SBRAC: Blockchain-based sealed-bid auction with bidding price privacy and public verifiability

Electronic auction (e-auction) has become one of the most popular approaches to allocate resources or services in contemporary society because of removing physical limitations of traditional auctions. The rapid expansion of e-auction enhances work efficiency but incurs some new and distinctive challenges such as low-robustness, data privacy, and lack of trust. To address the above concerns, various auction designs have been proposed by researchers from the academic and industrial circles. However, most of them fail in simultaneously achieving decentralization (i.e. auctioneer-free), privacy-preserving (i.e. bids privacy), collusion-resistance, and secure-channel free. In this paper, we present an effective smart contract-based verifiable privacy-preserving sealed-bid reverse auction scheme, which not only has no need for trusted third parties, but also achieves robustness and privacy protection of losing bids even in the face of overwhelming collusion. In this scheme, the central auctioneer is replaced with some carefully designed smart contracts for decentralization, while zero-knowledge proof and anonymous veto networks are used to avoid the secret communication channel, support the public verifiability and detect the malicious behaviors of bidders. More practically, the complexity of the designed scheme is independent of the number of bidders. Finally, we implement a prototype of our design based on a locally simulated Ethereum test network. The extensive experimental results demonstrate the scheme is the high efficiency and practicality.