Using homomorphic encryption to secure the combinatorial spectrum auction without the trustworthy auctioneer

Spectrum auction is an enabling technology for improving the spectrum efficiency of unused licensed bands (white spaces) in wireless networks. However, the back-room dealing (i.e., the frauds of the untrustworthy auctioneer and the bid-rigging between the greedy bidders and the insincere auctioneer) poses serious security challenges, leading to failures of all existing secure auction designs in allocating spectrum bands. In this paper, we propose a secure combinatorial spectrum auction (SCSA) by utilizing homomorphic encryption to prevent the backroom dealing. The idea in SCSA is to incorporate cryptographic techniques into the spectrum auction to address the frauds and bid-rigging. It computes and reveals the results of spectrum auction while the actual bidding values of bidders are kept confidential. SCSA also provides a corresponding procedure in implementing the combinatorial spectrum auction under the interference constraints. We show that compared with existing secure spectrum auction designs against the untrustworthy auctioneer, SCSA is much more efficient in both communication and computational complexity; and compared with other spectrum auction designs with security consideration, SCSA can effectively thwart the back-room dealings due to the untrustworthy auctioneer without too much performance degradation.