Verification of the MQTT IoT Protocol Using Property-Specific CTL Sweep-Line Algorithms

Abstract

MQTT is a publish-subscribe communication protocol being increasingly used for implementing internet-of-things (IoT) applications. In earlier work we have developed a formal and executable model of the MQTT protocol using Coloured Petri Nets (CPNs) and performed an initial verification of behavioural properties. The contribution of this paper is to investigate the use of the sweep-line method for verification of the MQTT CPN model in order to alleviate the effect of the state explosion problem. We formulate the behavioural properties using Computation Tree Logic (CTL) and show how to formulate a progress measure for the sweep-line method based on the main phases of the MQTT protocol. To perform the verification of properties, we provide some property-specific CTL model checking algorithms compatible with the sweep-line method.