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3 (C) 2001, 2002, 2003, 2004, 2005, 2006 Christian Grothoff (and other contributing authors)
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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);
65 case GNUNET_CRYPTO_QUALITY_STRONG:
66 /* see http://lists.gnupg.org/pipermail/gcrypt-devel/2004-May/000613.html */
67 #ifdef gcry_fast_random_poll
68 if ((invokeCount++ % 256) == 0)
69 gcry_fast_random_poll ();
71 ul = UINT32_MAX - (UINT32_MAX % i);
74 gcry_randomize ((unsigned char *) &ret, sizeof (uint32_t),
79 case GNUNET_CRYPTO_QUALITY_NONCE:
80 ul = UINT32_MAX - (UINT32_MAX % i);
83 gcry_create_nonce (&ret, sizeof (ret));
87 case GNUNET_CRYPTO_QUALITY_WEAK:
88 ret = i * weak_random ();
100 * Get an array with a random permutation of the
102 * @param mode GNUNET_RANDOM_QUALITY_STRONG if the strong (but expensive)
103 * PRNG should be used, GNUNET_RANDOM_QUALITY_WEAK otherwise
104 * @param n the size of the array
105 * @return the permutation array (allocated from heap)
108 GNUNET_CRYPTO_random_permute (enum GNUNET_CRYPTO_Quality mode, unsigned int n)
115 GNUNET_assert (n > 0);
116 ret = GNUNET_malloc (n * sizeof (unsigned int));
117 for (i = 0; i < n; i++)
119 for (i = n - 1; i > 0; i--)
121 x = GNUNET_CRYPTO_random_u32 (mode, i + 1);
130 * Random on unsigned 64-bit values.
133 * @param mode desired quality of the random number
134 * @param max value returned will be in range [0,max) (exclusive)
135 * @return random 64-bit number
138 GNUNET_CRYPTO_random_u64 (enum GNUNET_CRYPTO_Quality mode, uint64_t max)
143 GNUNET_assert (max > 0);
146 case GNUNET_CRYPTO_QUALITY_STRONG:
147 ul = UINT64_MAX - (UINT64_MAX % max);
150 gcry_randomize ((unsigned char *) &ret, sizeof (uint64_t),
155 case GNUNET_CRYPTO_QUALITY_NONCE:
156 ul = UINT64_MAX - (UINT64_MAX % max);
159 gcry_create_nonce (&ret, sizeof (ret));
164 case GNUNET_CRYPTO_QUALITY_WEAK:
165 ret = max * weak_random ();
176 * This function should only be called in testcases
177 * where strong entropy gathering is not desired
178 * (for example, for hostkey generation).
181 GNUNET_CRYPTO_random_disable_entropy_gathering ()
183 gcry_control (GCRYCTL_ENABLE_QUICK_RANDOM, 0);
188 * Process ID of the "find" process that we use for
191 static struct GNUNET_OS_Process *genproc;
194 * Function called by libgcrypt whenever we are
195 * blocked gathering entropy.
198 entropy_generator (void *cls, const char *what, int printchar, int current,
202 enum GNUNET_OS_ProcessStatusType type;
205 if (0 != strcmp (what, "need_entropy"))
207 if (current == total)
211 if (0 != GNUNET_OS_process_kill (genproc, SIGTERM))
212 GNUNET_log_strerror (GNUNET_ERROR_TYPE_ERROR, "kill");
213 GNUNET_break (GNUNET_OK == GNUNET_OS_process_wait (genproc));
214 GNUNET_OS_process_close (genproc);
221 ret = GNUNET_OS_process_status (genproc, &type, &code);
222 if (ret == GNUNET_NO)
223 return; /* still running */
224 if (ret == GNUNET_SYSERR)
229 if (0 != GNUNET_OS_process_kill (genproc, SIGTERM))
230 GNUNET_log_strerror (GNUNET_ERROR_TYPE_ERROR, "kill");
231 GNUNET_break (GNUNET_OK == GNUNET_OS_process_wait (genproc));
232 GNUNET_OS_process_close (genproc);
235 GNUNET_log (GNUNET_ERROR_TYPE_INFO,
236 _("Starting `%s' process to generate entropy\n"), "find");
238 GNUNET_OS_start_process (NULL, NULL, "sh", "sh", "-c",
239 "exec find / -mount -type f -exec cp {} /dev/null \\; 2>/dev/null",
249 GNUNET_OS_process_kill (genproc, SIGKILL);
250 GNUNET_OS_process_close (genproc);
256 void __attribute__ ((constructor)) GNUNET_CRYPTO_random_init ()
258 gcry_control (GCRYCTL_DISABLE_SECMEM, 0);
259 if (!gcry_check_version (GCRYPT_VERSION))
263 ("libgcrypt has not the expected version (version %s is required).\n"),
267 #ifdef gcry_fast_random_poll
268 gcry_fast_random_poll ();
270 gcry_set_progress_handler (&entropy_generator, NULL);
272 SRANDOM (time (NULL) ^
273 GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_NONCE, UINT32_MAX));
277 void __attribute__ ((destructor)) GNUNET_CRYPTO_random_fini ()
279 gcry_set_progress_handler (NULL, NULL);
284 /* end of crypto_random.c */