2 This file is part of GNUnet.
3 (C) 2001, 2002, 2003, 2004, 2005, 2006 Christian Grothoff (and other contributing authors)
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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"
30 #include "gnunet_os_lib.h"
34 * Create a cryptographically weak pseudo-random number in the interval of 0 to 1.
36 * @return number between 0 and 1.
41 return ((double) RANDOM () / RAND_MAX);
46 * Produce a random value.
48 * @param mode desired quality of the random number
49 * @param i the upper limit (exclusive) for the random number
50 * @return a random value in the interval [0,i[.
53 GNUNET_CRYPTO_random_u32 (enum GNUNET_CRYPTO_Quality mode, uint32_t i)
55 #ifdef gcry_fast_random_poll
56 static unsigned int invokeCount;
61 GNUNET_assert (i > 0);
63 if (mode == GNUNET_CRYPTO_QUALITY_STRONG)
65 /* see http://lists.gnupg.org/pipermail/gcrypt-devel/2004-May/000613.html */
66 #ifdef gcry_fast_random_poll
67 if ((invokeCount++ % 256) == 0)
68 gcry_fast_random_poll ();
70 ul = UINT32_MAX - (UINT32_MAX % i);
73 gcry_randomize ((unsigned char *) &ret,
74 sizeof (uint32_t), GCRY_STRONG_RANDOM);
81 ret = i * weak_random ();
90 * Get an array with a random permutation of the
92 * @param mode GNUNET_RANDOM_QUALITY_STRONG if the strong (but expensive)
93 * PRNG should be used, GNUNET_RANDOM_QUALITY_WEAK otherwise
94 * @param n the size of the array
95 * @return the permutation array (allocated from heap)
98 GNUNET_CRYPTO_random_permute (enum GNUNET_CRYPTO_Quality mode, unsigned int n)
105 GNUNET_assert (n > 0);
106 ret = GNUNET_malloc (n * sizeof (unsigned int));
107 for (i = 0; i < n; i++)
109 for (i = n - 1; i > 0; i--)
111 x = GNUNET_CRYPTO_random_u32 (mode, i+1);
120 * Random on unsigned 64-bit values.
123 * @param mode desired quality of the random number
124 * @param max value returned will be in range [0,max) (exclusive)
125 * @return random 64-bit number
128 GNUNET_CRYPTO_random_u64 (enum GNUNET_CRYPTO_Quality mode, uint64_t max)
133 GNUNET_assert (max > 0);
134 if (mode == GNUNET_CRYPTO_QUALITY_STRONG)
136 ul = UINT64_MAX - (UINT64_MAX % max);
139 gcry_randomize ((unsigned char *) &ret,
140 sizeof (uint64_t), GCRY_STRONG_RANDOM);
147 ret = max * weak_random ();
155 * This function should only be called in testcases
156 * where strong entropy gathering is not desired
157 * (for example, for hostkey generation).
160 GNUNET_CRYPTO_random_disable_entropy_gathering ()
162 gcry_control (GCRYCTL_ENABLE_QUICK_RANDOM, 0);
167 * Process ID of the "find" process that we use for
170 static pid_t genproc;
173 * Function called by libgcrypt whenever we are
174 * blocked gathering entropy.
177 entropy_generator (void *cls,
178 const char *what, int printchar, int current, int total)
181 enum GNUNET_OS_ProcessStatusType type;
184 if (0 != strcmp (what, "need_entropy"))
186 if (current == total)
190 if (0 != PLIBC_KILL (genproc, SIGTERM))
191 GNUNET_log_strerror (GNUNET_ERROR_TYPE_ERROR, "kill");
192 GNUNET_break (GNUNET_OK == GNUNET_OS_process_wait (genproc));
199 ret = GNUNET_OS_process_status (genproc, &type, &code);
200 if (ret == GNUNET_NO)
201 return; /* still running */
202 if (ret == GNUNET_SYSERR)
207 if (0 != PLIBC_KILL (genproc, SIGTERM))
208 GNUNET_log_strerror (GNUNET_ERROR_TYPE_ERROR, "kill");
209 GNUNET_break (GNUNET_OK == GNUNET_OS_process_wait (genproc));
212 GNUNET_log (GNUNET_ERROR_TYPE_INFO,
213 _("Starting `%s' process to generate entropy\n"), "find");
214 genproc = GNUNET_OS_start_process (NULL, NULL, "sh",
217 "exec find / -mount -type f -exec cp {} /dev/null \\; 2>/dev/null",
227 PLIBC_KILL (genproc, SIGKILL);
233 void __attribute__ ((constructor)) GNUNET_CRYPTO_random_init ()
235 SRANDOM (time (NULL));
236 gcry_control (GCRYCTL_DISABLE_SECMEM, 0);
237 if (!gcry_check_version (GCRYPT_VERSION))
241 ("libgcrypt has not the expected version (version %s is required).\n"),
245 #ifdef gcry_fast_random_poll
246 gcry_fast_random_poll ();
248 gcry_set_progress_handler (&entropy_generator, NULL);
253 void __attribute__ ((destructor)) GNUNET_CRYPTO_random_fini ()
255 gcry_set_progress_handler (NULL, NULL);
260 /* end of crypto_random.c */