Re: Spoiling digital cash
-- On 10 Dec 2001, at 16:16, [EMAIL PROTECTED] wrote: An idea just popped into my head, I was wondering if anyone had thought of this before. Most likely someone has, and has either proven the idea is impossible or has figured out how to do it. Th idea is, when buying some good or service with digital cash, the customer first forwards the cash to the vendor in some transformed way such that the vendor can't yet spend it, but can verify that it is good cash of the correct amount, and that the customer will no longer be able to spend it. The idea is, if the vendor follows through on his side, the customer will supply the additional information the vendor will need to redeem the cash. The customer can still rip the vendor off by refusing to do so, but he has no incentive, the money's already gone for him. Conversely, an unscrupulous vendor could in principle trick a customer into throwing away money on nothing, but he would gain no profit in doing so. Vendor creates and blinds some tokens. Asks buyer to have them signed by money issuer. Money issuer signs them, and issues declaration that they have been signed. Buyer gives vendor the declaration, but not signatures. After delivery, gives signatures. --digsig James A. Donald 6YeGpsZR+nOTh/cGwvITnSR3TdzclVpR0+pr3YYQdkG vNpp48iuJszNXUqQ3P9/e7GUOEcHXoIDo33hfuKd 4xRG9QbdRJM31N1Lt+bhH55JK5VQWVorCJq0o7gAp
Re: Spoiling digital cash
At 09:48 PM 12/10/01 -0600, Jim Choate wrote: On Tue, 11 Dec 2001, Anonymous wrote: To rip the coin, the passenger gives the taxi driver t = s^e1, along with x. The driver can verify that t^e2 = s^(e1*e2) = s^e1 = x mod n which tells him that it is a real coin. He also sends (t, x) to the bank, which verifies that no such x has been spent before (no double spending) and also stores x as a ripped coin such that only the driver can spend it. Who pays for all this checking? Not only does this require the taxi driver to have a considerable store of computational and algorithmic 'equipment' but he's also got to have a comm channel to the bank. This don't sound cheap to execute at all... Oh, you mean like the $5 charge that Mastercard/Visa charge merchants... this *corroborates* the stuff Hettinga has been saying about it being cheaper to use certain kinds of payment than others.
Re: Spoiling digital cash
On Mon, 10 Dec 2001, David Honig wrote: this *corroborates* the stuff Hettinga has been saying about it being cheaper to use certain kinds of payment than others. Actually Hettinga's observation is rather obvious. The concept that all exchanges will cost the same is rather self-destructing. Nothing newe there. -- Day by day the Penguins are making me lose my mind. Bumper Sticker The Armadillo Group ,::;::-. James Choate Austin, Tx /:'/ ``::/|/ [EMAIL PROTECTED] www.ssz.com.', `/( e\ 512-451-7087 -~~mm-'`-```-mm --'-
