Section: New Results
Preservation of Privacy
Participant : Sébastien Gambs.
We describe herein only the research activities corresponding to papers co-authored by Sébastien Gambs and published since september 2009 (date of his arrival in the project team).
Privacy-preserving Identification System
We aim at studying privacy-preserving identification systems. In a joint work with Yves Deswarte (LAAS)  , we propose to replace the national identity card, currently used in many countries, by a personal device that allows its user to prove some binary statements about himself while minimizing personal information leakage. The privacy of the user is protected through the use of anonymous credentials which allows him to prove binary statements about himself to another entity without having to disclose his identity or any unnecessary information. The proposed scheme also prevents the possibility of tracing the user, even if he proves several times the same statement (unlinkability property). A tamper-proof smartcard is used to store the personal information of the user thus protecting his privacy and preventing the risks of forgery at the same time. The user identifies himself to the card via biometrics thus forbidding an unauthorized use in the situation where the card is stolen or lost. Two practical implementations of the privacy-preserving identity card are described and discussed. This research was mainly conducted when Sébastien Gambs was a CNRS postdoctoral researcher at LAAS-CNRS, Toulouse (from October 2008 to August 2009).
Privacy in Social Networking Sites
Social Networking Sites (SNS), such as Facebook and LinkedIn, have become the established place for keeping contact with old friends and meeting new acquaintances. As a result, a user leaves a big trail of personal information about him and his friends on the SNS, sometimes even without being aware of it. This information can lead to privacy drifts such as damaging his reputation and credibility, security risks (for instance identity theft) and profiling risks. In an ongoing collaboration  with Ai Thanh Ho and Esma Aïmeur (Université de Montréal), we first highlight some privacy issues raised by the growing development of SNS and identify clearly three privacy risks. While it may seem a priori that privacy and SNS are two antagonist concepts, we also identified some privacy criteria that SNS could fulfill in order to be more respectful of the privacy of their users. Finally, we introduce the concept of a Privacy-enhanced Social Networking Site (PSNS) and we describe Privacy Watch, our first implementation of a PSNS.
A geolocalised system generally belongs to an individual and as such knowing its location reveals the location of its owner, which is a direct threat against his privacy. To protect the privacy of users, a sanitization process, which adds uncertainty to the data and removes some sensible information, can be performed but at the cost of a decrease of utility due to the quality degradation of the data. In a joint work with Marc-Olivier Killijian (LAAS)  , we introduce GEPETO (for GEoPrivacy-Enhancing TOolkit), a flexible open source software which can be used to visualize, sanitize, perform inference attacks and measure the utility of a particular geolocalised dataset. The main objective of GEPETO is to enable a user to design, tune, experiment and evaluate various sanitization algorithms and inference attacks as well as visualizing the following results and evaluating the resulting trade-off between privacy and utility.