Reducing server trust in private proxy auctions

Abstract

We investigate proxy auctions, an auction model which is proving very successful for on-line businesses (e.g., [9]), where a trusted server manages bids from clients by continuously updating the current price of the item and the currently winning bid as well as keeping private the winning client's maximum bid. We propose techniques for reducing the trust in the server by defining and achieving a security property, called server integrity. Informally, this property protects clients from a novel and large class of attacks from a corrupted server by allowing them to verify the correctness of updates to the current price and the currently winning bid. Our new auction scheme achieves server integrity and satisfies two important properties that are not enjoyed by previous work in the literature: it has minimal interaction, and only requires a single trusted server. While the privacy property of our scheme holds under a standard intractability assumption, the server integrity property holds unconditionally. © Springer-Verlag 2004.