Formal Analysis of Security Protocols for Wireless Sensor Networks

Design of security protocols is notoriously error-prone. For this reason, it is required to use formal methods to analyze their security properties. In the paper we present a formal analysis of the Canvas protocol. The Canvas protocol was developed by Harald Vogt and should provide data integrity in Wireless Sensor Networks. However, Dieter Gollmann published an attack on the protocol. We consider the fallacy of the Canvas scheme in different models of the attacker and present a solution for correcting the scheme. We propose a formal model of the fixed Canvas protocol in the applied pi-calculus. This model includes a model of the network topology, communication channels, captured nodes, and capabilities of the attacker. Moreover, we formulate and analyze the data integrity property of the scheme in the semantic model of the applied pi-calculus. We prove that the fixed Canvas scheme, in the presence of an active adversary, provides data integrity of messages assuming that captured nodes are not direct neighbors in the communication graph of a sensor network. Finally, we discuss the applicability of the proposed formal model for analysis of other WSN security protocols.