This is to announce 4.2.0.21 SFOS update for Xperia Tama devices: XZ2, XZ2c, and XZ3. Please read release notes and description below before update.
This release introduces support for encryption based on open source implementation. When compared to the official implementation, the open source implementation allows greater flexibility in used encryption passwords, including hardware assisted solutions. When using encryption, you are encouraged to use hardware keystore backed LUKS password which should greatly hinder brute-force attack attempts.
While OTA is possible from the earlier release, it is recommended to reflash the device to enable encryption from the start.
As storage configuration has been altered, note that it is highly recommended to have backup of the data that you have on device.
As always, early adopters please report how it went. For those wishing to be on the safer side, wait till more users would have a chance to test the release.
Edit: Note that after encrypting your device and setting up the system/software, it is recommended to make a copy of encryption recovery password and remove the copy from device. Use System Settings/Encryption (Community) for it.
Edit 26 Sept: bugfix for configs has been released. See Xperia Tama port: 4.2.0.21 release - #16 by rinigus for details.