Location Privacy Protection in Social Networks

University of Technology Sydney. Faculty of Engineering and Information Technology.Social networks have become more ubiquitous due to new advances in smartphone technology. This has provided an opportunity for social network service providers to utilise location information of users in their services. For example, Facebook Places, Foursquare and Yelp are popular social networks that mostly rely on utilising users' location data in their services. They offer a variety of useful services, from location recommendations to nearby friend alerts. However, protecting location privacy of users is still an open challenge for social network service providers. It has been shown that hiding real identity and choosing a pseudonym does not guarantee to protect a user's privacy since privacy may be invaded by analysing position data only. This is really a big issue since other private information of users can be revealed by analysing their location data (e.g., home address, health condition, interests, etc.). In this study, we investigate the location privacy issue of social networks and propose several solutions. We classify the proposed solutions into three categories based on the selected approaches, i.e. (i) differential privacy-based, (ii) cryptography-based, and (iii) anonymity-based solutions. We first study the approach in which differential privacy is utilised to preserve privacy of users. In this regard, we develop Distance-Based Location Privacy Protection mechanism (DBLP2), a customisable location privacy protection approach that is uniquely designed for social network users. It utilises the concept of social distance to generalise users' location data before it is published in a social network. The level of generalisation is decided based on the social distance between users. Secondly, we study cryptography-based methods for location privacy protection in Location-Based Services (LBS) and social networks. In this domain, we propose three cryptography-based and privacy-aware location verification schemes to preserve location privacy of users: (i) Privacy-Aware and Secure Proof Of pRoximiTy (PASPORT), (ii) Secure, Privacy-Aware and collusion Resistant poSition vErification (SPARSE), and (iii) a blockchain-based location verification scheme. These schemes prevent location spoofing attacks conducted by dishonest users while protect location privacy of users. To the best of our knowledge, majority of the existing location verification schemes do not preserve location privacy of users. Thirdly, we investigate anonymity as another approach to preserve users' privacy in social networks. In this regard, we first study the relevant protocols and discuss their features and drawbacks. Then, we introduce Harmonized and Stable DC-net (HSDC-net), a self-organizing protocol for anonymous communications in social networks. As far as we know, social networks do not offer any secure anonymous communication service. In social networks, privacy of users is preserved using pseudonymity, i.e., users select a pseudonym for their communications instead of their real identity. However, it has been shown that pseudonymity does not always result in anonymity (perfect privacy) if users' activities in social media are linkable. This makes users' privacy vulnerable to deanonymization attacks. Thus, by employing a secure anonymous communication service, social network service providers will be able to effectively preserve users' privacy. We perform extensive experiments and provide comprehensive security and privacy analysis to evaluate performance of the proposed schemes and mechanisms. Regarding the DBLP2 mechanism, our extensive analysis shows that it offers the optimum data utility regarding the trade-off between privacy protection and data utility. In addition, our experimental results indicate that DBLP2 is capable of offering variable location privacy protection and resilience to post processing. For the SPARSE scheme, our analysis and experiments show that SPARSE provides privacy protection as well as security properties for users including integrity, unforgeability and non-transferability of the location proofs. Moreover, it achieves a highly reliable performance against collusions. To validate performance of the PASPORT scheme, we implement a prototype of the proposed scheme on the Android platform. Extensive experiments indicate that the proposed method can efficiently protect location-based applications against fake submissions. For the proposed blockchain-based scheme, our prototype implementation on the Android platform shows that the proposed scheme outperforms other currently deployed location proof schemes. Finally, our prototype implementation of the HSDC-net protocol shows that it achieves low latencies that makes it a practical protocol. In summary, this research study focuses on developing new mechanisms for preserving location privacy of social network users. This is done through different approaches. Moreover, extensive effort is made to make the current location-related schemes and protocols privacy-aware. In this regard, several solutions in the form of scheme, mechanism, and protocol are introduced and their performance is evaluated. The results of this research work have also been presented in seven papers published in peer-reviewed journals and conferences

Localization to Enhance Security and Services in Wi-Fi Networks under Privacy Constraints

Developments of seamless mobile services are faced with two broad challenges, systems security and user privacy - access to wireless systems is highly insecure due to the lack of physical boundaries and, secondly, location based services (LBS) could be used to extract highly sensitive user information. In this paper, we describe our work on developing systems which exploit location information to enhance security and services under privacy constraints. We describe two complimentary methods which we have developed to track node location information within production University Campus Networks comprising of large numbers of users. The location data is used to enhance security and services. Specifically, we describe a method for creating geographic firewalls which allows us to restrict and enhance services to individual users within a specific containment area regardless of physical association. We also report our work on LBS development to provide visualization of spatio-temporal node distribution under privacy considerations

Incentive Mechanisms for Participatory Sensing: Survey and Research Challenges

Participatory sensing is a powerful paradigm which takes advantage of smartphones to collect and analyze data beyond the scale of what was previously possible. Given that participatory sensing systems rely completely on the users' willingness to submit up-to-date and accurate information, it is paramount to effectively incentivize users' active and reliable participation. In this paper, we survey existing literature on incentive mechanisms for participatory sensing systems. In particular, we present a taxonomy of existing incentive mechanisms for participatory sensing systems, which are subsequently discussed in depth by comparing and contrasting different approaches. Finally, we discuss an agenda of open research challenges in incentivizing users in participatory sensing.Comment: Updated version, 4/25/201