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3c0ef626 | 1 | /* |
416fd2a8 | 2 | * Copyright (c) 1999,2000,2004 Damien Miller <djm@mindrot.org> |
3c0ef626 | 3 | * |
416fd2a8 | 4 | * Permission to use, copy, modify, and distribute this software for any |
5 | * purpose with or without fee is hereby granted, provided that the above | |
6 | * copyright notice and this permission notice appear in all copies. | |
3c0ef626 | 7 | * |
416fd2a8 | 8 | * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES |
9 | * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF | |
10 | * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR | |
11 | * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES | |
12 | * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN | |
13 | * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF | |
14 | * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. | |
3c0ef626 | 15 | */ |
16 | ||
17 | #include "includes.h" | |
18 | #include "log.h" | |
19 | ||
20 | RCSID("$Id$"); | |
21 | ||
22 | #ifndef HAVE_ARC4RANDOM | |
23 | ||
24 | #include <openssl/rand.h> | |
25 | #include <openssl/rc4.h> | |
26 | #include <openssl/err.h> | |
27 | ||
28 | /* Size of key to use */ | |
29 | #define SEED_SIZE 20 | |
30 | ||
31 | /* Number of bytes to reseed after */ | |
32 | #define REKEY_BYTES (1 << 24) | |
33 | ||
34 | static int rc4_ready = 0; | |
35 | static RC4_KEY rc4; | |
36 | ||
34fee935 | 37 | unsigned int |
38 | arc4random(void) | |
3c0ef626 | 39 | { |
40 | unsigned int r = 0; | |
41 | static int first_time = 1; | |
42 | ||
43 | if (rc4_ready <= 0) { | |
2980ea68 | 44 | if (first_time) |
3c0ef626 | 45 | seed_rng(); |
46 | first_time = 0; | |
47 | arc4random_stir(); | |
48 | } | |
49 | ||
50 | RC4(&rc4, sizeof(r), (unsigned char *)&r, (unsigned char *)&r); | |
51 | ||
52 | rc4_ready -= sizeof(r); | |
53 | ||
54 | return(r); | |
55 | } | |
56 | ||
34fee935 | 57 | void |
58 | arc4random_stir(void) | |
3c0ef626 | 59 | { |
60 | unsigned char rand_buf[SEED_SIZE]; | |
1b56ff3d | 61 | int i; |
3c0ef626 | 62 | |
63 | memset(&rc4, 0, sizeof(rc4)); | |
1c14df9e | 64 | if (RAND_bytes(rand_buf, sizeof(rand_buf)) <= 0) |
3c0ef626 | 65 | fatal("Couldn't obtain random bytes (error %ld)", |
66 | ERR_get_error()); | |
67 | RC4_set_key(&rc4, sizeof(rand_buf), rand_buf); | |
1b56ff3d | 68 | |
69 | /* | |
70 | * Discard early keystream, as per recommendations in: | |
71 | * http://www.wisdom.weizmann.ac.il/~itsik/RC4/Papers/Rc4_ksa.ps | |
72 | */ | |
73 | for(i = 0; i <= 256; i += sizeof(rand_buf)) | |
74 | RC4(&rc4, sizeof(rand_buf), rand_buf, rand_buf); | |
75 | ||
3c0ef626 | 76 | memset(rand_buf, 0, sizeof(rand_buf)); |
77 | ||
78 | rc4_ready = REKEY_BYTES; | |
79 | } | |
80 | #endif /* !HAVE_ARC4RANDOM */ |