protected function getAuth(array $config)
	{
		if (isset($config['key']) && trim($config['key']) != '')
		{
			return array('key' => $config['key'], 'keyphrase' => $config['keyphrase']);
		}
		elseif (isset($config['keytext']) && trim($config['keytext']) != '')
		{
			return array('keytext' => $config['keytext']);
		}
		elseif (isset($config['password']))
		{
			return array('password' => $config['password']);
		}

		throw new \InvalidArgumentException('Password / key is required.');
	}