C.5.1. Set a randomly generated key as an additional way to access an encrypted block device
These sections are about generating keys and adding keys.
This will generate a 256-bit key in the file $HOME/keyfile.
dd if=/dev/urandom of=$HOME/keyfile bs=32 count=1
chmod 600 $HOME/keyfile
C.5.1.2. Add the key to an available keyslot on the encrypted device
cryptsetup luksAddKey <device> ~/keyfile
