protected function verifyIV(){
		$iv_size = mcrypt_get_iv_size(self::$crypt_cipher,self::$crypt_mode);
		//verify we have a key before starting
		if(!isset($this->iv) || is_null($this->iv)){
			throw new Exception('No IV key defined in config');
		}
		if(strlen(base64_decode($this->iv)) < $iv_size){
			throw new Exception('Encryption IV is too shorted, required length: '.$iv_size);
		}
		return true;
	}