Design and Analysis of a Generalized Canvas Protocol

The Canvas protocol was developed by Harald Vogt [10] and should provide data integrity in Wireless Sensor Networks. However, Dieter Gollmann published [5] an attack on the protocol. This example supports a widespread belief that design of security protocols is notoriously error-prone. Therefore, it is required to use formal methods to analyze their security properties. In the paper we present design and analysis of a generalized Canvas protocol. We consider the fallacy of the Canvas scheme in different models of the attacker and present a solution for correcting the scheme. We discuss a motivation for generalization of the Canvas protocol and introduce a k-generalized version of the scheme for some parameter k ≥ 2. We build a formal model of the k-generalized 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. In the semantic model of the applied picalculus we specify the data integrity property of the scheme. We prove that the proposed k-generalized Canvas scheme, in the presence of an active adversary, provides data integrity of messages assuming that at least one honest node exists on each path of the length k− 1 in the communication graph of a sensor network. Finally, we discuss the usability of the proposed formal model for other WSN security protocols.