2 This file is part of GNUnet.
3 (C) 2001, 2002, 2003, 2004, 2005, 2006 Christian Grothoff (and other contributing authors)
5 GNUnet is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published
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11 WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 General Public License for more details.
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23 * @file util/crypto_random.c
24 * @brief functions to gather random numbers
25 * @author Christian Grothoff
28 #include "gnunet_common.h"
29 #include "gnunet_crypto_lib.h"
33 * @return a random value in the interval [0,i[.
36 GNUNET_CRYPTO_random_u32 (enum GNUNET_CRYPTO_Quality mode, unsigned int i)
38 #ifdef gcry_fast_random_poll
39 static unsigned int invokeCount;
43 GNUNET_assert (i > 0);
45 if (mode == GNUNET_CRYPTO_QUALITY_STRONG)
47 /* see http://lists.gnupg.org/pipermail/gcrypt-devel/2004-May/000613.html */
48 #ifdef gcry_fast_random_poll
49 if ((invokeCount++ % 256) == 0)
50 gcry_fast_random_poll ();
52 ret = rand (); /* in case gcry_randomize fails,
53 we at least get a pseudo-
54 random number this way */
55 gcry_randomize ((unsigned char *) &ret,
56 sizeof (unsigned int), GCRY_STRONG_RANDOM);
61 ret = i * ((double) RANDOM () / RAND_MAX);
70 * Get an array with a random permutation of the
72 * @param mode GNUNET_RANDOM_QUALITY_STRONG if the strong (but expensive)
73 * PRNG should be used, GNUNET_RANDOM_QUALITY_WEAK otherwise
74 * @param n the size of the array
75 * @return the permutation array (allocated from heap)
78 GNUNET_CRYPTO_random_permute (enum GNUNET_CRYPTO_Quality mode, unsigned int n)
85 GNUNET_assert (n > 0);
86 ret = GNUNET_malloc (n * sizeof (int));
87 for (i = 0; i < n; i++)
89 for (i = 0; i < n; i++)
91 x = GNUNET_CRYPTO_random_u32 (mode, n);
100 * Random on unsigned 64-bit values.
103 GNUNET_CRYPTO_random_u64 (enum GNUNET_CRYPTO_Quality mode,
104 unsigned long long u)
106 unsigned long long ret;
108 GNUNET_assert (u > 0);
109 if (mode == GNUNET_CRYPTO_QUALITY_STRONG)
111 gcry_randomize ((unsigned char *) &ret,
112 sizeof (unsigned long long), GCRY_STRONG_RANDOM);
117 ret = u * ((double) RANDOM () / RAND_MAX);
125 * This function should only be called in testcases
126 * where strong entropy gathering is not desired
127 * (for example, for hostkey generation).
130 GNUNET_CRYPTO_random_disable_entropy_gathering ()
132 gcry_control (GCRYCTL_ENABLE_QUICK_RANDOM, 0);
136 /* end of crypto_random.c */