An anonymous and failure resilient fair-exchange e-commerce protocol

In an electronic commerce environment, the merchant and the customer are unlikely to trust each other. This problem has motivated researchers to propose fair-exchange protocols based on using an on-line trusted third party; the third party receives the items being exchanged from the customer and the merchant and then forwards it to the other party in a fair manner. However, the third party is a source of bottleneck for these protocols. Not only is the performance of the third party an issue, but also its vulnerability to denial of service attacks. In this paper, we propose an optimistic protocol in which the trusted third party is invoked only if any party misbehaves or prematurely aborts. The protocol achieves fairness and dispute resolution is performed automatically within the scope of the protocol. We show how we can distribute the function of the trusted third party across several third parties; this increases the robustness of the protocol. Additionally, we show how by adopting a payment mechanism based on electronic cash, we provide anonymity to the customer's transactions.