An Anonymous Bidding Protocol without Any Reliable Center

An anonymous bidding protocol without any reliable center for a small community is proposed. The anonymity of a bidding protocol means that the participation of everyone involved in the bidding except for the successful bidder is kept secret. Since it is hard for a small community to establish a reliable center owing to the difficulty and cost of doing so, an anonymous bidding protocol without any reliable center is appropriate to its needs. In such a bidding protocol, a bidder can withdraw his bid after the deadline for bidding by ceasing to participate in the bidding. If this can be done anonymously, the price of the successful bid would be illegally manipulated by conspiratorial bidders. In the bidding protocol proposed in this paper, such a bidder can be identified. This discourages conspiratorial bidders from manipulating the price of the successful bid through withdrawing, by applying some sanctions against their acts.