Regarding the issue of what to do under Chaum's scheme when someone double- spends a piece of digital cash & their identity is revealed... I don't think it's going to be a serious hindrance in the long term. ... Any credit card company, phone company, or other corporation that does a lot of billing already has staff dedicated solely to that function, with collection agencies providing a second tier of functionality for the tougher cases.

Dr. Cat / Dragon's Eye / New traditions for the next century

Yes, but we would like to steer towards a world where no one you do business with knows or can reconstruct who you are or where you live. "Collection"-- the whole idea of "billing," in fact--is a way of doing business that's rooted in non-privacy. But also it's based on wanting to make transactions easier for people in a world without easy electronic transactions, accounting, budgeting, negotiation, reputations, etc. So maybe with these sorts of things, billing would be unnecessary. Anyway, thinking up variations on offline payment systems is a passtime of mine. Situations where people can't be online with the bank are special cases, so you can make up special-case solutions, like o "Tokens" or gift certificates that you buy in advance, or o Annonymous checks that expire and are refundable if the (specific, annonymous) payees don't cash them in a certain amount of time. Credit as it exists often seems like a trade with the devil of privacy invasion. Jeez, what would the world be like without *credit cards* and *junk mail*!? -fnerd