In <199610140530.WAA17735@crypt>, on 10/13/96 at 10:30 PM, Hal Finney <hal@rain.org> said:
The "blinded identities" problem is one of the oldest that we have discussed here (although not much recently, of course!). It is basically similar to what cryptographers call "blinded credentials" and is closely related to electronic cash, as Michael Froomkin's example from Stefan Brands points out. I posted an idea a few years ago for how to use the technique to solve the related problem of remailer abuse.
A simple way to approximate what you want is to use a standard blinded signature exactly as is done with David Chaum's DigiCash. The customer comes to you and presents some proof of identity. This may be in person via standard paper documents, or on-line via some cryptographic credential as you suggested. You make a list of all of your customers, and make sure that this customer is new, someone you haven't seen before.
Hmmmm... I am at a loss as why the customers identity needs to be know at all? What does it matter if I am a new customer or not? I don't see why we couldn't have anonymous prepaid credit-cards similiar to the prepaid calling cards available now. You pop down to the local bank here's $500 cash, they give you your card, when you have used up your $500 you throw it away. Of cource the issuer of the card would charge some fee for the service, say $1 on every $100, maybe more maybe less the market will decide that. :) No one need know who I am or what I am purchasing. Much simpler to implement, no id verification, no blinded credentials, Just treat it like any other credit card. KISS - Keep It Simple Stupid :) -- ----------------------------------------------------------- William H. Geiger III http://www.amaranth.com/~whgiii Geiger Consulting WebExplorer & Java Enhanced!!! Cooking With Warp 4.0 Author of PGPMR2 - PGP Front End for MR/2 Ice Look for MR/2 Tips & Rexx Scripts Get Work Place Shell for Windows!! PGP & MR/2 the only way for secure e-mail. Finger whgiii@amaranth.com for PGP Key and other info ----------------------------------------------------------- *MR/2 ICE: Windows: Just another pane in the glass.