An Efficient, Privacy-Preserving, and Verifiable Online Auction Mechanism for Ad Exchanges

Ad exchanges are kind of the most popular online advertising marketplaces for trading ad spaces over the Internet. Ad exchanges run auctions to sell the ad spaces on publishers´ web-pages to advertisers, who want to display ads on the ad spaces. However, the parties in the auction cannot check whether the auction is carried out correctly or not. Furthermore, the advertisers are usually not willing to reveal their sensitive information when participating in the auction. 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 extensively evaluate the performance of ERA, and our evaluation results show that ERA satisfies the properties of verifiability and privacy-preservation with low overhead, so ERA can be easily deployed in today´s ad exchanges.