/*
This file is part of GNUnet. Copyright (C) 2001-2014 Christian Grothoff
(and other contributing authors)
GNUnet is free software: you can redistribute it and/or modify it
under the terms of the GNU Affero General Public License as published
by the Free Software Foundation, either version 3 of the License,
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
Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License
along with this program. If not, see .
SPDX-License-Identifier: AGPL3.0-or-later
*/
/**
* @file util/crypto_random.c
* @brief functions to gather random numbers
* @author Christian Grothoff
*/
#include "platform.h"
#include "gnunet_crypto_lib.h"
#include
#define LOG(kind, ...) GNUNET_log_from (kind, "util-crypto-random", __VA_ARGS__)
#define LOG_STRERROR(kind, syscall) \
GNUNET_log_from_strerror (kind, "util-crypto-random", syscall)
/* TODO: ndurner, move this to plibc? */
/* The code is derived from glibc, obviously */
#if ! HAVE_RANDOM || ! HAVE_SRANDOM
#ifdef RANDOM
#undef RANDOM
#endif
#ifdef SRANDOM
#undef SRANDOM
#endif
#define RANDOM() glibc_weak_rand32 ()
#define SRANDOM(s) glibc_weak_srand32 (s)
#if defined(RAND_MAX)
#undef RAND_MAX
#endif
#define RAND_MAX 0x7fffffff /* Hopefully this is correct */
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
get_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);
}
/**
* @ingroup crypto
* Zero out @a buffer, securely against compiler optimizations.
* Used to delete key material.
*
* @param buffer the buffer to zap
* @param length buffer length
*/
void
GNUNET_CRYPTO_zero_keys (void *buffer, size_t length)
{
#if HAVE_MEMSET_S
memset_s (buffer, length, 0, length);
#elif HAVE_EXPLICIT_BZERO
explicit_bzero (buffer, length);
#else
volatile unsigned char *p = buffer;
while (length--)
*p++ = 0;
#endif
}
/**
* @ingroup crypto
* Fill block with a random values.
*
* @param mode desired quality of the random number
* @param buffer the buffer to fill
* @param length buffer length
*/
void
GNUNET_CRYPTO_random_block (enum GNUNET_CRYPTO_Quality mode,
void *buffer,
size_t length)
{
#ifdef gcry_fast_random_poll
static unsigned int invokeCount;
#endif
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
gcry_randomize (buffer, length, GCRY_STRONG_RANDOM);
return;
case GNUNET_CRYPTO_QUALITY_NONCE:
gcry_create_nonce (buffer, length);
return;
case GNUNET_CRYPTO_QUALITY_WEAK:
/* 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
gcry_randomize (buffer, length, GCRY_WEAK_RANDOM);
return;
default:
GNUNET_assert (0);
}
}
/**
* Produce a random unsigned 32-bit number modulo @a i.
*
* @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 * get_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;
}
/**
* Generate random unsigned 64-bit value.
*
* @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 * get_weak_random ();
if (ret >= max)
ret = max - 1;
return ret;
default:
GNUNET_assert (0);
}
return 0;
}
/**
* Allocation wrapper for libgcrypt, used to avoid bad locking
* strategy of libgcrypt implementation.
*/
static void *
w_malloc (size_t n)
{
return calloc (n, 1);
}
/**
* Allocation wrapper for libgcrypt, used to avoid bad locking
* strategy of libgcrypt implementation.
*/
static int
w_check (const void *p)
{
(void) p;
return 0; /* not secure memory */
}
/**
* Initialize libgcrypt.
*/
void __attribute__ ((constructor))
GNUNET_CRYPTO_random_init ()
{
gcry_error_t rc;
if (! gcry_check_version (NEED_LIBGCRYPT_VERSION))
{
fprintf (
stderr,
_ ("libgcrypt has not the expected version (version %s is required).\n"),
NEED_LIBGCRYPT_VERSION);
GNUNET_assert (0);
}
/* set custom allocators */
gcry_set_allocation_handler (&w_malloc, &w_malloc, &w_check, &realloc, &free);
/* Disable use of secure memory */
if ((rc = gcry_control (GCRYCTL_DISABLE_SECMEM, 0)))
fprintf (stderr,
"Failed to set libgcrypt option %s: %s\n",
"DISABLE_SECMEM",
gcry_strerror (rc));
/* Otherwise gnunet-ecc takes forever to complete, besides
we are fine with "just" using GCRY_STRONG_RANDOM */
if ((rc = gcry_control (GCRYCTL_ENABLE_QUICK_RANDOM, 0)))
fprintf (stderr,
"Failed to set libgcrypt option %s: %s\n",
"ENABLE_QUICK_RANDOM",
gcry_strerror (rc));
gcry_control (GCRYCTL_INITIALIZATION_FINISHED, 0);
gcry_fast_random_poll ();
GNUNET_CRYPTO_seed_weak_random (
time (NULL)
^ GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_NONCE, UINT32_MAX));
}
/**
* Nicely shut down libgcrypt.
*/
void __attribute__ ((destructor))
GNUNET_CRYPTO_random_fini ()
{
gcry_set_progress_handler (NULL, NULL);
#ifdef GCRYCTL_CLOSE_RANDOM_DEVICE
(void) gcry_control (GCRYCTL_CLOSE_RANDOM_DEVICE, 0);
#endif
}
/* end of crypto_random.c */