## Section: Software

### A model checker for the probabilistic asynchronous $\pi $-calculus

Participants : Miguel Andrés [correspondant] , Catuscia Palamidessi.

In collaborations with Dave Parker and Marta Kwiatkowska, we are developing a model checker for the probabilistic asynchronous $\pi $-calculus. Case studies with Fair Exchange and MUTE, an anonymous peer-to-peer file sharing system, are in progress.

Technically we use MMC as a compiler to encode the probabilistic $\pi $-calculus into certain PRISM representation, which will then be verified against PCTL using PRISM. The transitional semantics defined in MMC can be reused to derive the symbolic transition graphs of a probabilistic process. The code for derivation will work as an add-on to MMC under XSB and invoke a graph traversal to enumerate all reachable nodes and transitions of the probabilistic process.

In the meanwhile we are also attempting a direct and more flexible approach to the development of a model checker for the probabilistic $\pi $-calculus, using OCaml. This should allow to extend the language more easily, to include cryptographic primitives and other features useful for the specification of security protocols. As the result of our preliminary steps in this direction we have developed a rudimentary model checker, available at the following URL: http://vamp.gforge.inria.fr/ .