Events in security protocols

Abstract

The events of a security protocol and their causal dependency can play an important role in the analysis of security properties. This insight underlies both strand spaces and the inductive method. But neither of these approaches builds up the events of a protocol in a compositional way, so that there is an informal spring from the protocol to its model. By broadening the models to certain kinds of Petri nets, a restricted form of contextual nets, a compositional eventbased semantics is given to an economical, but expressive, language for describing security protocols; so the events and dependency of a wide range of protocols are determined once and for all. The net semantics is formally related to a transition semantics, strand spaces and inductive rules, as well as trace languages and event structures, so unifying a range of approaches, as well as providing conditions under which particular, more limited, models are adequate for the analysis of protocols. The net semantics allows the derivation of general properties and proof principles which are demonstrated in establishing an authentication property, following a diagrammatic style of proof.

Wireless authentication in χ-Spaces

“…We use the net-semantics of SPL (see [CW01]) to formally state and prove security properties. As shown in [CW01], to each protocol run in the transition semantics of SPL corresponds a run in its net semantics.…”

“…The SPL net-semantics supports formal analysis of protocols and their security properties. The operational semantics and the Petri-net semantics of SPL are closely related [CW01]. As a consequence, properties of the SPL Petri-net model of a protocol hold for its χ-Spaces implementation.…”

“…χ-Spaces implements the formal operational semantics of SPL [CW01], a concise, yet powerful scripting language designed for the specification of security protocol. The SPL net-semantics supports formal analysis of protocols and their security properties.…”

A framework for the development of protocols

“…The Petri-net semantics of the language supports formal proofs about the security of protocols [1,2,5,6]. Due to its close relation to the implemented transition semantics (see [2]), proved properties are properties of protocol implementations. The simple, yet formal transition semantics of χ-Spaces describes the behavior of a system communicating via a tuple space.…”

“…The χ-Spaces language is an implementation of SPL [1,2]; protocols programmed with χ-Spaces are concise (most fit in less than one page) and enjoy rigorous semantics -a more traditional transitions-system semantics and a Petri-net semantics, both closely related [2]. We implemented the transition semantics, and use the net semantics to verify security properties of protocols.…”