Ted Ts'oがEXT4で暗号化を実装

http://cpplover.blogspot.jp/2015/04/ted-tsoext4.html
Encryption Support For EXT4 - Phoronix
http://www.phoronix.com/scan.php?page=news_item&px=EXT4-Encryption-Support
ext4 encryption patches
https://lwn.net/Articles/639262/

Android userspace code to use ext4 encryption have been checked into
the public AOSP branch. If all goes well, this feature will hopefully
(my fingers are crossed, but obviously nothing is guaranteed at this
point) be included in the 'M' release of Android.

Android M用として開発されたのか。
http://permalink.gmane.org/gmane.comp.file-systems.ext4/48206
https://docs.google.com/document/d/1IsyQ9DU1gA6NUqS0jF4ni_NTvv-b0HfCkRk47Zkd7W0
残念、このリンクは生きてない。