[ickyfehmleh]

How are you going to hide the files without any random application knowing about them and accessing them out from under you?

You could add a '.' before the directory name, but any app can read directories and show dot-files (eg ASTRO has a setting to show/hide "hidden" files).

You could use a strange directory name but we see how well that worked for Google's lolworthy attempt at preventing software piracy by placing "protected" applications in a directory called "app-private", which is sure to not draw any attention to it whatsoever.

You're going to have to involve some sort of encryption, like PGP maybe. I'm sure you can find an open-source Java implementation of PGP.

Oh, and by "hiding" the contacts you're going to screw up Google's contacts Sync, so you'll want to reimplement that. Untold other applications will see no contacts since they're now "hidden" behind your application. I don't know about you, but I kinda rely on Android's ability to share data with other applications via intents and content providers, so your idea diminishes a lot of value and takes away from the "wow" factor of Android... so you'll want to reimplement that. Maybe you could insist that every other developer update their applications to access contacts and media through your new method and not the tired old Android way of doing things.

Good luck, let me know how it goes.