Soutenance de thèse : Besma KHALFOUN

Privacy preserving location based services: from centralised to federated approaches

Doctorante : Besma KHALFOUN

Laboratoire INSA : LIRIS

Ecole doctorale : ED512 Informatique et mathématiques de Lyon

Nowadays, a wide variety of online services are being used by billions of users on a daily basis among other location-based services. Key to the success of these services is the personalization of users’ results, i.e., returning to each user the results that are closer to her interests. For instance, in the context of location-based services, user profiles contain user mobility data from which it is easy to infer information such as a user’s home and workplace or even her sexual, religious, or political preferences if she regularly visits gay bars, worship places or the headquarter of a political party.
However, user profiles, which online service providers widely exploit due to their inherent business model based on online advertising, might severely threaten user privacy if they end up in the hands of untrusted entities. Recent events have shown that the latter risk of data privacy leakage is becoming a reality due to the massive use of cloud services by online service providers and by end-users. Indeed, a 2014 study from Gartner found that 94% of organizations either already are or plan to store their consumer data in the cloud. Another study by the same organization envisions that the "Cloud Shift" by 2020 will affect more than $1 Trillion in IT spending. On the same line, cloud providers are experiencing exponential growth in their storage capabilities. Due to their success and the unprecedented value that can be extracted from the data they store (e.g., financial information, health information, trade secrets, intellectual property), cloud providers are becoming the target of devastating attacks. Examples of such attacks that took place in 2016 include hospital ransomware, millions of Dropbox account details leaked, and other millions of Snapchat accounts compromised to cite a few.
In this context, it becomes urgent to devise mechanisms that allow users to securely access online services without fearing that their data will be leaked out from the cloud platforms where it is being stored and processed.