Formally Reasoning About Security Issues in P2P Protocols: A Case Study

Peer-to-Peer (P2P) systems can be seen as highly dynamic distributed systems designed for very specific purposes, such as resources sharing in collaborative settings. Because of their ubiquity, it is fundamental to provide techniques for formally proving properties of the communication protocols underlying those systems. In this paper we present a formal specification of MUTE, a protocol for P2P systems, modelled in the SPL process calculus. Furthermore, we use the SPL reasoning techniques to show how the protocol enjoys a secrecy property against outsider attacks. By formally modeling and analyzing a real-world, yet informally specified protocol, we bear witness to the applicability of SPL as a formalism to specify security protocols as well as the flexibility of its reasoning techniques. This paper represents our first approach towards the use of process calculi, in particular SPL, for the specification and reasoning of P2P protocols.