In Steam Kernel, you can now chose to apply filesystem encryption to any of the 3 main partitions (cache, data, dbdata). The password can be entered using the screen by one, or multiple Swypes (up to 255 elements). Each swype creates a word, and words will be separated by "_". This mechanism was invented, as with this one can potentially achieve a good-enough entropy (although I'm not a cryptoanalyst), than by for example a simple PIN code entry box.
If you worry about speed, quadrant scores are around 1400 if using ext4+crypt, so they're still better, than stock rfs. I can't say much about battery life yet.
This feature is beta however, so don't rely valuable data to it yet, as it hasn't been throughly tested yet. (ancrpytion should be fine, I'm actually worried about data corruption).
The way to secure android is not yet finished however. I'm trying to find a way to secure adb, even if it's running root mode. (as running adb in root mode is good for debugging, but bad for security).
Questions on this topic is welcome.