PhD Position “Privacy Preserving Query Processing in Decentralized Online Social Networks”, April 28, 2015

PhD Position: Privacy Preserving Query Processing in Decentralized Online Social Networks


We propose a PhD position (CIFRE) which will be done in the context of collaboration between INRIA Zenith team ( and MatchUpBox startup ( that is developing a P2P social network application whose objective is to enable users to share their content while preserving the sensible data from unauthorized access.

Recently, there has been a growing research interest in extending privacy preserving techniques for social networks. One of the main challenges is to develop practical solutions that protect the users’ sensitive data while offering a good degree of utility for the queries executed over the published data.

The objective of this PhD thesis is to provide a query processing service that allows efficient evaluation of OLAP (Online analytical processing) queries without disclosing any information about individual data. An example of such queries is the following: given a topic, what is the percentage of the users interested in the topic? For realizing such a service, we need a distributed architecture allowing us to control the queries asked on each user data, and to block the answers if the privacy restrictions are not respected. The queries should be executed in a fully decentralized way, and the communications between the nodes should be secure. We also need to take into account the particular characteristics of the P2P architectures, especially the dynamic behavior of peers that can leave the system any time.

Missions and activities

The tasks to be realized are the following:

  • Investigating the state-of-the-art approaches for privacy preservation in social networks.
  • Proposing a distributed architecture for the service of privacy preserving query processing.
  • Proposing efficient techniques for some important OLAP queries which will be used in the application.
  • Implementing a prototype of the proposed service.
  • Evaluating the prototype in a distributed platform, such as Grid5000.

Skills and profiles

We will study all applications carefully. But, an ideal applicant may have the following skills:

  • Experience in privacy preserving methods (or cryptography).
  • Strong knowledge of C++ or Java.


The Zenith project-team of INRIA (, headed by Patrick Valduriez, aims to propose new solutions related to distributed data management. The research topics of Zenith include: parallel processing of massive data, recommendation in social networks, privacy preservation data analysis, probabilistic data management, etc.

MatchUpBox ( is an innovative startup specialized in data security and privacy. It is developing a social network that helps the users regain the control of their data and to interact safely on the Internet. The uses are anonymous any time they are connected. All the content the users put to the social network provided by MatchUpBox is protected and only accessible to the owner and those whom he/she authorizes.

Both Zenith and MatchUpBox are located in Montpellier that is a very active town located in south of France.

How to apply

To apply for this PhD position, please send your CV and a motivation letter to the following email addresses:

  • Reza Akbarinia (
  • Esther Pacitti (
  • Jorick Lartigau (

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