/****************
* Returns: true if this may be a prime
*/
static int
check_prime( MPI prime, MPI val_2 )
{
int i;
unsigned x;
int count=0;
/* check against small primes */
for(i=0; (x = small_prime_numbers[i]); i++ ) {
if( mpi_divisible_ui( prime, x ) )
return 0;
}
/* a quick fermat test */
{
MPI result = mpi_alloc_like( prime );
MPI pminus1 = mpi_alloc_like( prime );
mpi_sub_ui( pminus1, prime, 1);
mpi_powm( result, val_2, pminus1, prime );
mpi_free( pminus1 );
if( mpi_cmp_ui( result, 1 ) ) { /* if composite */
mpi_free( result );
progress('.');
return 0;
}
mpi_free( result );
}
/* perform stronger tests */
if( is_prime(prime, 5, &count ) )
return 1; /* is probably a prime */
progress('.');
return 0;
}
/****************
* Returns: true if this may be a prime
*/
static int
check_prime( gcry_mpi_t prime, gcry_mpi_t val_2,
gcry_prime_check_func_t cb_func, void *cb_arg)
{
int i;
unsigned int x;
unsigned int count=0;
/* Check against small primes. */
for (i=0; (x = small_prime_numbers[i]); i++ )
{
if ( mpi_divisible_ui( prime, x ) )
return 0;
}
/* A quick Fermat test. */
{
gcry_mpi_t result = mpi_alloc_like( prime );
gcry_mpi_t pminus1 = mpi_alloc_like( prime );
mpi_sub_ui( pminus1, prime, 1);
gcry_mpi_powm( result, val_2, pminus1, prime );
mpi_free( pminus1 );
if ( mpi_cmp_ui( result, 1 ) )
{
/* Is composite. */
mpi_free( result );
progress('.');
return 0;
}
mpi_free( result );
}
if (!cb_func || cb_func (cb_arg, GCRY_PRIME_CHECK_AT_MAYBE_PRIME, prime))
{
/* Perform stronger tests. */
if ( is_prime( prime, 5, &count ) )
{
if (!cb_func
|| cb_func (cb_arg, GCRY_PRIME_CHECK_AT_GOT_PRIME, prime))
return 1; /* Probably a prime. */
}
}
progress('.');
return 0;
}
