Secure Double Auction Protocols with Full Privacy Protection

Many researches have been done on the strategies of double auctions, an important class of auction protocols that permit multiple buyers and sellers to trade simultaneously in a market. Some well designed dominant-strategy incentive compatible double auction protocols have been proposed. However, the security and the privacy issues in double auctions are seldom studied in the literatures. In this paper, we propose secure double auction protocols, which achieve full privacy protection of participants. That is, each bid/ask information is always kept secret, even when there is any collusion of participants. It is clear that our suggestion is stronger than other previous work in which assumptions that certain auctioneers never collude are made. To achieve full privacy protection, we employ homomorphic ElGamal encryption and distribute the private key among the all participants. In such a way, all participants jointly compute the outcome of the double auction without revealing any additional bid/ask information. Also, the proposed protocol is publicly verifiable, so that the robustness is assured. The communication and computation complexity of the proposed protocols are analyzed.