Password protecting, or hiding the main gallery page

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I am running Gallery 1.5.4. The main feature I want and so far cannot figure out how to do is hiding albums unless you know the URL. As a test I have made one gallery with two albums, say album1 and album2 and configured for not having the navigation link to the main gallery page and also deleted index.php for the main gallery.

So far so good! So, “gallery/album1” takes me to album1 and “gallery/album2” takes me to album2 and “gallery” takes me nowhere. But the problem is when I give a wrong name to an album, for example “gallery/junk” it takes me right to the main gallery page with links and thumbnails for each album in the gallery.

Is it possible to only password-protect the main gallery page or make it not easily accessible to users? Any help highly appreciated.