Enabling ZFS encryption on ubuntu 23.10

readme

Ubuntu 23.10 lets you select the advanced option of using ZFS, but not encrypting it.

#assuming you want to use zstd compression, if not remove the compress=zstd bits, as it defaults to lz4
#This doesn't encrypt the boot pool.
#ROOT is the root zfs dataset.

1) Install ubuntu 23.10 as normal, select the advanced/experimental options when installing and select ZFS
2) Once the install is done, reboot back into the installer (via USB/DVD/etc)
3) "Try ubuntu" and open a terminal, then sudo -i to root
4) zpool import -f rpool
5) zfs list (get rpool/ROOT/ubuntu_<x>, where <x> will be some random numbers/letter we need this for later)
6) zfs snapshot -r rpool/ROOT@copy
7) zfs send -R rpool/ROOT@copy | zfs receive rpool/copyroot
8) zfs destroy -r rpool/ROOT
9) zfs create -o encryption=on -o keyformat=passphrase -o compress=zstd rpool/ROOT
10) Enter passphrase twice
11) zfs send -R rpool/copyroot/ubuntu_<x>@copy | zfs receive -o encryption=on -o compress=zstd rpool/ROOT/ubuntu_<x>
12) zfs destroy -r rpool/copyroot
13) zfs destroy -r rpool/ROOT/ubuntu_<x>@copy
14) zpool export rpool
15) reboot

For some reason this first boot gets stuck on the UEFI spinning screen, wait a few minutes then reset the machine and it will boot properly