Re: Recovery of LUKS keyslot during PBKDF phase of overwrite ChangeKey possible?

I should have included these questions:

Could I just terminate the systemd process when it hasn't actually 
computed the key yet? More specifically, when does cryptsetup actually 
start overwriting the keyslot when the --keyslot parameter is used? Is 
there some overwriting already before it is done computing or only 
after? If only after, then the keyslot should not yet have been harmed 
as it's not done with the iterations, right?

Thank you.