This will prevent unauthorised visitors to access the admin panel without correct permission.
For example, if you configure the plugin to use key=foo & value=bar, the url for your administrator panel must be: http://myjoomladomain.com/administrator?foo=bar
* You must set this key & value after installation and enable the plug-in just after this initialization.
* The *KEY* MUST CONTAIN *ONLY* letters: A-Z & a-z (NO NUMBERS, NO SIGNS)
* The *VALUE* MUST CONTAIN *ONLY* letters and/or numbers: A-Z, a-z, 0-9 (NO SIGNS).
* After logout from administrator panel, you must re-enter the key&value url to re-enter the administrator panel.
* The key & value settings could be change occasionally.
* If you enabled the plugin without any changing of default values try to login with the next link: http://www.yourdomain.com/administrator?secure_key=secure_value
Thank you so much to the development team.