static void
mpz_randomize (gcry_mpi_t n, unsigned int nbits, struct GNUNET_HashCode * rnd)
{
struct GNUNET_HashCode hc;
struct GNUNET_HashCode tmp;
int bits_per_hc = sizeof (struct GNUNET_HashCode) * 8;
int cnt;
int i;
GNUNET_assert (nbits > 0);
cnt = (nbits + bits_per_hc - 1) / bits_per_hc;
gcry_mpi_set_ui (n, 0);
tmp = *rnd;
for (i = 0; i < cnt; i++)
{
int j;
if (i > 0)
GNUNET_CRYPTO_hash (&hc, sizeof (struct GNUNET_HashCode), &tmp);
for (j = 0; j < sizeof (struct GNUNET_HashCode) / sizeof (uint32_t); j++)
{
#if HAVE_GCRY_MPI_LSHIFT
gcry_mpi_lshift (n, n, sizeof (uint32_t) * 8);
#else
gcry_mpi_mul_ui (n, n, 1 << (sizeof (uint32_t) * 4));
gcry_mpi_mul_ui (n, n, 1 << (sizeof (uint32_t) * 4));
#endif
gcry_mpi_add_ui (n, n, ntohl (((uint32_t *) & tmp)[j]));
}
hc = tmp;
}
GNUNET_CRYPTO_hash (&hc, sizeof (struct GNUNET_HashCode), rnd);
i = gcry_mpi_get_nbits (n);
while (i > nbits)
gcry_mpi_clear_bit (n, --i);
}
/* Check that left shifting works correctly. */
static void
test_lshift (int pass)
{
static int size_list[] = {1, 31, 32, 63, 64, 65, 70, 0};
int size_idx;
gcry_mpi_t a, b;
char *tmpstr, *result, *result2;
int i;
wherestr = "test_lshift";
show ("checking that lshift works as expected (pass %d)\n", pass);
for (size_idx=0; size_list[size_idx]; size_idx++)
{
a = gcry_mpi_new (0);
b = gcry_mpi_new (0);
/* gcry_mpi_randomize rounds up to full bytes, thus we need to
use gcry_mpi_clear_highbit to fix that. */
gcry_mpi_randomize (a, size_list[size_idx], GCRY_WEAK_RANDOM);
gcry_mpi_clear_highbit (a, size_list[size_idx]);
for (i=0; i < 75; i++)
{
gcry_mpi_lshift (b, a, i);
result = mpi2bitstr_nlz (b);
tmpstr = mpi2bitstr_nlz (a);
result2 = lshiftbitstring (tmpstr, i);
xfree (tmpstr);
if (strcmp (result, result2))
{
show ("got =%s\n", result);
show ("want=%s\n", result2);
fail ("lshift by %d failed\n", i);
}
xfree (result);
xfree (result2);
}
/* Again. This time using in-place operation. */
gcry_mpi_randomize (a, size_list[size_idx], GCRY_WEAK_RANDOM);
gcry_mpi_clear_highbit (a, size_list[size_idx]);
for (i=0; i < 75; i++)
{
gcry_mpi_release (b);
b = gcry_mpi_copy (a);
gcry_mpi_lshift (b, b, i);
result = mpi2bitstr_nlz (b);
tmpstr = mpi2bitstr_nlz (a);
result2 = lshiftbitstring (tmpstr, i);
xfree (tmpstr);
if (strcmp (result, result2))
{
show ("got =%s\n", result);
show ("want=%s\n", result2);
fail ("in-place lshift by %d failed\n", i);
}
xfree (result2);
xfree (result);
}
gcry_mpi_release (b);
gcry_mpi_release (a);
}
}
