Can I borrow your device Ok jokes apart, I see your point. It should not only protect the folder but the files in it. I guess, it might be possible to achieve this. For ex, lets take a simple photo viewer app! Assuming the photo viewer app only views files ending with an extension jpg/jpeg/bmp/png/raw/etc. To avoid protected data from being viewable in the photo viewer app, the extensions of those picture files in the to-be-protected folder can be changed to something other what the photo viewer app would understand (say, xyz). And the protector app will remember all these temporary mappings. This app can be protected from being run by a password.