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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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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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)
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)
51 #define RAND_MAX 0x7fffffff /* Hopefully this is correct */
52 static int32_t glibc_weak_rand32_state = 1;
55 glibc_weak_srand32 (int32_t s)
57 glibc_weak_rand32_state = s;
63 int32_t val = glibc_weak_rand32_state;
65 val = ((glibc_weak_rand32_state * 1103515245) + 12345) & 0x7fffffff;
66 glibc_weak_rand32_state = val;
72 * Create a cryptographically weak pseudo-random number in the interval of 0 to 1.
74 * @return number between 0 and 1.
79 return ((double) RANDOM () / RAND_MAX);
83 * Seed a weak random generator. Only GNUNET_CRYPTO_QUALITY_WEAK-mode generator
86 * @param seed the seed to use
89 GNUNET_CRYPTO_seed_weak_random (int32_t seed)
95 * Produce a random value.
97 * @param mode desired quality of the random number
98 * @param i the upper limit (exclusive) for the random number
99 * @return a random value in the interval [0,i[.
102 GNUNET_CRYPTO_random_u32 (enum GNUNET_CRYPTO_Quality mode, uint32_t i)
104 #ifdef gcry_fast_random_poll
105 static unsigned int invokeCount;
110 GNUNET_assert (i > 0);
114 case GNUNET_CRYPTO_QUALITY_STRONG:
115 /* see http://lists.gnupg.org/pipermail/gcrypt-devel/2004-May/000613.html */
116 #ifdef gcry_fast_random_poll
117 if ((invokeCount++ % 256) == 0)
118 gcry_fast_random_poll ();
120 ul = UINT32_MAX - (UINT32_MAX % i);
123 gcry_randomize ((unsigned char *) &ret, sizeof (uint32_t),
128 case GNUNET_CRYPTO_QUALITY_NONCE:
129 ul = UINT32_MAX - (UINT32_MAX % i);
132 gcry_create_nonce (&ret, sizeof (ret));
136 case GNUNET_CRYPTO_QUALITY_WEAK:
137 ret = i * weak_random ();
149 * Get an array with a random permutation of the
151 * @param mode GNUNET_RANDOM_QUALITY_STRONG if the strong (but expensive)
152 * PRNG should be used, GNUNET_RANDOM_QUALITY_WEAK otherwise
153 * @param n the size of the array
154 * @return the permutation array (allocated from heap)
157 GNUNET_CRYPTO_random_permute (enum GNUNET_CRYPTO_Quality mode, unsigned int n)
164 GNUNET_assert (n > 0);
165 ret = GNUNET_malloc (n * sizeof (unsigned int));
166 for (i = 0; i < n; i++)
168 for (i = n - 1; i > 0; i--)
170 x = GNUNET_CRYPTO_random_u32 (mode, i + 1);
179 * Random on unsigned 64-bit values.
182 * @param mode desired quality of the random number
183 * @param max value returned will be in range [0,max) (exclusive)
184 * @return random 64-bit number
187 GNUNET_CRYPTO_random_u64 (enum GNUNET_CRYPTO_Quality mode, uint64_t max)
192 GNUNET_assert (max > 0);
195 case GNUNET_CRYPTO_QUALITY_STRONG:
196 ul = UINT64_MAX - (UINT64_MAX % max);
199 gcry_randomize ((unsigned char *) &ret, sizeof (uint64_t),
204 case GNUNET_CRYPTO_QUALITY_NONCE:
205 ul = UINT64_MAX - (UINT64_MAX % max);
208 gcry_create_nonce (&ret, sizeof (ret));
213 case GNUNET_CRYPTO_QUALITY_WEAK:
214 ret = max * weak_random ();
225 * This function should only be called in testcases
226 * where strong entropy gathering is not desired
227 * (for example, for hostkey generation).
230 GNUNET_CRYPTO_random_disable_entropy_gathering ()
232 gcry_control (GCRYCTL_ENABLE_QUICK_RANDOM, 0);
237 * Process ID of the "find" process that we use for
240 static struct GNUNET_OS_Process *genproc;
243 * Function called by libgcrypt whenever we are
244 * blocked gathering entropy.
247 entropy_generator (void *cls, const char *what, int printchar, int current,
251 enum GNUNET_OS_ProcessStatusType type;
254 if (0 != strcmp (what, "need_entropy"))
256 if (current == total)
260 if (0 != GNUNET_OS_process_kill (genproc, SIGTERM))
261 LOG_STRERROR (GNUNET_ERROR_TYPE_ERROR, "kill");
262 GNUNET_break (GNUNET_OK == GNUNET_OS_process_wait (genproc));
263 GNUNET_OS_process_destroy (genproc);
270 ret = GNUNET_OS_process_status (genproc, &type, &code);
271 if (ret == GNUNET_NO)
272 return; /* still running */
273 if (ret == GNUNET_SYSERR)
278 if (0 != GNUNET_OS_process_kill (genproc, SIGTERM))
279 LOG_STRERROR (GNUNET_ERROR_TYPE_ERROR, "kill");
280 GNUNET_break (GNUNET_OK == GNUNET_OS_process_wait (genproc));
281 GNUNET_OS_process_destroy (genproc);
284 LOG (GNUNET_ERROR_TYPE_INFO, _("Starting `%s' process to generate entropy\n"),
287 GNUNET_OS_start_process (GNUNET_NO, 0,
288 NULL, NULL, "sh", "sh", "-c",
289 "exec find / -mount -type f -exec cp {} /dev/null \\; 2>/dev/null",
299 GNUNET_OS_process_kill (genproc, SIGKILL);
300 GNUNET_OS_process_destroy (genproc);
306 void __attribute__ ((constructor)) GNUNET_CRYPTO_random_init ()
308 gcry_control (GCRYCTL_DISABLE_SECMEM, 0);
309 if (!gcry_check_version (GCRYPT_VERSION))
313 ("libgcrypt has not the expected version (version %s is required).\n"),
317 #ifdef GCRYCTL_INITIALIZATION_FINISHED
318 gcry_control (GCRYCTL_INITIALIZATION_FINISHED, 0);
320 #ifdef gcry_fast_random_poll
321 gcry_fast_random_poll ();
323 gcry_set_progress_handler (&entropy_generator, NULL);
325 GNUNET_CRYPTO_seed_weak_random (time (NULL) ^
326 GNUNET_CRYPTO_random_u32
327 (GNUNET_CRYPTO_QUALITY_NONCE, UINT32_MAX));
331 void __attribute__ ((destructor)) GNUNET_CRYPTO_random_fini ()
333 gcry_set_progress_handler (NULL, NULL);
338 /* end of crypto_random.c */