In a traditional electronic auction, the centralized auctioneer and decentralized bidders are in an asymmetric structure, where the auctioneer has more ability to decide the auction result. This asymmetric auction structure is not fair to the participants and not suitable for data auctions in the Internet of Things (IoT). The blockchain-based auction system, with participant equality and fairness, is typically symmetrical and particularly suitable for IoT data sharing. However, when applied to IoT data sharing in reality, it faces privacy and efficiency problems. In this context, how to guarantee privacy and break the inherent performance bottleneck of blockchain is still a major challenge. In this paper, a consensus-based distributed auction scheme is proposed for data sharing, which enforces privacy preservation and collusion resistance. A reverse auction-based decentralized data trading model is introduced to solve the trust problem without a centralized auctioneer, where bidders reach consensus on the auction result. Specifically, we devise a differentially private auction mechanism to incentivize data owners to participate in data sharing. An effective hybrid consensus algorithm is constructed among bidders to reach consensus on the auction result with improved security and efficiency. Theoretical analysis shows that the proposed scheme ensures the properties of privacy preservation, incentive compatibility and collusion resistance. Experimental results reveal that the proposed mechanism guarantees the data sharing efficiency and has certain scalability.

Although widely applied in varied scenarios, unmanned aerial vehicles (UAVs) suffer severe flight time and flight range limitations due to constrained onboard battery capacity, causing frequent battery recharging when performing persistent missions. The wireless power transfer technology is a promising solution for UAV charging by utilizing unmanned ground vehicles (UGVs) equipped with wireless charging facilities, where charging time slots are auctioned and assigned to UAVs. However, UGVs themselves also have limited energy capacity, resulting in the need to revoke a UAV charging transaction after auction to satisfy their own demand if necessary. In addition, as UAVs and UGVs are mutually distrustful, inherent security and privacy concerns must be resolved during the revocation. In this paper, we resort to blockchain technology for secure and efficient revocable charging in vehicle-assisted wireless UAV networks. We present PAS, an efficient privacy-preserving attestation scheme for revocable UAV charging based on hybrid state channels, where UAVs and UGVs perform off-chain operations as blockchain users for privacy and efficiency, while security and fairness are guaranteed by the on-chain mechanism. PAS consists of a multi-party state channel and multiple two-party state channels responsible for charging scheduling and transaction revocation, respectively. PAS ensures fair and private revocation negotiation and compensation in a trust-free manner by developing a set of carefully designed modular protocols. We provide PAS’ constituent primitives in detail, prove its security properties following the universally composable (UC) framework, and present experimental results to demonstrate its feasibility and scalability.