Is it possible to invalidate an existing tarsnap key so it cannot be used in future. I have a key for a decommissioned machine so it's no longer needed and hypothetically it could be used for DoS attack (by creating bogus archives and draining the account funds). Obviously this is impossible unless the key leaks somehow, but operational paranoia would suggest invalidating it would be a good idea.
-- All network cabling aspires to the condition of macramé.
