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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_util_lib.h"
31 #define LOG(kind,...) GNUNET_log_from (kind, "util", __VA_ARGS__)
33 #define LOG_STRERROR(kind,syscall) GNUNET_log_from_strerror (kind, "util", syscall)
36 /* TODO: ndurner, move this to plibc? */
37 /* The code is derived from glibc, obviously */
38 #if !HAVE_RANDOM || !HAVE_SRANDOM
45 #define RANDOM() glibc_weak_rand32()
46 #define SRANDOM(s) glibc_weak_srand32(s)
50 #define RAND_MAX 0x7fffffff /* Hopefully this is correct */
53 static int32_t glibc_weak_rand32_state = 1;
57 glibc_weak_srand32 (int32_t s)
59 glibc_weak_rand32_state = s;
66 int32_t val = glibc_weak_rand32_state;
68 val = ((glibc_weak_rand32_state * 1103515245) + 12345) & 0x7fffffff;
69 glibc_weak_rand32_state = val;
75 * Create a cryptographically weak pseudo-random number in the interval of 0 to 1.
77 * @return number between 0 and 1.
82 return ((double) RANDOM () / RAND_MAX);
87 * Seed a weak random generator. Only GNUNET_CRYPTO_QUALITY_WEAK-mode generator
90 * @param seed the seed to use
93 GNUNET_CRYPTO_seed_weak_random (int32_t seed)
100 * Fill block with a random values.
102 * @param mode desired quality of the random number
103 * @param buffer the buffer to fill
104 * @param length buffer length
107 GNUNET_CRYPTO_random_block (enum GNUNET_CRYPTO_Quality mode, void *buffer, size_t length)
109 #ifdef gcry_fast_random_poll
110 static unsigned int invokeCount;
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 gcry_randomize (buffer, length, GCRY_STRONG_RANDOM);
122 case GNUNET_CRYPTO_QUALITY_NONCE:
123 gcry_create_nonce (buffer, length);
125 case GNUNET_CRYPTO_QUALITY_WEAK:
126 /* see http://lists.gnupg.org/pipermail/gcrypt-devel/2004-May/000613.html */
127 #ifdef gcry_fast_random_poll
128 if ((invokeCount++ % 256) == 0)
129 gcry_fast_random_poll ();
131 gcry_randomize (buffer, length, GCRY_WEAK_RANDOM);
141 * Produce a random value.
143 * @param mode desired quality of the random number
144 * @param i the upper limit (exclusive) for the random number
145 * @return a random value in the interval [0,i[.
148 GNUNET_CRYPTO_random_u32 (enum GNUNET_CRYPTO_Quality mode, uint32_t i)
150 #ifdef gcry_fast_random_poll
151 static unsigned int invokeCount;
156 GNUNET_assert (i > 0);
160 case GNUNET_CRYPTO_QUALITY_STRONG:
161 /* see http://lists.gnupg.org/pipermail/gcrypt-devel/2004-May/000613.html */
162 #ifdef gcry_fast_random_poll
163 if ((invokeCount++ % 256) == 0)
164 gcry_fast_random_poll ();
166 ul = UINT32_MAX - (UINT32_MAX % i);
169 gcry_randomize ((unsigned char *) &ret, sizeof (uint32_t),
174 case GNUNET_CRYPTO_QUALITY_NONCE:
175 ul = UINT32_MAX - (UINT32_MAX % i);
178 gcry_create_nonce (&ret, sizeof (ret));
182 case GNUNET_CRYPTO_QUALITY_WEAK:
183 ret = i * get_weak_random ();
195 * Get an array with a random permutation of the
197 * @param mode GNUNET_RANDOM_QUALITY_STRONG if the strong (but expensive)
198 * PRNG should be used, GNUNET_RANDOM_QUALITY_WEAK otherwise
199 * @param n the size of the array
200 * @return the permutation array (allocated from heap)
203 GNUNET_CRYPTO_random_permute (enum GNUNET_CRYPTO_Quality mode, unsigned int n)
210 GNUNET_assert (n > 0);
211 ret = GNUNET_malloc (n * sizeof (unsigned int));
212 for (i = 0; i < n; i++)
214 for (i = n - 1; i > 0; i--)
216 x = GNUNET_CRYPTO_random_u32 (mode, i + 1);
225 * Random on unsigned 64-bit values.
