Section: Application Domains

Security

Participants : Miguel Andrés, Romain Beauxis, Christelle Braun, Jérémy Dubreil, Mario Sergio Ferreira Alvim Junior, Catuscia Palamidessi, Geoffrey Smith.

The aim of our research is the specification and verification of protocols used in mobile distributed systems, in particular security protocols. We are especially interested in protocols for privacy , because they exhibit features that require the kind of concepts and approach in which we feel most competent. It is likely, however, that the instruments and tools developed having privacy in mind can later be useful and adaptable also to other domains of security, like Secure Information flow . Privacy is a generic term which denotes the issue of preventing certain information to become known to an agent, except in case that agent is explicitly allowed to be informed. It may refer to the protection of private data (credit card number, personal info etc.), of the agent's identity (anonymity ), of the link between information and user (unlinkability ), of its activities (unobservability ), and of its mobility (untraceability) .

The common denominator of this class of problems is that an adversary can try to infer the private information (secrets ) from the information that he can access (observables ). The purpose of privacy protocols is then to obfuscate the link between secrets and observables as much as possible, and they often use randomization to achieve this purpose, i.e. to introduce noise . The protocol can therefore be seen as a noisy channel , in the Information-Theoretic sense, between the secrets and the observables.

We intend to explore the rich set of concepts and techniques in the fields of Information Theory and Hypothesis Testing to establish the foundations of privacy, and to develop heuristics and methods to improve protocols for privacy. Our approach will be based on the specification of protocols in the probabilistic asynchronous -calculus, and the application of model-checking to compute the matrices associated to the corresponding channels.