get_error());
RC4_set_key(&rc4, sizeof(rand_buf), rand_buf);
/*
* Discard early keystream, as per recommendations in:
* http://www.wisdom.weizmann.ac.il/~itsik/RC4/Papers/Rc4_ksa.ps
*/
for(i = 0; i <= 256; i += sizeof(rand_buf))
RC4(&rc4, sizeof(rand_buf), rand_buf, rand_buf);
memset(rand_buf, 0, sizeof(rand_buf));
rc4_ready = REKEY_BYTES;
}
#endif /* !HAVE_ARC4RANDOM */
#ifndef HAVE_ARC4RANDOM_BUF
void
arc4random_buf(void *_buf, size_t n)
{
size_t i;
u_int32_t r = 0;
char *buf = (char *)_buf;
for (i = 0; i < n; i++) {
if (i % 4 == 0)
r = arc4random();
buf[i] = r & 0xff;
r >>= 8;
}
i = r = 0;
}
#endif /* !HAVE_ARC4RANDOM_BUF */
#ifndef HAVE_ARC4RANDOM_UNIFORM
/*
* Calculate a uniformly distributed random number less than upper_bound
* avoiding "modulo bias".
*
* Uniformity is achieved by generating new random numbers until the one
* returned is outside the range [0, 2**32 % upper_bound). This
* guarantees the selected random number will be inside
* [2**32 % upper_bound, 2**32) which maps back to [0, upper_bound)
* after reduction modulo upper_bound.
*/
u_int32_t
arc4random_uniform(u_int32_t upper_bound)
{
u_int32_t r, min;
if (upper_bound < 2)
return 0;
#if (ULONG_MAX > 0xffffffffUL)
min = 0x100000000UL % upper_bound;
#else
/* Calculate (2**32 % upper_bound) avoiding 64-bit math */
if (upper_bound > 0x80000000)
min = 1 + ~upper_bound; /* 2**32 - upper_bound */
else {
/* (2**32 - (x * 2)) % x == 2**32 % x when x <= 2**31 */
min = ((0xffffffff - (upper_bound * 2)) + 1) % upper_bound;
}
#endif
/*
* This could theoretically loop forever but each retry has
* p > 0.5 (worst case, usually far better) of selecting a
* number inside the range we need, so it should rarely need
* to re-roll.
*/
for (;;) {
r = arc4random();
if (r >= min)
break;
}
return r % upper_bound;
}
#endif /* !HAVE_ARC4RANDOM_UNIFORM */
|
