"Paul Walker" <paul@black-sun.demon.co.uk> writes:
I submit that if Joe Lunchbox is not spamming, he is unlikely to need to change his habits regarding having his machine available
Mostly unrelated to this, but something's just occurred to me. Probably I'm being really stupid, but ... for the receiving MTA to know that the problem has been processed properly, it would have to know the answer. How does it know what the answer should be?
The same way you know you have the right answer with certain other hard problems -- you choose a problem that's one-way hard. For example: factoring. Factoring a large number is hard. Verifying you have the right answer is easy (you just multiply the factors and see if you've got the right answer). So, just choose from the class of self-verifying problems. OTOH, I still think a micro-payment postage system is a better idea. The sender puts a micro-payment into the mail header to pay the recipient to accept/read the message. For non-spam, the receipient doesn't need to cash the payment (or can just return it to the sander). For spam, the receipient collects the money (thereby costing the spammer real $$$ to send spam, if most receipients actually collect). The only remaining architectural problem is how to handle mailing lits. -derek -- Derek Atkins Computer and Internet Security Consultant derek@ihtfp.com www.ihtfp.com --------------------------------------------------------------------- The Cryptography Mailing List Unsubscribe by sending "unsubscribe cryptography" to majordomo@metzdowd.com