Ok, so I've been debugging the last update of my system and found this warning running journalctl -b -p warning:systemd-cryptsetup: Key file <location> is world-readable. This is not a good idea!Generally I understand what is the matter and that it's bad. Though I don't know how to fix this properly without ruining my boot.Then comes the question: what permissions do I have to set for that file to make  my system working correctly while removing the warning? Is 600 ok? Or do some system groups also need an access to this file?
systemd-cryptsetup key file readable warning
systemd;encryption;disk encryption
Ok, so indeed 600 permissions are considered a good and the only good practice for securing a key file (source: archwiki).Also the tricky thing here is that when the kernel is updated initramfs generation procedure resets the key file permission to 644 which basically allows to dump it's content. That means that after each kernel update the right permission set should be restored by user. 