private function timestampHasExpired($timestamp)
{
$year = substr($timestamp, 0, 4);
$month = substr($timestamp, 5, 2);
$day = substr($timestamp, 8, 2);
$hour = substr($timestamp, 11, 2);
$minute = substr($timestamp, 14, 2);
$second = substr($timestamp, 17, 2);
$timestamp = gmmktime($hour, $minute, $second, $month, $day, $year);
$diff = time() - $timestamp;
if ($diff > $this->maxDiff || $diff < -$this->maxDiff) {
return true;
}
return false;
}