Howto Set Up LUKS on Turris Omnia

Fire up console and install packages:

opkg update
opkg install cryptsetup mod-crypto-ecb kmod-crypto-iv

You might see this running cryptsetup luksFormat /dev/sdax:

Locking aborted. The locking path /run/cryptsetup is unusable (not a directory or missing). Failed to acquire write device lock.

Just create the directory:

mkdir -p /run/cryptsetup

Now it should work.