Mercurial > dropbear

comparison libtomcrypt/src/prngs/rng_make_prng.c @ 285:1b9e69c058d2

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3) to branch 'au.asn.ucc.matt.dropbear' (head fdf4a7a3b97ae5046139915de7e40399cceb2c01)
author Matt Johnston <matt@ucc.asn.au>
date Wed, 08 Mar 2006 13:23:58 +0000
parents
children 0cbe8f6dbf9e
comparison
equal deleted inserted replaced
281:997e6f7dc01e 285:1b9e69c058d2
1 /* LibTomCrypt, modular cryptographic library -- Tom St Denis
2 *
3 * LibTomCrypt is a library that provides various cryptographic
4 * algorithms in a highly modular and flexible manner.
5 *
6 * The library is free for all purposes without any express
7 * guarantee it works.
8 *
9 * Tom St Denis, [email protected], http://libtomcrypt.org
10 */
11 #include "tomcrypt.h"
12
13 /**
14 @file rng_make_prng.c
15 portable way to get secure random bits to feed a PRNG (Tom St Denis)
16 */
17
18 /**
19 Create a PRNG from a RNG
20 @param bits Number of bits of entropy desired (64 ... 1024)
21 @param wprng Index of which PRNG to setup
22 @param prng [out] PRNG state to initialize
23 @param callback A pointer to a void function for when the RNG is slow, this can be NULL
24 @return CRYPT_OK if successful
25 */
26 int rng_make_prng(int bits, int wprng, prng_state *prng,
27 void (*callback)(void))
28 {
29 unsigned char buf[256];
30 int err;
31
32 LTC_ARGCHK(prng != NULL);
33
34 /* check parameter */
35 if ((err = prng_is_valid(wprng)) != CRYPT_OK) {
36 return err;
37 }
38
39 if (bits < 64 || bits > 1024) {
40 return CRYPT_INVALID_PRNGSIZE;
41 }
42
43 if ((err = prng_descriptor[wprng].start(prng)) != CRYPT_OK) {
44 return err;
45 }
46
47 bits = ((bits/8)+((bits&7)!=0?1:0)) * 2;
48 if (rng_get_bytes(buf, (unsigned long)bits, callback) != (unsigned long)bits) {
49 return CRYPT_ERROR_READPRNG;
50 }
51
52 if ((err = prng_descriptor[wprng].add_entropy(buf, (unsigned long)bits, prng)) != CRYPT_OK) {
53 return err;
54 }
55
56 if ((err = prng_descriptor[wprng].ready(prng)) != CRYPT_OK) {
57 return err;
58 }
59
60 #ifdef LTC_CLEAN_STACK
61 zeromem(buf, sizeof(buf));
62 #endif
63 return CRYPT_OK;
64 }
65
66
67 /* $Source: /cvs/libtom/libtomcrypt/src/prngs/rng_make_prng.c,v $ */
68 /* $Revision: 1.3 $ */
69 /* $Date: 2005/05/05 14:35:59 $ */