> Each mailserver could keep a cryptographically verified list, the > list is distributed via some P2P mechanism, and DoS directed at the > 'source' of the service only interrupts updates, and only does so until > the source slips an updated copy of the list to a few peers, and then > the update spreads. Spam is an economic activity and they won't DoS a > source if they know it won't help their situation.
If anyone who attempts to distribute such a list is DoSed to oblivion, people will stop being willing to distribute such a list. Yes, spam is an economic activity, but spammers may engage in long-term planning. You can't keep the list of distributors secret. I'd be very interested in techiques that overcome this problem. I've been looking into tricking existing widely-deployed infrastructures into acting a distributors, but this raises both ethical and technical questions. DS