A Specification-based State Replication Approach for Digital Twins

Digital twins play a key role in realizing the vision of a smart factory. While this concept is often associated with maintenance, optimization, and simulation, digital twins can also be leveraged to enhance the security and safety of cyber-physical systems (CPSs). In particular, digital twins can run in parallel to a CPS, allowing to perform a security and safety analysis during operation without the risk of disrupting live systems. However, replicating states of physical devices within a CPS in functionally equivalent virtual replicas, so that they precisely mirror the internal behavior of their counterparts, is an open research topic. In this paper, we propose a novel state replication approach that first identifies stimuli based on the system's specification and then replicates them in a virtual environment. We believe that replicating states of CPSs is a prerequisite for a multitude of security and safety enhancing features that can be implemented on the basis of digital twins. To demonstrate the feasibility of the specification-based state replication approach, we provide a prototypical implementation and evaluate it in an experimental CPS test bed. The results of this paper show that attacks against CPSs can be successfully detected by leveraging the proposed state replication approach.