Guardian: Better privacy and security for Android

I think RogerOdle was referring to the framing given by the container format, which has high regularity. Of course this applies as well to your soopersekrit.odt office document. Known plaintext is a fact of life, even choosen plaintext attacks are to be expected in this context.

Full-disk encryption does not usually compress.

Encrypting only "valuable" data is not a good solution IMO.