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Diffstat (limited to 'src/util/crypto_random.c')
| -rw-r--r-- | src/util/crypto_random.c | 334 |
1 files changed, 334 insertions, 0 deletions
diff --git a/src/util/crypto_random.c b/src/util/crypto_random.c new file mode 100644 index 0000000..25226a3 --- /dev/null +++ b/src/util/crypto_random.c @@ -0,0 +1,334 @@ +/* + This file is part of GNUnet. + (C) 2001, 2002, 2003, 2004, 2005, 2006 Christian Grothoff (and other contributing authors) + + GNUnet is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published + by the Free Software Foundation; either version 2, or (at your + option) any later version. + + GNUnet is distributed in the hope that it will be useful, but + WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + General Public License for more details. + + You should have received a copy of the GNU General Public License + along with GNUnet; see the file COPYING. If not, write to the + Free Software Foundation, Inc., 59 Temple Place - Suite 330, + Boston, MA 02111-1307, USA. + +*/ + +/** + * @file util/crypto_random.c + * @brief functions to gather random numbers + * @author Christian Grothoff + */ +#include "platform.h" +#include "gnunet_common.h" +#include "gnunet_crypto_lib.h" +#include "gnunet_os_lib.h" +#include <gcrypt.h> + +#define LOG(kind,...) GNUNET_log_from (kind, "util", __VA_ARGS__) + +#define LOG_STRERROR(kind,syscall) GNUNET_log_from_strerror (kind, "util", syscall) + +/* TODO: ndurner, move this to plibc? */ +/* The code is derived from glibc, obviously */ +#if MINGW +#ifdef RANDOM +#undef RANDOM +#endif +#ifdef SRANDOM +#undef SRANDOM +#endif +#define RANDOM() glibc_weak_rand32() +#define SRANDOM(s) glibc_weak_srand32(s) +static int32_t glibc_weak_rand32_state = 1; + +void +glibc_weak_srand32 (int32_t s) +{ + glibc_weak_rand32_state = s; +} + +int32_t +glibc_weak_rand32 () +{ + int32_t val = glibc_weak_rand32_state; + + val = ((glibc_weak_rand32_state * 1103515245) + 12345) & 0x7fffffff; + glibc_weak_rand32_state = val; + return val; +} +#endif + +/** + * Create a cryptographically weak pseudo-random number in the interval of 0 to 1. + * + * @return number between 0 and 1. + */ +static double +weak_random () +{ + return ((double) RANDOM () / RAND_MAX); +} + +/** + * Seed a weak random generator. Only GNUNET_CRYPTO_QUALITY_WEAK-mode generator + * can be seeded. + * + * @param seed the seed to use + */ +void +GNUNET_CRYPTO_seed_weak_random (int32_t seed) +{ + SRANDOM (seed); +} + +/** + * Produce a random value. + * + * @param mode desired quality of the random number + * @param i the upper limit (exclusive) for the random number + * @return a random value in the interval [0,i[. + */ +uint32_t +GNUNET_CRYPTO_random_u32 (enum GNUNET_CRYPTO_Quality mode, uint32_t i) +{ +#ifdef gcry_fast_random_poll + static unsigned int invokeCount; +#endif + uint32_t ret; + uint32_t ul; + + GNUNET_assert (i > 0); + + switch (mode) + { + case GNUNET_CRYPTO_QUALITY_STRONG: + /* see http://lists.gnupg.org/pipermail/gcrypt-devel/2004-May/000613.html */ +#ifdef gcry_fast_random_poll + if ((invokeCount++ % 256) == 0) + gcry_fast_random_poll (); +#endif + ul = UINT32_MAX - (UINT32_MAX % i); + do + { + gcry_randomize ((unsigned char *) &ret, sizeof (uint32_t), + GCRY_STRONG_RANDOM); + } + while (ret >= ul); + return ret % i; + case GNUNET_CRYPTO_QUALITY_NONCE: + ul = UINT32_MAX - (UINT32_MAX % i); + do + { + gcry_create_nonce (&ret, sizeof (ret)); + } + while (ret >= ul); + return ret % i; + case GNUNET_CRYPTO_QUALITY_WEAK: + ret = i * weak_random (); + if (ret >= i) + ret = i - 1; + return ret; + default: + GNUNET_assert (0); + } + return 0; +} + + +/** + * Get an array with a random permutation of the + * numbers 0...n-1. + * @param mode GNUNET_RANDOM_QUALITY_STRONG if the strong (but expensive) + * PRNG should be used, GNUNET_RANDOM_QUALITY_WEAK otherwise + * @param n the size of the array + * @return the permutation array (allocated from heap) + */ +unsigned int * +GNUNET_CRYPTO_random_permute (enum GNUNET_CRYPTO_Quality mode, unsigned int n) +{ + unsigned int *ret; + unsigned int i; + unsigned int tmp; + uint32_t x; + + GNUNET_assert (n > 0); + ret = GNUNET_malloc (n * sizeof (unsigned int)); + for (i = 0; i < n; i++) + ret[i] = i; + for (i = n - 1; i > 0; i--) + { + x = GNUNET_CRYPTO_random_u32 (mode, i + 1); + tmp = ret[x]; + ret[x] = ret[i]; + ret[i] = tmp; + } + return ret; +} + +/** + * Random on unsigned 64-bit values. + * + * + * @param mode desired quality of the random number + * @param max value returned will be in range [0,max) (exclusive) + * @return random 64-bit number + */ +uint64_t +GNUNET_CRYPTO_random_u64 (enum GNUNET_CRYPTO_Quality mode, uint64_t max) +{ + uint64_t ret; + uint64_t ul; + + GNUNET_assert (max > 0); + switch (mode) + { + case GNUNET_CRYPTO_QUALITY_STRONG: + ul = UINT64_MAX - (UINT64_MAX % max); + do + { + gcry_randomize ((unsigned char *) &ret, sizeof (uint64_t), + GCRY_STRONG_RANDOM); + } + while (ret >= ul); + return ret % max; + case GNUNET_CRYPTO_QUALITY_NONCE: + ul = UINT64_MAX - (UINT64_MAX % max); + do + { + gcry_create_nonce (&ret, sizeof (ret)); + } + while (ret >= ul); + + return ret % max; + case GNUNET_CRYPTO_QUALITY_WEAK: + ret = max * weak_random (); + if (ret >= max) + ret = max - 1; + return ret; + default: + GNUNET_assert (0); + } + return 0; +} + +/** + * This function should only be called in testcases + * where strong entropy gathering is not desired + * (for example, for hostkey generation). + */ +void +GNUNET_CRYPTO_random_disable_entropy_gathering () +{ + gcry_control (GCRYCTL_ENABLE_QUICK_RANDOM, 0); +} + + +/** + * Process ID of the "find" process that we use for + * entropy gathering. + */ +static struct GNUNET_OS_Process *genproc; + +/** + * Function called by libgcrypt whenever we are + * blocked gathering entropy. + */ +static void +entropy_generator (void *cls, const char *what, int printchar, int current, + int total) +{ + unsigned long code; + enum GNUNET_OS_ProcessStatusType type; + int ret; + + if (0 != strcmp (what, "need_entropy")) + return; + if (current == total) + { + if (genproc != NULL) + { + if (0 != GNUNET_OS_process_kill (genproc, SIGTERM)) + LOG_STRERROR (GNUNET_ERROR_TYPE_ERROR, "kill"); + GNUNET_break (GNUNET_OK == GNUNET_OS_process_wait (genproc)); + GNUNET_OS_process_close (genproc); + genproc = NULL; + } + return; + } + if (genproc != NULL) + { + ret = GNUNET_OS_process_status (genproc, &type, &code); + if (ret == GNUNET_NO) + return; /* still running */ + if (ret == GNUNET_SYSERR) + { + GNUNET_break (0); + return; + } + if (0 != GNUNET_OS_process_kill (genproc, SIGTERM)) + LOG_STRERROR (GNUNET_ERROR_TYPE_ERROR, "kill"); + GNUNET_break (GNUNET_OK == GNUNET_OS_process_wait (genproc)); + GNUNET_OS_process_close (genproc); + genproc = NULL; + } + LOG (GNUNET_ERROR_TYPE_INFO, _("Starting `%s' process to generate entropy\n"), + "find"); + genproc = + GNUNET_OS_start_process (GNUNET_NO, + NULL, NULL, "sh", "sh", "-c", + "exec find / -mount -type f -exec cp {} /dev/null \\; 2>/dev/null", + NULL); +} + + +static void +killfind () +{ + if (genproc != NULL) + { + GNUNET_OS_process_kill (genproc, SIGKILL); + GNUNET_OS_process_close (genproc); + genproc = NULL; + } +} + + +void __attribute__ ((constructor)) GNUNET_CRYPTO_random_init () +{ + gcry_control (GCRYCTL_DISABLE_SECMEM, 0); + if (!gcry_check_version (GCRYPT_VERSION)) + { + FPRINTF (stderr, + _ + ("libgcrypt has not the expected version (version %s is required).\n"), + GCRYPT_VERSION); + GNUNET_abort (); + } +#ifdef GCRYCTL_INITIALIZATION_FINISHED + gcry_control (GCRYCTL_INITIALIZATION_FINISHED, 0); +#endif +#ifdef gcry_fast_random_poll + gcry_fast_random_poll (); +#endif + gcry_set_progress_handler (&entropy_generator, NULL); + atexit (&killfind); + GNUNET_CRYPTO_seed_weak_random (time (NULL) ^ + GNUNET_CRYPTO_random_u32 + (GNUNET_CRYPTO_QUALITY_NONCE, UINT32_MAX)); +} + + +void __attribute__ ((destructor)) GNUNET_CRYPTO_random_fini () +{ + gcry_set_progress_handler (NULL, NULL); +} + + + +/* end of crypto_random.c */ |