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