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/>.
18 SPDX-License-Identifier: AGPL3.0-or-later
23 * @file util/crypto_random.c
24 * @brief functions to gather random numbers
25 * @author Christian Grothoff
28 #include "gnunet_crypto_lib.h"
31 #define LOG(kind, ...) GNUNET_log_from(kind, "util-crypto-random", __VA_ARGS__)
33 #define LOG_STRERROR(kind, syscall) \
34 GNUNET_log_from_strerror(kind, "util-crypto-random", syscall)
37 /* TODO: ndurner, move this to plibc? */
38 /* The code is derived from glibc, obviously */
39 #if !HAVE_RANDOM || !HAVE_SRANDOM
46 #define RANDOM() glibc_weak_rand32()
47 #define SRANDOM(s) glibc_weak_srand32(s)
51 #define RAND_MAX 0x7fffffff /* Hopefully this is correct */
54 static int32_t glibc_weak_rand32_state = 1;
58 glibc_weak_srand32(int32_t s)
60 glibc_weak_rand32_state = s;
67 int32_t val = glibc_weak_rand32_state;
69 val = ((glibc_weak_rand32_state * 1103515245) + 12345) & 0x7fffffff;
70 glibc_weak_rand32_state = val;
76 * Create a cryptographically weak pseudo-random number in the interval of 0 to 1.
78 * @return number between 0 and 1.
83 return((double)random() / RAND_MAX);
88 * Seed a weak random generator. Only #GNUNET_CRYPTO_QUALITY_WEAK-mode generator
91 * @param seed the seed to use
94 GNUNET_CRYPTO_seed_weak_random(int32_t seed)
102 * Zero out @a buffer, securely against compiler optimizations.
103 * Used to delete key material.
105 * @param buffer the buffer to zap
106 * @param length buffer length
109 GNUNET_CRYPTO_zero_keys(void *buffer, size_t length)
112 memset_s(buffer, length, 0, length);
113 #elif HAVE_EXPLICIT_BZERO
114 explicit_bzero(buffer, length);
116 volatile unsigned char *p = buffer;
125 * Fill block with a random values.
127 * @param mode desired quality of the random number
128 * @param buffer the buffer to fill
129 * @param length buffer length
132 GNUNET_CRYPTO_random_block(enum GNUNET_CRYPTO_Quality mode,
136 #ifdef gcry_fast_random_poll
137 static unsigned int invokeCount;
141 case GNUNET_CRYPTO_QUALITY_STRONG:
142 /* see http://lists.gnupg.org/pipermail/gcrypt-devel/2004-May/000613.html */
143 #ifdef gcry_fast_random_poll
144 if ((invokeCount++ % 256) == 0)
145 gcry_fast_random_poll();
147 gcry_randomize(buffer, length, GCRY_STRONG_RANDOM);
150 case GNUNET_CRYPTO_QUALITY_NONCE:
151 gcry_create_nonce(buffer, length);
154 case GNUNET_CRYPTO_QUALITY_WEAK:
155 /* see http://lists.gnupg.org/pipermail/gcrypt-devel/2004-May/000613.html */
156 #ifdef gcry_fast_random_poll
157 if ((invokeCount++ % 256) == 0)
158 gcry_fast_random_poll();
160 gcry_randomize(buffer, length, GCRY_WEAK_RANDOM);
170 * Produce a random unsigned 32-bit number modulo @a i.
172 * @param mode desired quality of the random number
173 * @param i the upper limit (exclusive) for the random number
174 * @return a random value in the interval [0,i[.
