public static function hash_password($password) {
	$exception = bootstrap::get_library('exception');
	
	if (mb_strlen($password) < self::MINIMUM_LENGTH) {
		throw new $exception('passwords need a minimum length of '.self::MINIMUM_LENGTH);
	}
	
	$hash = password_hash($password, PASSWORD_DEFAULT);
	if (empty($hash)) {
		throw new $exception('unable to hash password');
	}
	
	return $hash;
}