Formal Verification of Secrecy in Group Key Protocols Using Event-B

Abstract

Group key security protocols play an important role in today's communication systems. Their verification, however, remains a great challenge because of the dynamic characteristics of group key construction and distribution protocols. Security properties that are well defined in normal two-party protocols have different meanings and different interpretations in group key distribution protocols, specifically, secrecy properties, such as group secrecy, forward secrecy, backward secrecy, and key independence. In this paper, we present a method to verify forward secrecy properties for group-oriented protocols. The method is based on a correct semantical link between group key protocols and event-B models and also uses the refinement process in the B method to model and verify group and forward secrecy. We use an event-B first-order theorem proving system to provide invariant checking for these secrecy properties. We illustrate our approach on the Tree based Group Diffie-Hellman protocol as case study.

A methodology for assuring the safety and security of critical infrastructure based on STPA and Event-B

“…Formal methods have been used in order to develop systems from parts of Amazon Web Services (Newcombe et al, 2015) to assurance of the software powering safety-critical aspects of a line of the Paris Metro system (Behm et al, 1999). We pay particular attention to a development of the B-method, known as Event-B (Abrial, 2010), which has been leveraged for both security analysis (Gawanmeh et al, 2012) as well as safety analysis (Rezazadeh et al, 2007) and has therefore proven itself useful in both domains. Furthermore, Event-B has been paired with an STPA methodology in the past which has demonstrated synergies between STPA's constraint-based approach and Event-B's modelling techniques (Colley and Butler, 2013).…”