public function validateData($data,$key=null)
	{
		if (!is_string($data))
			return false;

		$len=$this->strlen($this->computeHMAC('test'));
		if($this->strlen($data)>=$len)
		{
			$hmac=$this->substr($data,0,$len);
			$data2=$this->substr($data,$len,$this->strlen($data));
			return $this->compareString($hmac,$this->computeHMAC($data2,$key))?$data2:false;
		}
		else
			return false;
	}