protected function _getAuthVars() {
        if (!$this->_configKey) {
            throw new Garp_Auth_Exception('No config key found in '.__CLASS__.'::_configKey.');
        }
        $config = Zend_Registry::get('config');
        if ($config->auth && $config->auth->adapters && $config->auth->adapters->{$this->_configKey}) {
            return $config->auth->adapters->{$this->_configKey};
        }
        return null;
    }