Interesting idea, I like the "as much certainty as you want" with the probability.

Why can't this be parallelized? Sure you have to work on one key at a time because they are sequential, but 1000 machines can be cracking that one key. Every key cracked would be distributed and the cluster would start in on the next.

It's a little more complicated, but I'm not seeing how it's really any less parallelizeable.