177 GNUNET_CRYPTO_random_u32(enum GNUNET_CRYPTO_Quality mode, uint32_t i)
179 #ifdef gcry_fast_random_poll
180 static unsigned int invokeCount;
185 GNUNET_assert(i > 0);
189 case GNUNET_CRYPTO_QUALITY_STRONG:
190 /* see http://lists.gnupg.org/pipermail/gcrypt-devel/2004-May/000613.html */
191 #ifdef gcry_fast_random_poll
192 if ((invokeCount++ % 256) == 0)
193 gcry_fast_random_poll();
195 ul = UINT32_MAX - (UINT32_MAX % i);
198 gcry_randomize((unsigned char *)&ret,
205 case GNUNET_CRYPTO_QUALITY_NONCE:
206 ul = UINT32_MAX - (UINT32_MAX % i);
209 gcry_create_nonce(&ret, sizeof(ret));
214 case GNUNET_CRYPTO_QUALITY_WEAK:
215 ret = i * get_weak_random();
228 * Get an array with a random permutation of the
230 * @param mode #GNUNET_RANDOM_QUALITY_STRONG if the strong (but expensive)
231 * PRNG should be used, #GNUNET_RANDOM_QUALITY_WEAK otherwise
232 * @param n the size of the array
233 * @return the permutation array (allocated from heap)
236 GNUNET_CRYPTO_random_permute(enum GNUNET_CRYPTO_Quality mode, unsigned int n)
243 GNUNET_assert(n > 0);
244 ret = GNUNET_malloc(n * sizeof(unsigned int));
245 for (i = 0; i < n; i++)
247 for (i = n - 1; i > 0; i--)
249 x = GNUNET_CRYPTO_random_u32(mode, i + 1);
259 * Generate random unsigned 64-bit value.
261 * @param mode desired quality of the random number
262 * @param max value returned will be in range [0,max) (exclusive)
263 * @return random 64-bit number
266 GNUNET_CRYPTO_random_u64(enum GNUNET_CRYPTO_Quality mode, uint64_t max)
271 GNUNET_assert(max > 0);
274 case GNUNET_CRYPTO_QUALITY_STRONG:
275 ul = UINT64_MAX - (UINT64_MAX % max);
278 gcry_randomize((unsigned char *)&ret,
285 case GNUNET_CRYPTO_QUALITY_NONCE:
286 ul = UINT64_MAX - (UINT64_MAX % max);
289 gcry_create_nonce(&ret, sizeof(ret));
295 case GNUNET_CRYPTO_QUALITY_WEAK:
296 ret = max * get_weak_random();
309 * Allocation wrapper for libgcrypt, used to avoid bad locking
310 * strategy of libgcrypt implementation.
320 * Allocation wrapper for libgcrypt, used to avoid bad locking
321 * strategy of libgcrypt implementation.
324 w_check(const void *p)
327 return 0; /* not secure memory */
332 * Initialize libgcrypt.
334 void __attribute__ ((constructor)) GNUNET_CRYPTO_random_init()
338 if (!gcry_check_version(NEED_LIBGCRYPT_VERSION))
342 _("libgcrypt has not the expected version (version %s is required).\n"),
343 NEED_LIBGCRYPT_VERSION);
346 /* set custom allocators */
347 gcry_set_allocation_handler(&w_malloc, &w_malloc, &w_check, &realloc, &free);
348 /* Disable use of secure memory */
349 if ((rc = gcry_control(GCRYCTL_DISABLE_SECMEM, 0)))
351 "Failed to set libgcrypt option %s: %s\n",
354 /* Otherwise gnunet-ecc takes forever to complete, besides
355 we are fine with "just" using GCRY_STRONG_RANDOM */
356 if ((rc = gcry_control(GCRYCTL_ENABLE_QUICK_RANDOM, 0)))
358 "Failed to set libgcrypt option %s: %s\n",
359 "ENABLE_QUICK_RANDOM",
361 gcry_control(GCRYCTL_INITIALIZATION_FINISHED, 0);
362 gcry_fast_random_poll();
363 GNUNET_CRYPTO_seed_weak_random(
365 GNUNET_CRYPTO_random_u32(GNUNET_CRYPTO_QUALITY_NONCE, UINT32_MAX));
370 * Nicely shut down libgcrypt.
372 void __attribute__ ((destructor)) GNUNET_CRYPTO_random_fini()
374 gcry_set_progress_handler(NULL, NULL);
375 #ifdef GCRYCTL_CLOSE_RANDOM_DEVICE
376 (void)gcry_control(GCRYCTL_CLOSE_RANDOM_DEVICE, 0);
381 /* end of crypto_random.c */