Short story?

I'm trying to remember details (author, title) of a short story that I read once. Its main feature, or the one that's standing out in my mind, is the obsessive hacker who studies a target to figure out his password, at which he only has one guess. The zinger is that the very security concious target has selected that password as a booby trap, and there's a second password which our hacker doesn't have. Does this ring a bell for anyone? Adam -- "It is seldom that liberty of any kind is lost all at once." -Hume