How to Break and Repair a “Provably Secure” Untraceable Payment System
On Crypto’ 88, an untraceable payment system with provable security against abuse by individuals was presented by Damgård. We show how to break the untraceability of that system completely.
Next, an improved version of the system is presented. We also augment the system by security for the individuals against loss of money, and we introduce the possibility of receipts for payments. Finally, whereas all this concerned an on-line system, we present a similar construction for untraceable electronic cash.