#include "gnunet_crypto_lib.h"
#include <gcrypt.h>
+/**
+ * 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);
+}
+
+
/**
* Produce a random value.
*
* @return a random value in the interval [0,i[.
*/
uint32_t
-GNUNET_CRYPTO_random_u32 (enum GNUNET_CRYPTO_Quality mode,
- uint32_t i)
+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);
if ((invokeCount++ % 256) == 0)
gcry_fast_random_poll ();
#endif
- gcry_randomize ((unsigned char *) &ret,
- sizeof (uint32_t),
- GCRY_STRONG_RANDOM);
+ ul = UINT32_MAX - (UINT32_MAX % i);
+ do
+ {
+ gcry_randomize ((unsigned char *) &ret,
+ sizeof (uint32_t), GCRY_STRONG_RANDOM);
+ }
+ while (ret >= ul);
return ret % i;
}
else
{
- ret = i * ((double) RANDOM () / RAND_MAX);
+ ret = i * weak_random ();
if (ret >= i)
ret = i - 1;
return ret;
ret = GNUNET_malloc (n * sizeof (unsigned int));
for (i = 0; i < n; i++)
ret[i] = i;
- for (i = 0; i < n; i++)
+ for (i = n - 1; i > 0; i--)
{
- x = GNUNET_CRYPTO_random_u32 (mode, n);
+ x = GNUNET_CRYPTO_random_u32 (mode, i+1);
tmp = ret[x];
ret[x] = ret[i];
ret[i] = tmp;
* @return random 64-bit number
*/
uint64_t
-GNUNET_CRYPTO_random_u64 (enum GNUNET_CRYPTO_Quality mode,
- uint64_t max)
+GNUNET_CRYPTO_random_u64 (enum GNUNET_CRYPTO_Quality mode, uint64_t max)
{
uint64_t ret;
+ uint64_t ul;
GNUNET_assert (max > 0);
if (mode == GNUNET_CRYPTO_QUALITY_STRONG)
{
- gcry_randomize ((unsigned char *) &ret,
- sizeof (uint64_t),
- GCRY_STRONG_RANDOM);
+ ul = UINT64_MAX - (UINT64_MAX % max);
+ do
+ {
+ gcry_randomize ((unsigned char *) &ret,
+ sizeof (uint64_t), GCRY_STRONG_RANDOM);
+ }
+ while (ret >= ul);
return ret % max;
}
else
{
- ret = max * ((double) RANDOM () / RAND_MAX);
+ ret = max * weak_random ();
if (ret >= max)
ret = max - 1;
return ret;
/**
* Initializer
*/
-void __attribute__ ((constructor))
-GNUNET_util_random_init()
+void __attribute__ ((constructor)) GNUNET_util_random_init ()
{
SRANDOM (time (NULL));
}