Marc-Olivier Killijian

Show me how you move and I will tell you who you are

Due to the emergence of geolocated applications, more and more mobility traces are generated on a daily basis and collected in the form of geolocated datasets. If an unauthorized entity can access this data, it can used it to infer personal information about the individuals whose movements are contained within these datasets, such as learning their home and place of work or even their social network, thus causing a privacy breach. In order to protect the privacy of individuals, a sanitization process, which adds uncertainty to the data and removes some sensible information, has to be performed. The global objective of GEPETO (for GEoPrivacy Enhancing TOolkit) is to provide researchers concerned with geo-privacy with means to evaluate various sanitization techniques and inference attacks on geolocated data. In this paper, we report on our preliminary experiments with GEPETO for comparing different clustering algorithms and heuristics that can be used as inference attacks, and evaluate their efficiency for the identification of point of interests, as well as their resilience to sanitization mechanisms such as sampling and perturbation.

Dependability Evaluation of Cooperative Backup Strategies for Mobile Devices

Mobile devices (e.g., laptops, PDAs, cell phones) are increasingly relied on but are used in contexts that put them at risk of physical damage, loss or theft. This paper discusses the dependability evaluation of a cooperative backup service for mobile devices. Participating devices leverage encounters with other devices to temporarily replicate critical data. Permanent backups are created when the participating devices are able to access the fixed infrastructure. Several data replication and scattering strategies are presented, including the use of erasure codes. A methodology to model and evaluate them using Petri nets and Markov chains is described. We demonstrate that our cooperative backup service decreases the probability of data loss by a factor up to the ad hoc to Internet connectivity ratio.

NFLlib: NTT-Based Fast Lattice Library

Recent years have witnessed an increased interest in lattice cryptography. Besides its strong security guarantees, its simplicity and versatility make this powerful theoretical tool a promising competitive alternative to classical cryptographic schemes. n nIn this paper, we introduce NFLlib, an efficient and open-source C++ library dedicated to ideal lattice cryptography in the widely-spread polynomial ring

Robustness of automotive applications using reflective computing: lessons learnt

mathbb Z_{p}[x]/x^n+1

Locanyms: towards privacy-preserving location-based services

for n a power of 2. The library combines algorithmic optimizations Chinese Remainder Theorem, optimized Number Theoretic Transform together with programming optimization techniques SSE and AVX2 specializations, C++ expression templates, etc., and will be fully available under an open source license. n nThe library compares very favorably to other libraries used in ideal lattice cryptography implementations namely the generic number theory libraries NTL and flint implementing polynomial arithmetic, and the optimized library for lattice homomorphic encryption HElib: restricting the library to the aforementioned polynomial ring allows to gain several orders of magnitude in efficiency.

Souk: Spatial Observation of Human Kinetics ☆

We present the AMORES project, which aims to provide an architecture for the provision of privacy preserving and resilient collaborative services in mobiquitous (i.e., mobile and ubiquitous) systems. The project is built around three use-cases from the area of public transportation: (1) dynamic carpooling, (2) real-time computation of multimodal transportation itineraries and (3) mobile social networking. Four main research tasks are presented in this paper. The first task deals with use-cases, prototypes and privacy assessment. The second task addresses geo-communication primitives: verified positioning, locanyms and geo-services. The third task deals with privacy-preserving communication means such as anonymous routing and geo-cryptography. Finally, the last task is devoted to collaborative behaviors.

Meeting points in ridesharing: A privacy-preserving approach

In this paper, we present our experience and lessons learnt in applying a multi-level reflective approach to the design and implementation of an industrial embedded dependable system. We reflect in particular on the process by which ideal academic results and assumptions may be mapped to a concrete industrial context. More precisely, our reflection is based on our experience in building an adaptive defense software for a multilayer embedded platform in the automotive industry. This defense software provides a safety bag and is based on computational reflection, an advanced architectural mechanism to separate cross-cutting concerns. Our implementation uses the AUTOSAR middleware, the automotive standard for modular embedded software, and relies on software sensors to observe the behavior of the system, executable assertions to check on-line properties, and software actuators to perform recovery actions. This leads to defense software that is uncoupled from the real functional system and can be adjusted and specialized according to the needs of the system integrator.

Revised version of DSoS conceptual model

Mobile devices (e.g., laptops, PDAs, cell phones) are increasingly relied on but are used in contexts that put them at risk of physical damage, loss or theft. This paper discusses security considerations that arise in the design of a cooperative backup service for mobile devices. Participating devices leverage encounters with other devices to temporarily replicate critical data. Anyone is free to participate in the cooperative service, without requiring any prior trust relationship with other participants. In this paper, we identify security threats relevant in this context as well as possible solutions and discuss how they map to low-level security requirements related to identity and trust establishment. We propose self-organized, policy-neutral mechanisms that allow the secure designation and identification of participating devices. We show that they can serve as a building block for a wide range of cooperation policies that address most of the security threats we are concerned with. We conclude on future directions.