P2: A Location Privacy-Preserving Auction Mechanism for Mobile Crowd Sensing

It is of significant importance to provide incentives to smartphone users in mobile crowd sensing systems. And a number of auction-based incentive mechanisms have been proposed. However, an auction-based incentive mechanism may unexpectedly release the location privacy of smartphone users, which may seriously reduce users' willingness of participating in mobile crowd sensing. In an auction-based mechanism, even if the location of the user is not enclosed in its bid submitted to the platform, the location information may still be inferred by an adversary by using the prices of the tasks required by the user. We show such an attack on a typical auction-based incentive mechanism and reveal that the attack can recover the location information of a smartphone user by merely knowing the bid from the user. To defend against such an attack, we propose P², a location privacy-preserving auction mechanism for mobile crowd sensing systems. This mechanism encrypts prices in a bid so that the adversary cannot access and hence the location privacy of the user can be protected. In the meanwhile, however, the auction can proceed properly, i.e., the platform can select the user offering the lowest price for each sensing task. We demonstrate the effectiveness of our the proposed mechanism with simulation experiments.