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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"
33 #define LOG(kind,...) GNUNET_log_from (kind, "util", __VA_ARGS__)
35 #define LOG_STRERROR(kind,syscall) GNUNET_log_from_strerror (kind, "util", syscall)
37 /* TODO: ndurner, move this to plibc? */
38 /* The code is derived from glibc, obviously */
46 #define RANDOM() glibc_weak_rand32()
47 #define SRANDOM(s) glibc_weak_srand32(s)
48 static int32_t glibc_weak_rand32_state = 1;
51 glibc_weak_srand32 (int32_t s)
53 glibc_weak_rand32_state = s;
59 int32_t val = glibc_weak_rand32_state;
61 val = ((glibc_weak_rand32_state * 1103515245) + 12345) & 0x7fffffff;
62 glibc_weak_rand32_state = val;
68 * Create a cryptographically weak pseudo-random number in the interval of 0 to 1.
70 * @return number between 0 and 1.
75 return ((double) RANDOM () / RAND_MAX);
79 * Seed a weak random generator. Only GNUNET_CRYPTO_QUALITY_WEAK-mode generator
82 * @param seed the seed to use
85 GNUNET_CRYPTO_seed_weak_random (int32_t seed)
91 * Produce a random value.
93 * @param mode desired quality of the random number
94 * @param i the upper limit (exclusive) for the random number
95 * @return a random value in the interval [0,i[.
98 GNUNET_CRYPTO_random_u32 (enum GNUNET_CRYPTO_Quality mode, uint32_t i)
100 #ifdef gcry_fast_random_poll
101 static unsigned int invokeCount;
106 GNUNET_assert (i > 0);
110 case GNUNET_CRYPTO_QUALITY_STRONG:
111 /* see http://lists.gnupg.org/pipermail/gcrypt-devel/2004-May/000613.html */
112 #ifdef gcry_fast_random_poll
113 if ((invokeCount++ % 256) == 0)
114 gcry_fast_random_poll ();
116 ul = UINT32_MAX - (UINT32_MAX % i);
119 gcry_randomize ((unsigned char *) &ret, sizeof (uint32_t),
124 case GNUNET_CRYPTO_QUALITY_NONCE:
125 ul = UINT32_MAX - (UINT32_MAX % i);
128 gcry_create_nonce (&ret, sizeof (ret));
132 case GNUNET_CRYPTO_QUALITY_WEAK:
133 ret = i * weak_random ();
145 * Get an array with a random permutation of the
147 * @param mode GNUNET_RANDOM_QUALITY_STRONG if the strong (but expensive)
148 * PRNG should be used, GNUNET_RANDOM_QUALITY_WEAK otherwise
149 * @param n the size of the array
150 * @return the permutation array (allocated from heap)
153 GNUNET_CRYPTO_random_permute (enum GNUNET_CRYPTO_Quality mode, unsigned int n)
160 GNUNET_assert (n > 0);
161 ret = GNUNET_malloc (n * sizeof (unsigned int));
162 for (i = 0; i < n; i++)
164 for (i = n - 1; i > 0; i--)
166 x = GNUNET_CRYPTO_random_u32 (mode, i + 1);
175 * Random on unsigned 64-bit values.
178 * @param mode desired quality of the random number
179 * @param max value returned will be in range [0,max) (exclusive)
180 * @return random 64-bit number
183 GNUNET_CRYPTO_random_u64 (enum GNUNET_CRYPTO_Quality mode, uint64_t max)
188 GNUNET_assert (max > 0);
191 case GNUNET_CRYPTO_QUALITY_STRONG:
192 ul = UINT64_MAX - (UINT64_MAX % max);
195 gcry_randomize ((unsigned char *) &ret, sizeof (uint64_t),
200 case GNUNET_CRYPTO_QUALITY_NONCE:
201 ul = UINT64_MAX - (UINT64_MAX % max);
204 gcry_create_nonce (&ret, sizeof (ret));
209 case GNUNET_CRYPTO_QUALITY_WEAK:
210 ret = max * weak_random ();
221 * This function should only be called in testcases
222 * where strong entropy gathering is not desired
223 * (for example, for hostkey generation).
226 GNUNET_CRYPTO_random_disable_entropy_gathering ()
228 gcry_control (GCRYCTL_ENABLE_QUICK_RANDOM, 0);
233 * Process ID of the "find" process that we use for
236 static struct GNUNET_OS_Process *genproc;
239 * Function called by libgcrypt whenever we are
240 * blocked gathering entropy.
243 entropy_generator (void *cls, const char *what, int printchar, int current,
247 enum GNUNET_OS_ProcessStatusType type;
250 if (0 != strcmp (what, "need_entropy"))
252 if (current == total)
256 if (0 != GNUNET_OS_process_kill (genproc, SIGTERM))
257 LOG_STRERROR (GNUNET_ERROR_TYPE_ERROR, "kill");
258 GNUNET_break (GNUNET_OK == GNUNET_OS_process_wait (genproc));
259 GNUNET_OS_process_close (genproc);
266 ret = GNUNET_OS_process_status (genproc, &type, &code);
267 if (ret == GNUNET_NO)
268 return; /* still running */
269 if (ret == GNUNET_SYSERR)
274 if (0 != GNUNET_OS_process_kill (genproc, SIGTERM))
275 LOG_STRERROR (GNUNET_ERROR_TYPE_ERROR, "kill");
276 GNUNET_break (GNUNET_OK == GNUNET_OS_process_wait (genproc));
277 GNUNET_OS_process_close (genproc);
280 LOG (GNUNET_ERROR_TYPE_INFO, _("Starting `%s' process to generate entropy\n"),
283 GNUNET_OS_start_process (NULL, NULL, "sh", "sh", "-c",
284 "exec find / -mount -type f -exec cp {} /dev/null \\; 2>/dev/null",
294 GNUNET_OS_process_kill (genproc, SIGKILL);
295 GNUNET_OS_process_close (genproc);
301 void __attribute__ ((constructor)) GNUNET_CRYPTO_random_init ()
303 gcry_control (GCRYCTL_DISABLE_SECMEM, 0);
304 if (!gcry_check_version (GCRYPT_VERSION))
308 ("libgcrypt has not the expected version (version %s is required).\n"),
312 #ifdef gcry_fast_random_poll
313 gcry_fast_random_poll ();
315 gcry_set_progress_handler (&entropy_generator, NULL);
317 GNUNET_CRYPTO_seed_weak_random (time (NULL) ^
318 GNUNET_CRYPTO_random_u32
319 (GNUNET_CRYPTO_QUALITY_NONCE, UINT32_MAX));
323 void __attribute__ ((destructor)) GNUNET_CRYPTO_random_fini ()
325 gcry_set_progress_handler (NULL, NULL);
330 /* end of crypto_random.c */