An Efficient,Privacy-preserving,and Verifiable Online Auction Mechanism For Ad Exchanges

Ad exchange,as a new online advertising real-time trading system,has become one of the most popular online advertising marketplaces for trading ad spaces over the Internet.Ad Exchange links buyers and sellers of online ad deals,that are advertisers and publishers,with online auctions using Real Time Bidding(RTB)technique,on behalf of the publishers to sell ad slots to advertisers,so as to help advertisers to win the opportunity to display ads and also to maximize the interests of the overall situation.However,due to the complexity and concealment of online auctions,advertisers and publishers can not participate in online auction decision-making process,and thus can not accurately verify if the online auction results are correct or not.In this case,the advertisers and publishers have no choice but to unconditionally believe the authority of Ad Exchange.In addition,advertisers often worry that online auctions will reveal their sensitive data,such as bid prices,so they may not be willing to participate in the auction process.In this paper,we jointly consider the auction verifiability and advertisers' privacy preservation,and propose ERA,which is an Efficient,pRivacy-preserving,and verifiAble online auction mechanism for ad exchanges.ERA exploits an Order Preserving Encryption Scheme(OPES)to guarantee privacy-preservation,and achieves verifiability by integrating a Certified Bulletin Board(CBB)and a protocol of Privacy-Preserving Integer Comparison(PPIC),which is based on the Paillier's Homomorphic Encryption Scheme(PHES).We prove that the ERA mechanism can satisfy privacy preservation and verifiability through theoretical analysis.We also extensively evaluate the performance of ERA in online auction scenarios.The evaluation results show that ERA satisfies the properties of verifiability and privacy-preservation with low overhead,and thus can be easily deployed in today's ad exchange platforms.