[kijin]

> For instance, scanning anything but your right index finger might force a password-only lock. Scanning a pinky (or some other fingerprint / combination of fingerprints) might cause the phone to factory reset, or unlock and trigger deletion a specified portion of user data.

That's not plausible deniability, it's willful destruction of evidence. It's going to look extremely suspicious when your phone suddenly asks for a second factor or gets factory reset. This will only invite more liberal use of the rubber hose.

True plausible deniability is completely different. Your phone should unlock and expose all sorts of insignificant-but-realistic data to make it look like you've been using it all the time. This can't be done convincingly with a hidden O/S unless you use the hidden O/S every day, which is impractical for most people.

What we need is software that allows us to mark certain bits of data (files, messages, call history, apps) as "safe to expose" (whitelist mode) or "must hide" (blacklist mode) with little more than a couple of taps/clicks during normal usage. Not just hidden at the application level, but gone from the underlying filesystem as well. Any ideas for an encrypted, possibly layered filesystem with two or more keys that expose different subsets of files, leaving the rest indistinguishable from empty space?