1. Introduction
Security protocols are communication protocols in which cryptography is used to give participants thecapability to transmit encoded information that can be only decoded by the designated receivers. These protocols have been intensively analyzed throughout the last few decades, resulting in a variety of dedicated formal methods and tools [[1], [5], [7], [8], [13], [14], [16]]. The majority of these methodsconsider a Dolev-Yao-like penetrator model [6] to capture the actions available to a penetrator which has complete control over the network. By analyzing each individual protocol in the presence of this penetrator model, the literature has reported numerous types of attacks [3], [8]. However, in practice, there can be multiple protocols running over the same network, thus the penetrator is given new opportunities to construct attacks by combining messages from several protocols, also known as multi-protocol attacks [10].