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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)
101 * Fill block with a random values.
103 * @param mode desired quality of the random number
104 * @param buffer the buffer to fill
105 * @param length buffer length
108 GNUNET_CRYPTO_random_block (enum GNUNET_CRYPTO_Quality mode, void *buffer, size_t length)
110 #ifdef gcry_fast_random_poll
111 static unsigned int invokeCount;
115 case GNUNET_CRYPTO_QUALITY_STRONG:
116 /* see http://lists.gnupg.org/pipermail/gcrypt-devel/2004-May/000613.html */
117 #ifdef gcry_fast_random_poll
118 if ((invokeCount++ % 256) == 0)
119 gcry_fast_random_poll ();
121 gcry_randomize (buffer, length, GCRY_STRONG_RANDOM);
123 case GNUNET_CRYPTO_QUALITY_NONCE:
124 gcry_create_nonce (buffer, length);
126 case GNUNET_CRYPTO_QUALITY_WEAK:
127 /* see http://lists.gnupg.org/pipermail/gcrypt-devel/2004-May/000613.html */
128 #ifdef gcry_fast_random_poll
129 if ((invokeCount++ % 256) == 0)
130 gcry_fast_random_poll ();
132 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);
226 * Random on unsigned 64-bit values.
229 * @param mode desired quality of the random number
230 * @param max value returned will be in range [0,max) (exclusive)
231 * @return random 64-bit number
234 GNUNET_CRYPTO_random_u64 (enum GNUNET_CRYPTO_Quality mode, uint64_t max)
239 GNUNET_assert (max > 0);
242 case GNUNET_CRYPTO_QUALITY_STRONG:
243 ul = UINT64_MAX - (UINT64_MAX % max);
246 gcry_randomize ((unsigned char *) &ret, sizeof (uint64_t),
251 case GNUNET_CRYPTO_QUALITY_NONCE:
252 ul = UINT64_MAX - (UINT64_MAX % max);
255 gcry_create_nonce (&ret, sizeof (ret));
260 case GNUNET_CRYPTO_QUALITY_WEAK:
261 ret = max * get_weak_random ();
272 void __attribute__ ((constructor))
273 GNUNET_CRYPTO_random_init ()
277 if (! gcry_check_version (NEED_LIBGCRYPT_VERSION))
280 _("libgcrypt has not the expected version (version %s is required).\n"),
281 NEED_LIBGCRYPT_VERSION);
284 if ((rc = gcry_control (GCRYCTL_DISABLE_SECMEM, 0)))
286 "Failed to set libgcrypt option %s: %s\n",
289 /* we only generate ephemeral keys in-process; for those,
290 we are fine with "just" using GCRY_STRONG_RANDOM */
291 if ((rc = gcry_control (GCRYCTL_ENABLE_QUICK_RANDOM, 0)))
293 "Failed to set libgcrypt option %s: %s\n",
294 "ENABLE_QUICK_RANDOM",
296 gcry_control (GCRYCTL_INITIALIZATION_FINISHED, 0);
297 gcry_fast_random_poll ();
298 GNUNET_CRYPTO_seed_weak_random (time (NULL) ^
299 GNUNET_CRYPTO_random_u32
300 (GNUNET_CRYPTO_QUALITY_NONCE, UINT32_MAX));
304 void __attribute__ ((destructor))
305 GNUNET_CRYPTO_random_fini ()
307 gcry_set_progress_handler (NULL, NULL);
308 (void) gcry_control (GCRYCTL_CLOSE_RANDOM_DEVICE, 0);
313 /* end of crypto_random.c */