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3 (C) 2001, 2002, 2003, 2004, 2005, 2006 Christian Grothoff (and other contributing authors)
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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);
79 else if (mode == GNUNET_CRYPTO_QUALITY_NONCE)
81 ul = UINT32_MAX - (UINT32_MAX % i);
84 gcry_create_nonce(&ret, sizeof(ret));
92 ret = i * weak_random ();
101 * Get an array with a random permutation of the
103 * @param mode GNUNET_RANDOM_QUALITY_STRONG if the strong (but expensive)
104 * PRNG should be used, GNUNET_RANDOM_QUALITY_WEAK otherwise
105 * @param n the size of the array
106 * @return the permutation array (allocated from heap)
109 GNUNET_CRYPTO_random_permute (enum GNUNET_CRYPTO_Quality mode, unsigned int n)
116 GNUNET_assert (n > 0);
117 ret = GNUNET_malloc (n * sizeof (unsigned int));
118 for (i = 0; i < n; i++)
120 for (i = n - 1; i > 0; i--)
122 x = GNUNET_CRYPTO_random_u32 (mode, i+1);
131 * Random on unsigned 64-bit values.
134 * @param mode desired quality of the random number
135 * @param max value returned will be in range [0,max) (exclusive)
136 * @return random 64-bit number
139 GNUNET_CRYPTO_random_u64 (enum GNUNET_CRYPTO_Quality mode, uint64_t max)
144 GNUNET_assert (max > 0);
145 if (mode == GNUNET_CRYPTO_QUALITY_STRONG)
147 ul = UINT64_MAX - (UINT64_MAX % max);
150 gcry_randomize ((unsigned char *) &ret,
151 sizeof (uint64_t), GCRY_STRONG_RANDOM);
156 else if (mode == GNUNET_CRYPTO_QUALITY_NONCE)
158 ul = UINT64_MAX - (UINT64_MAX % max);
161 gcry_create_nonce(&ret, sizeof(ret));
169 ret = max * weak_random ();
177 * This function should only be called in testcases
178 * where strong entropy gathering is not desired
179 * (for example, for hostkey generation).
182 GNUNET_CRYPTO_random_disable_entropy_gathering ()
184 gcry_control (GCRYCTL_ENABLE_QUICK_RANDOM, 0);
189 * Process ID of the "find" process that we use for
192 static pid_t genproc;
195 * Function called by libgcrypt whenever we are
196 * blocked gathering entropy.
199 entropy_generator (void *cls,
200 const char *what, int printchar, int current, int total)
203 enum GNUNET_OS_ProcessStatusType type;
206 if (0 != strcmp (what, "need_entropy"))
208 if (current == total)
212 if (0 != PLIBC_KILL (genproc, SIGTERM))
213 GNUNET_log_strerror (GNUNET_ERROR_TYPE_ERROR, "kill");
214 GNUNET_break (GNUNET_OK == GNUNET_OS_process_wait (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 != PLIBC_KILL (genproc, SIGTERM))
230 GNUNET_log_strerror (GNUNET_ERROR_TYPE_ERROR, "kill");
231 GNUNET_break (GNUNET_OK == GNUNET_OS_process_wait (genproc));
234 GNUNET_log (GNUNET_ERROR_TYPE_INFO,
235 _("Starting `%s' process to generate entropy\n"), "find");
236 genproc = GNUNET_OS_start_process (NULL, NULL, "sh",
239 "exec find / -mount -type f -exec cp {} /dev/null \\; 2>/dev/null",
249 PLIBC_KILL (genproc, SIGKILL);
255 void __attribute__ ((constructor)) GNUNET_CRYPTO_random_init ()
257 SRANDOM (time (NULL));
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);
275 void __attribute__ ((destructor)) GNUNET_CRYPTO_random_fini ()
277 gcry_set_progress_handler (NULL, NULL);
282 /* end of crypto_random.c */