Toward Privacy Preserving and collusion Resistance

Abstract

Today’s location-sensitive service relies on user’s mobile device to determine the current location. This allows malicious users to access a restricted resource or provide bogus alibis by cheating on their locations. To address this issue, we propose A Privacy-Preserving LocAtion proof Updating System (APPLAUS) in which colocated Bluetooth enabled mobile devices mutually generate location proofs and send updates to a location proof server. Periodically changed pseudonyms are used by the mobile devices to protect source location privacy from each other, and from the untrusted location proof server. We develop user-centric location privacy model in which individual users evaluate their location privacy levels and decide whether and when to accept the location proof requests. In order to defend against colluding attacks, we also present between ness ranking-based and correlation clustering-based approaches for outlier detection. APPLAUS can be implemented with existing network infrastructure, and can be easily deployed in Bluetooth enabled mobile devices with little computation or power cost. Extensive experimental results show that APPLAUS can effectively provide location proofs, significantly preserve the source location privacy, and effectively detect colluding attacks.

Existing System

The common theme across these location sensitive applications is that they offer a reward or benefit to users located in a certain geographical location at a certain time. Thus, users have the incentive to cheat on their locations. Location-sensitive applications require users to prove that they really are (or were) at the claimed locations. Although most mobile users have devices capable of discovering their locations, some users may cheat on their locations and there is a lack of secure mechanism to provide their current or past locations to applications and services. One possible solution is to build a trusted computing module on each mobile device to make sure trusted GPS data is generated and transmitted. For example, Lenders et al. proposed such a solution which can be used to generate unforgeable geotagsfor mobile content such as photos and video; however, it relies on the expensive trusted computing module on mobile devices to generate proofs. Although cellular service providers have tracking services that can help verify the locations of mobile users in real time, the accuracy is not good enough and the location history cannot be verified.

Proposed System

In this paper, we propose APPLAUS which does not rely on the wide deployment of network infrastructure or the expensive trusted computing module. In APPLAUS, Bluetooth enabled mobile devices in range mutually generate location proofs, which are uploaded to a untrusted location proof server that can verify the trust level of each location proof. An authorized verifier can query and retrieve location proofs from the server. Moreover, our location proof system guarantees user location privacy from every party. More specifically, we use statistically updated pseudonyms at each mobile device to protect location privacy from each other, and from the untrusted location proof server. We develop a user-centric location privacy model in which individual users evaluate their location privacy levels in real time and decide whether and when to accept a location proof request. In order to defend against colluding attacks, we also present between ness ranking-based and correlation clustering-based approaches for outlier detection.

Architecture