2 This file is part of GNUnet. Copyright (C) 2001-2014 Christian Grothoff
3 (and other contributing authors)
5 GNUnet is free software: you can redistribute it and/or modify it
6 under the terms of the GNU Affero General Public License as published
7 by the Free Software Foundation, either version 3 of the License,
8 or (at your option) any later version.
10 GNUnet is distributed in the hope that it will be useful, but
11 WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Affero General Public License for more details.
15 You should have received a copy of the GNU Affero General Public License
16 along with this program. If not, see <http://www.gnu.org/licenses/>.
21 * @file util/crypto_random.c
22 * @brief functions to gather random numbers
23 * @author Christian Grothoff
26 #include "gnunet_crypto_lib.h"
29 #define LOG(kind,...) GNUNET_log_from (kind, "util-crypto-random", __VA_ARGS__)
31 #define LOG_STRERROR(kind,syscall) GNUNET_log_from_strerror (kind, "util-crypto-random", syscall)
34 /* TODO: ndurner, move this to plibc? */
35 /* The code is derived from glibc, obviously */
36 #if !HAVE_RANDOM || !HAVE_SRANDOM
43 #define RANDOM() glibc_weak_rand32()
44 #define SRANDOM(s) glibc_weak_srand32(s)
48 #define RAND_MAX 0x7fffffff /* Hopefully this is correct */
51 static int32_t glibc_weak_rand32_state = 1;
55 glibc_weak_srand32 (int32_t s)
57 glibc_weak_rand32_state = s;
64 int32_t val = glibc_weak_rand32_state;
66 val = ((glibc_weak_rand32_state * 1103515245) + 12345) & 0x7fffffff;
67 glibc_weak_rand32_state = val;
73 * Create a cryptographically weak pseudo-random number in the interval of 0 to 1.
75 * @return number between 0 and 1.
80 return ((double) RANDOM () / RAND_MAX);
85 * Seed a weak random generator. Only #GNUNET_CRYPTO_QUALITY_WEAK-mode generator
88 * @param seed the seed to use
91 GNUNET_CRYPTO_seed_weak_random (int32_t seed)
99 * Fill block with a random values.
101 * @param mode desired quality of the random number
102 * @param buffer the buffer to fill
103 * @param length buffer length
106 GNUNET_CRYPTO_random_block (enum GNUNET_CRYPTO_Quality mode, void *buffer, size_t length)
108 #ifdef gcry_fast_random_poll
109 static unsigned int invokeCount;
113 case GNUNET_CRYPTO_QUALITY_STRONG:
114 /* see http://lists.gnupg.org/pipermail/gcrypt-devel/2004-May/000613.html */
115 #ifdef gcry_fast_random_poll
116 if ((invokeCount++ % 256) == 0)
117 gcry_fast_random_poll ();
119 gcry_randomize (buffer, length, GCRY_STRONG_RANDOM);
121 case GNUNET_CRYPTO_QUALITY_NONCE:
122 gcry_create_nonce (buffer, length);
124 case GNUNET_CRYPTO_QUALITY_WEAK:
125 /* see http://lists.gnupg.org/pipermail/gcrypt-devel/2004-May/000613.html */
126 #ifdef gcry_fast_random_poll
127 if ((invokeCount++ % 256) == 0)
128 gcry_fast_random_poll ();
130 gcry_randomize (buffer, length, GCRY_WEAK_RANDOM);
139 * Produce a random unsigned 32-bit number modulo @a i.
141 * @param mode desired quality of the random number
142 * @param i the upper limit (exclusive) for the random number
143 * @return a random value in the interval [0,i[.
146 GNUNET_CRYPTO_random_u32 (enum GNUNET_CRYPTO_Quality mode,
149 #ifdef gcry_fast_random_poll
150 static unsigned int invokeCount;
155 GNUNET_assert (i > 0);
159 case GNUNET_CRYPTO_QUALITY_STRONG:
160 /* see http://lists.gnupg.org/pipermail/gcrypt-devel/2004-May/000613.html */
161 #ifdef gcry_fast_random_poll
162 if ((invokeCount++ % 256) == 0)
163 gcry_fast_random_poll ();
165 ul = UINT32_MAX - (UINT32_MAX % i);
168 gcry_randomize ((unsigned char *) &ret, sizeof (uint32_t),
173 case GNUNET_CRYPTO_QUALITY_NONCE:
174 ul = UINT32_MAX - (UINT32_MAX % i);
177 gcry_create_nonce (&ret, sizeof (ret));
181 case GNUNET_CRYPTO_QUALITY_WEAK:
182 ret = i * get_weak_random ();
194 * Get an array with a random permutation of the
196 * @param mode #GNUNET_RANDOM_QUALITY_STRONG if the strong (but expensive)
197 * PRNG should be used, #GNUNET_RANDOM_QUALITY_WEAK otherwise
198 * @param n the size of the array
199 * @return the permutation array (allocated from heap)
202 GNUNET_CRYPTO_random_permute (enum GNUNET_CRYPTO_Quality mode,
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);
226 * Generate random unsigned 64-bit value.
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 * Initialize libgcrypt.
274 void __attribute__ ((constructor))
275 GNUNET_CRYPTO_random_init ()
279 if (! gcry_check_version (NEED_LIBGCRYPT_VERSION))
282 _("libgcrypt has not the expected version (version %s is required).\n"),
283 NEED_LIBGCRYPT_VERSION);
286 if ((rc = gcry_control (GCRYCTL_DISABLE_SECMEM, 0)))
288 "Failed to set libgcrypt option %s: %s\n",
291 /* Otherwise gnunet-ecc takes forever to complete, besides
292 we are fine with "just" using GCRY_STRONG_RANDOM */
293 if ((rc = gcry_control (GCRYCTL_ENABLE_QUICK_RANDOM, 0)))
295 "Failed to set libgcrypt option %s: %s\n",
296 "ENABLE_QUICK_RANDOM",
298 gcry_control (GCRYCTL_INITIALIZATION_FINISHED, 0);
299 gcry_fast_random_poll ();
300 GNUNET_CRYPTO_seed_weak_random (time (NULL) ^
301 GNUNET_CRYPTO_random_u32
302 (GNUNET_CRYPTO_QUALITY_NONCE, UINT32_MAX));
307 * Nicely shut down libgcrypt.
309 void __attribute__ ((destructor))
310 GNUNET_CRYPTO_random_fini ()
312 gcry_set_progress_handler (NULL, NULL);
313 #ifdef GCRYCTL_CLOSE_RANDOM_DEVICE
314 (void) gcry_control (GCRYCTL_CLOSE_RANDOM_DEVICE, 0);
320 /* end of crypto_random.c */