ZFS Native Encryption by Tom Caputi

On the contrary, it makes it suitable for file systems! File systems are not block devices, they are data structures on top of block devices — it's the job of these data structures to keep stuff, such as data, inodes, and... keys, and IVs, and MACs, checksums, etc. TFS uses Speck in XEX mode (edit: I just realized you're the author, so you already know that :). tptacek wrote a nice post about it: link and I quote: "If you’re encrypting a filesystem and not disk blocks, still don’t use XTS! Filesystems have format-awareness and flexibility. Filesystems can do a much better job of encrypting a disk than simulated hardware encryption can." Edit: check out this presentation on how encryption was bolted on ZFS: this video (slides: link ) It's not perfect, but it provides data authentication by reusing checksum fields for storing MACs. Edit 2: also check out bcachefs encryption design doc: link (also not perfect, but uses proper AEAD — ChaCha20-Poly1305. I sent some questions and suggestions to the author, but received no reply :/)

The problem is that a stream cipher is going to have some per-object uniqueness (a salt, IV, etc.), so by design even if you feed it related input blocks you will get different output blocks. This is, of course, antithetical to deduplication: so you need to check/store the hash of the input before it goes through the cipher. The presentation about ZFS' native encryption[1] covers many of these sorts of trade-offs necessary to do full-disk encryption at scale. [1]: this video