228 * @param mode desired quality of the random number
229 * @param max value returned will be in range [0,max) (exclusive)
230 * @return random 64-bit number
233 GNUNET_CRYPTO_random_u64 (enum GNUNET_CRYPTO_Quality mode, uint64_t max)
238 GNUNET_assert (max > 0);
241 case GNUNET_CRYPTO_QUALITY_STRONG:
242 ul = UINT64_MAX - (UINT64_MAX % max);
245 gcry_randomize ((unsigned char *) &ret, sizeof (uint64_t),
250 case GNUNET_CRYPTO_QUALITY_NONCE:
251 ul = UINT64_MAX - (UINT64_MAX % max);
254 gcry_create_nonce (&ret, sizeof (ret));
259 case GNUNET_CRYPTO_QUALITY_WEAK:
260 ret = max * get_weak_random ();
272 * Process ID of the "find" process that we use for
275 static struct GNUNET_OS_Process *genproc;
279 * Function called by libgcrypt whenever we are
280 * blocked gathering entropy.
283 entropy_generator (void *cls, const char *what, int printchar, int current,
287 enum GNUNET_OS_ProcessStatusType type;
290 if (0 != strcmp (what, "need_entropy"))
292 if (current == total)
296 if (0 != GNUNET_OS_process_kill (genproc, SIGKILL))
297 LOG_STRERROR (GNUNET_ERROR_TYPE_ERROR, "kill");
298 GNUNET_break (GNUNET_OK == GNUNET_OS_process_wait (genproc));
299 GNUNET_OS_process_destroy (genproc);
306 ret = GNUNET_OS_process_status (genproc, &type, &code);
307 if (ret == GNUNET_NO)
308 return; /* still running */
309 if (ret == GNUNET_SYSERR)
314 if (0 != GNUNET_OS_process_kill (genproc, SIGKILL))
315 LOG_STRERROR (GNUNET_ERROR_TYPE_ERROR, "kill");
316 GNUNET_break (GNUNET_OK == GNUNET_OS_process_wait (genproc));
317 GNUNET_OS_process_destroy (genproc);
320 LOG (GNUNET_ERROR_TYPE_INFO, _("Starting `%s' process to generate entropy\n"),
323 GNUNET_OS_start_process (GNUNET_NO, 0,
324 NULL, NULL, "sh", "sh", "-c",
325 "exec find / -mount -type f -exec cp {} /dev/null \\; 2>/dev/null",
335 GNUNET_OS_process_kill (genproc, SIGKILL);
336 GNUNET_OS_process_destroy (genproc);
342 void __attribute__ ((constructor))
343 GNUNET_CRYPTO_random_init ()
347 if (! gcry_check_version (NEED_LIBGCRYPT_VERSION))
351 ("libgcrypt has not the expected version (version %s is required).\n"),
352 NEED_LIBGCRYPT_VERSION);
355 if ((rc = gcry_control (GCRYCTL_DISABLE_SECMEM, 0)))
356 FPRINTF (stderr, "Failed to set libgcrypt option %s: %s\n", "DISABLE_SECMEM",
358 /* we only generate ephemeral keys in-process; for those,
359 we are fine with "just" using GCRY_STRONG_RANDOM */
360 if ((rc = gcry_control (GCRYCTL_ENABLE_QUICK_RANDOM, 0)))
361 FPRINTF (stderr, "Failed to set libgcrypt option %s: %s\n", "ENABLE_QUICK_RANDOM",
364 #ifdef GCRYCTL_INITIALIZATION_FINISHED
365 gcry_control (GCRYCTL_INITIALIZATION_FINISHED, 0);
367 #ifdef gcry_fast_random_poll
368 gcry_fast_random_poll ();
370 gcry_set_progress_handler (&entropy_generator, NULL);
372 GNUNET_CRYPTO_seed_weak_random (time (NULL) ^
373 GNUNET_CRYPTO_random_u32
374 (GNUNET_CRYPTO_QUALITY_NONCE, UINT32_MAX));
378 void __attribute__ ((destructor))
379 GNUNET_CRYPTO_random_fini ()
381 gcry_set_progress_handler (NULL, NULL);
386 /* end of crypto_random.c */