Protocol for irreversible off-line transactions in anonymous electronic currency exchange
Marek R. Ogiela, Piotr Sułkowski · Soft Computing · 2014
This paper presents an improvement to the well-known protocol by David Chaum for anonymous currency exchange. We show its vulnerability to serious frauds by both the client and the seller, after an electronic coin is spent at least twice. In this case, the system cannot successfully determine how many times the client spent the coin and how many times the seller faked the transaction. Therefore, the bank is not able to charge the real abuser. This limitation leads to the conclusion that the original system cannot be securely used for irreversible off-line transactions. In this paper, we show the gist of the problem and propose an improved system based on its original off-line version that allows this vulnerability to be overcome.