A Predictive Differentially-Private Mechanism for Mobility Traces

Konstantinos Chatzikokolakis 1, 2 Catuscia Palamidessi 1, 3 Marco Stronati 1, 2
1 COMETE - Concurrency, Mobility and Transactions
LIX - Laboratoire d'informatique de l'École polytechnique [Palaiseau], Inria Saclay - Ile de France, Polytechnique - X, CNRS - Centre National de la Recherche Scientifique : UMR7161
Abstract : With the increasing popularity of GPS-enabled hand-held devices, location-based applications and services have access to accurate and real-time location information, raising serious privacy concerns for their millions of users. Trying to address these issues, the notion of geo-indistinguishability was recently introduced, adapting the well-known concept of Differential Privacy to the area of location-based systems. A Laplace-based obfuscation mechanism satisfying this privacy notion works well in the case of a sporadic use; Under repeated use, however, independently applying noise leads to a quick loss of privacy due to the correlation between the location in the trace. In this paper we show that correlations in the trace can be in fact exploited in terms of a prediction function that tries to guess the new location based on the previously reported locations. The proposed mechanism tests the quality of the predicted location using a private test; in case of success the prediction is reported otherwise the location is sanitized with new noise. If there is considerable correlation in the input trace, the extra cost of the test is small compared to the savings in budget, leading to a more efficient mechanism. We evaluate the mechanism in the case of a user accessing a location-based service while moving around in a city. Using a simple prediction function and two budget spending stategies, optimizing either the utility or the budget consumption rate, we show that the predictive mechanim can offer substantial improvements over the independently applied noise.
Type de document :
Communication dans un congrès
Emiliano De Cristofaro and Steven J. Murdoch. PETS 2014 - 14th Privacy Enhancing Technologies Symposium, Jul 2014, Amsterdam, Netherlands. Springer, 8555, pp.21-41, 2014, Lecture Notes in Computer Science. 〈10.1007/978-3-319-08506-7_2〉
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https://hal.inria.fr/hal-01011260
Contributeur : Catuscia Palamidessi <>
Soumis le : lundi 23 juin 2014 - 14:29:26
Dernière modification le : jeudi 9 février 2017 - 15:10:38

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Konstantinos Chatzikokolakis, Catuscia Palamidessi, Marco Stronati. A Predictive Differentially-Private Mechanism for Mobility Traces. Emiliano De Cristofaro and Steven J. Murdoch. PETS 2014 - 14th Privacy Enhancing Technologies Symposium, Jul 2014, Amsterdam, Netherlands. Springer, 8555, pp.21-41, 2014, Lecture Notes in Computer Science. 〈10.1007/978-3-319-08506-7_2〉. 〈hal-01011260〉

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