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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16 along with GNUnet; see the file COPYING. If not, write to the
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"
30 #include "gnunet_os_lib.h"
33 #define LOG(kind,...) GNUNET_log_from (kind, "util", __VA_ARGS__)
35 #define LOG_STRERROR(kind,syscall) GNUNET_log_from_strerror (kind, "util", syscall)
38 * Create a cryptographically weak pseudo-random number in the interval of 0 to 1.
40 * @return number between 0 and 1.
45 return ((double) RANDOM () / RAND_MAX);
50 * Produce a random value.
52 * @param mode desired quality of the random number
53 * @param i the upper limit (exclusive) for the random number
54 * @return a random value in the interval [0,i[.
57 GNUNET_CRYPTO_random_u32 (enum GNUNET_CRYPTO_Quality mode, uint32_t i)
59 #ifdef gcry_fast_random_poll
60 static unsigned int invokeCount;
65 GNUNET_assert (i > 0);
69 case GNUNET_CRYPTO_QUALITY_STRONG:
70 /* see http://lists.gnupg.org/pipermail/gcrypt-devel/2004-May/000613.html */
71 #ifdef gcry_fast_random_poll
72 if ((invokeCount++ % 256) == 0)
73 gcry_fast_random_poll ();
75 ul = UINT32_MAX - (UINT32_MAX % i);
78 gcry_randomize ((unsigned char *) &ret, sizeof (uint32_t),
83 case GNUNET_CRYPTO_QUALITY_NONCE:
84 ul = UINT32_MAX - (UINT32_MAX % i);
87 gcry_create_nonce (&ret, sizeof (ret));
91 case GNUNET_CRYPTO_QUALITY_WEAK:
92 ret = i * weak_random ();
104 * Get an array with a random permutation of the
106 * @param mode GNUNET_RANDOM_QUALITY_STRONG if the strong (but expensive)
107 * PRNG should be used, GNUNET_RANDOM_QUALITY_WEAK otherwise
108 * @param n the size of the array
109 * @return the permutation array (allocated from heap)
112 GNUNET_CRYPTO_random_permute (enum GNUNET_CRYPTO_Quality mode, unsigned int n)
119 GNUNET_assert (n > 0);
120 ret = GNUNET_malloc (n * sizeof (unsigned int));
121 for (i = 0; i < n; i++)
123 for (i = n - 1; i > 0; i--)
125 x = GNUNET_CRYPTO_random_u32 (mode, i + 1);
134 * Random on unsigned 64-bit values.
137 * @param mode desired quality of the random number
138 * @param max value returned will be in range [0,max) (exclusive)
139 * @return random 64-bit number
142 GNUNET_CRYPTO_random_u64 (enum GNUNET_CRYPTO_Quality mode, uint64_t max)
147 GNUNET_assert (max > 0);
150 case GNUNET_CRYPTO_QUALITY_STRONG:
151 ul = UINT64_MAX - (UINT64_MAX % max);
154 gcry_randomize ((unsigned char *) &ret, sizeof (uint64_t),
159 case GNUNET_CRYPTO_QUALITY_NONCE:
160 ul = UINT64_MAX - (UINT64_MAX % max);
163 gcry_create_nonce (&ret, sizeof (ret));
168 case GNUNET_CRYPTO_QUALITY_WEAK:
169 ret = max * weak_random ();
180 * This function should only be called in testcases
181 * where strong entropy gathering is not desired
182 * (for example, for hostkey generation).
185 GNUNET_CRYPTO_random_disable_entropy_gathering ()
187 gcry_control (GCRYCTL_ENABLE_QUICK_RANDOM, 0);
192 * Process ID of the "find" process that we use for
195 static struct GNUNET_OS_Process *genproc;
198 * Function called by libgcrypt whenever we are
199 * blocked gathering entropy.
202 entropy_generator (void *cls, const char *what, int printchar, int current,
206 enum GNUNET_OS_ProcessStatusType type;
209 if (0 != strcmp (what, "need_entropy"))
211 if (current == total)
215 if (0 != GNUNET_OS_process_kill (genproc, SIGTERM))
216 LOG_STRERROR (GNUNET_ERROR_TYPE_ERROR, "kill");
217 GNUNET_break (GNUNET_OK == GNUNET_OS_process_wait (genproc));
218 GNUNET_OS_process_close (genproc);
225 ret = GNUNET_OS_process_status (genproc, &type, &code);
226 if (ret == GNUNET_NO)
227 return; /* still running */
228 if (ret == GNUNET_SYSERR)
233 if (0 != GNUNET_OS_process_kill (genproc, SIGTERM))
234 LOG_STRERROR (GNUNET_ERROR_TYPE_ERROR, "kill");
235 GNUNET_break (GNUNET_OK == GNUNET_OS_process_wait (genproc));
236 GNUNET_OS_process_close (genproc);
239 LOG (GNUNET_ERROR_TYPE_INFO,
240 _("Starting `%s' process to generate entropy\n"), "find");
242 GNUNET_OS_start_process (NULL, NULL, "sh", "sh", "-c",
243 "exec find / -mount -type f -exec cp {} /dev/null \\; 2>/dev/null",
253 GNUNET_OS_process_kill (genproc, SIGKILL);
254 GNUNET_OS_process_close (genproc);
260 void __attribute__ ((constructor)) GNUNET_CRYPTO_random_init ()
262 gcry_control (GCRYCTL_DISABLE_SECMEM, 0);
263 if (!gcry_check_version (GCRYPT_VERSION))
267 ("libgcrypt has not the expected version (version %s is required).\n"),
271 #ifdef gcry_fast_random_poll
272 gcry_fast_random_poll ();
274 gcry_set_progress_handler (&entropy_generator, NULL);
276 SRANDOM (time (NULL) ^
277 GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_NONCE,
282 void __attribute__ ((destructor)) GNUNET_CRYPTO_random_fini ()
284 gcry_set_progress_handler (NULL, NULL);
289 /* end of crypto_random.c */