crypto_random.c File Reference

functions to gather random numbers More...

#include "platform.h"
#include "gnunet_util_lib.h"
#include <gcrypt.h>

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Macros
#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)
#define	RANDOM()   glibc_weak_rand32 ()
#define	SRANDOM(s)   glibc_weak_srand32 (s)
#define	RAND_MAX   0x7fffffff /* Hopefully this is correct */

Functions
void	glibc_weak_srand32 (int32_t s)
int32_t	glibc_weak_rand32 ()
static double	get_weak_random (void)
	Create a cryptographically weak pseudo-random number in the interval of 0 to 1. More...
void	GNUNET_CRYPTO_seed_weak_random (int32_t seed)
	Seed a weak random generator. More...
void	GNUNET_CRYPTO_zero_keys (void *buffer, size_t length)
	Zero out buffer, securely against compiler optimizations. More...
void	GNUNET_CRYPTO_random_block (enum GNUNET_CRYPTO_Quality mode, void *buffer, size_t length)
	Fill block with a random values. More...
uint32_t	GNUNET_CRYPTO_random_u32 (enum GNUNET_CRYPTO_Quality mode, uint32_t i)
	Produce a random unsigned 32-bit number modulo i. More...
unsigned int *	GNUNET_CRYPTO_random_permute (enum GNUNET_CRYPTO_Quality mode, unsigned int n)
	Get an array with a random permutation of the numbers 0...n-1. More...
uint64_t	GNUNET_CRYPTO_random_u64 (enum GNUNET_CRYPTO_Quality mode, uint64_t max)
	Generate a random unsigned 64-bit value. More...
void	GNUNET_CRYPTO_random_timeflake (enum GNUNET_CRYPTO_Quality mode, struct GNUNET_Uuid *uuid)
	Fill UUID with a timeflake pseudo-random value. More...
static void *	w_malloc (size_t n)
	Allocation wrapper for libgcrypt, used to avoid bad locking strategy of libgcrypt implementation. More...
static int	w_check (const void *p)
	Allocation wrapper for libgcrypt, used to avoid bad locking strategy of libgcrypt implementation. More...
void	__attribute__ ((constructor))
	Initialize libgcrypt. More...
void	__attribute__ ((destructor))
	Nicely shut down libgcrypt. More...

Variables
static int32_t	glibc_weak_rand32_state = 1

Detailed Description

functions to gather random numbers

Author

Christian Grothoff

Definition in file crypto_random.c.

Macro Definition Documentation

LOG

#define LOG	(		kind,
			...
	)		GNUNET_log_from (kind, "util-crypto-random", __VA_ARGS__)

Definition at line 32 of file crypto_random.c.

LOG_STRERROR

#define LOG_STRERROR	(		kind,
			syscall
	)		GNUNET_log_from_strerror (kind, "util-crypto-random", syscall)

Definition at line 34 of file crypto_random.c.

RANDOM

#define RANDOM

(

)

glibc_weak_rand32 ()

Definition at line 47 of file crypto_random.c.

SRANDOM

#define SRANDOM

(

s

)

glibc_weak_srand32 (s)

Definition at line 48 of file crypto_random.c.

RAND_MAX

#define RAND_MAX   0x7fffffff /* Hopefully this is correct */

Definition at line 52 of file crypto_random.c.

Function Documentation

glibc_weak_srand32()

void glibc_weak_srand32

(

int32_t

s

)

Definition at line 59 of file crypto_random.c.

{
  glibc_weak_rand32_state = s;
}

References glibc_weak_rand32_state.

glibc_weak_rand32()

int32_t glibc_weak_rand32

(

)

Definition at line 66 of file crypto_random.c.

{
  int32_t val = glibc_weak_rand32_state;
 
  val = ((glibc_weak_rand32_state * 1103515245) + 12345) & 0x7fffffff;
  glibc_weak_rand32_state = val;
  return val;
}

References glibc_weak_rand32_state.

get_weak_random()

static double get_weak_random ( void  )

static

Create a cryptographically weak pseudo-random number in the interval of 0 to 1.

Returns

number between 0 and 1.

Definition at line 84 of file crypto_random.c.

{
  return((double) random () / RAND_MAX);
}

References RAND_MAX.

Referenced by GNUNET_CRYPTO_random_u32(), and GNUNET_CRYPTO_random_u64().

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w_malloc()

static void * w_malloc ( size_t  n )

static

Allocation wrapper for libgcrypt, used to avoid bad locking strategy of libgcrypt implementation.

Definition at line 342 of file crypto_random.c.

{
  return calloc (n, 1);
}

Referenced by __attribute__().

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w_check()

static int w_check ( const void *  p )

static

Allocation wrapper for libgcrypt, used to avoid bad locking strategy of libgcrypt implementation.

Definition at line 353 of file crypto_random.c.

{
  (void) p;
  return 0; /* not secure memory */
}

References p.

Referenced by __attribute__().

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__attribute__() [1/2]

void __attribute__

(

(constructor)

)

Initialize libgcrypt.

Definition at line 363 of file crypto_random.c.

{
  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));
}

References _, GNUNET_assert, GNUNET_CRYPTO_QUALITY_NONCE, GNUNET_CRYPTO_random_u32(), GNUNET_CRYPTO_seed_weak_random(), w_check(), and w_malloc().

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__attribute__() [2/2]

void __attribute__

(

(destructor)

)

Nicely shut down libgcrypt.

Definition at line 402 of file crypto_random.c.

{
  gcry_set_progress_handler (NULL, NULL);
#ifdef GCRYCTL_CLOSE_RANDOM_DEVICE
  (void) gcry_control (GCRYCTL_CLOSE_RANDOM_DEVICE, 0);
#endif
}

Variable Documentation

glibc_weak_rand32_state

int32_t glibc_weak_rand32_state = 1

static

Definition at line 55 of file crypto_random.c.

Referenced by glibc_weak_rand32(), and glibc_weak_srand32().