FreeNAS is the first and only open source project to offer encryption on ZFS volumes! A full-volume encryption option is available during volume creation, providing industry standard AES-XTS encryption which can be hardware-accelerated (when the processor has AES-NI capability).
Encrypted volumes can only be read by FreeNAS systems in possession of the master key for that volume. The user can optionally create a passphrase to add extra protection for their system against loss or theft.
Encryption allows for confidence when retiring and recycling hard drives because the drives no longer need to be wiped provided the master keys are obliterated.
(Download FreeNAS 11)