Native Encryption for ZFS on FreeBSD CFT

[Sean Fagan]

On Aug 22, 2018, at 12:35 PM, Alan Somers <asomers at freebsd.org> wrote:
> Only encrypting L0 blocks also leaks a lot of information.  That means that, if encryption is set to anything but "off", watermarking attacks will still be possible based on the size and sparsity of a file.  Because I believe that with any encryption mode, ZFS turns continuous runs of zeros into holes.  And I don't see anything in zio_crypt.c that addresses that.

I’m not sure about that.  However, with compression=off,

	dd if=/dev/zero of=bigfile bs=1m count=1024

results in a file that is 1565148 blocks (of 128k bytes), which supports your statement.

With compression=on, it creates a 1 block file.

Sean.