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
7 by the Free Software Foundation; either version 2, or (at your
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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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17 Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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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 * Produce a random value.
35 * @param mode desired quality of the random number
36 * @param i the upper limit (exclusive) for the random number
37 * @return a random value in the interval [0,i[.
40 GNUNET_CRYPTO_random_u32 (enum GNUNET_CRYPTO_Quality mode, uint32_t i)
42 #ifdef gcry_fast_random_poll
43 static unsigned int invokeCount;
47 GNUNET_assert (i > 0);
49 if (mode == GNUNET_CRYPTO_QUALITY_STRONG)
51 /* see http://lists.gnupg.org/pipermail/gcrypt-devel/2004-May/000613.html */
52 #ifdef gcry_fast_random_poll
53 if ((invokeCount++ % 256) == 0)
54 gcry_fast_random_poll ();
56 gcry_randomize ((unsigned char *) &ret,
57 sizeof (uint32_t), GCRY_STRONG_RANDOM);
62 ret = i * ((double) RANDOM () / RAND_MAX);
71 * Get an array with a random permutation of the
73 * @param mode GNUNET_RANDOM_QUALITY_STRONG if the strong (but expensive)
74 * PRNG should be used, GNUNET_RANDOM_QUALITY_WEAK otherwise
75 * @param n the size of the array
76 * @return the permutation array (allocated from heap)
79 GNUNET_CRYPTO_random_permute (enum GNUNET_CRYPTO_Quality mode, unsigned int n)
86 GNUNET_assert (n > 0);
87 ret = GNUNET_malloc (n * sizeof (unsigned int));
88 for (i = 0; i < n; i++)
90 for (i = 0; i < n; i++)
92 x = GNUNET_CRYPTO_random_u32 (mode, n);
101 * Random on unsigned 64-bit values.
104 * @param mode desired quality of the random number
105 * @param max value returned will be in range [0,max) (exclusive)
106 * @return random 64-bit number
109 GNUNET_CRYPTO_random_u64 (enum GNUNET_CRYPTO_Quality mode, uint64_t max)
113 GNUNET_assert (max > 0);
114 if (mode == GNUNET_CRYPTO_QUALITY_STRONG)
116 gcry_randomize ((unsigned char *) &ret,
117 sizeof (uint64_t), GCRY_STRONG_RANDOM);
122 ret = max * ((double) RANDOM () / RAND_MAX);
130 * This function should only be called in testcases
131 * where strong entropy gathering is not desired
132 * (for example, for hostkey generation).
135 GNUNET_CRYPTO_random_disable_entropy_gathering ()
137 gcry_control (GCRYCTL_ENABLE_QUICK_RANDOM, 0);
143 void __attribute__ ((constructor)) GNUNET_util_random_init ()
145 SRANDOM (time (NULL));
148 /* end of crypto_random.c */