Fully Private Auctions in a Constant Number of Rounds

Abstract. We present a new cryptographic auction protocol that prevents extraction of bid information despite any collusion of participants. This requirement is stronger than common assumptions in existing protocols that prohibit the collusion of certain third-parties (e.g. distinct auctioneers). Full privacy is obtained by using homomorphic ElGamal encryption and a private key that is distributed among the set of bidders. Bidders jointly compute the auction outcome on their own without uncovering any additional information in a constant number of rounds (three in the random oracle model). No auctioneers or other trusted third parties are needed to resolve the auction. Yet, robustness is assured due to public verifiability of the entire protocol. The scheme can be applied to any uniform-price (or so-called (M + 1)st-price) auction. An additional, optional, feature of the protocol is that the selling price is only revealed to the seller and the winning bidders themselves. We furthermor...

• Type: Conference
• Year: 2003
• Where: FC
• Authors: Felix Brandt
• Keywords: Cryptographic Auction Protocol, FC 2003, Homomorphic Elgamal Encryption, Random Oracle Model