Let's say you're a high-level spook, and you've got a bunch of encrypted intercepts of uncertain origin. Gigabytes and gigabytes of them. Maybe they came with partial keys, maybe they are only 40-bit or 56-bit keyed in the first place. Maybe you have partial keys on some of them (from the "work reduction fields" or whatever on lotus notes for example). You don't have any knowledge that would link a particular one of these with a particular case, but you strongly suspect that somewhere in there are a few dozen that bear on cases you're investigating, and maybe a few dozen more that would be good leads into cases you ought to investigate. You'd like to focus a few dozen Teraflops of processing power on it, but most of your machines are taken up with higher-priority projects pertaining to identifiable cases, or to projects that have better odds of near-term success. What can you do? It should be childs play to set up a "front", as a scientific or charitable organization. Dream up a CPU-intensive task that engages people's imagination or sense of wonder, but which nobody would expect results from anytime soon. Write pages and pages about having written the kind of software you'd need to run to work on that problem -- the Great Idea, the problems, the triumphs and tribulations, the agonizing decisions and occasional design compromises and limitations, and the satisfaction with the end result. All fiction, but hey, this is just a front, right? Now, take your code breaking software and add some pretty graphics to it. Graphics and messages that have to do with the fake project you dreamed up. Arrange it so it runs as a screensaver. Set up a server that breaks the keyspaces and intercepts you need to check into chunks, and let people download chunks to work on and upload results. Set up elaborate tracking stuff that tells how many CPU- hours, how many work units, etc, each contributor has contributed. Hire a bunch of people at the front organization who sincerely believe that all these cycles are expended on the fake project, and let them effusively thank all the people who download and run the software. Explain that you can't release the source, because then people would modify it and your scientific data might be corrupted. It could work.
From the outside, it would look a lot like the SetiAtHome project.
Just a thought. Bear