Encrypted control for networked systems -- An illustrative introduction and current challenges

Cloud computing and distributed computing are becoming ubiquitous in many modern control systems such as smart grids, building automation, robot swarms or intelligent transportation systems. Compared to "isolated" control systems, the advantages of cloud-based and distributed control systems are, in particular, resource pooling and outsourcing, rapid scalability, and high performance. However, these capabilities do not come without risks. In fact, the involved communication and processing of sensitive data via public networks and on third-party platforms promote, among other cyberthreats, eavesdropping and manipulation of data. Encrypted control addresses this security gap and provides confidentiality of the processed data in the entire control loop. This paper presents a tutorial-style introduction to this young but emerging field in the framework of secure control for networked dynamical systems.Comment: The paper is a preprint of an accepted paper in the IEEE Control Systems Magazin

Encrypted cooperative control based on structured feedback

Cooperative control for multi-agent systems usually requires some communication between the various subsystems. In the resulting networked control system, sensitive data is transmitted and shared between the agents. We propose a novel encrypted control scheme that ensures privacy of the individual agents' data not only during transmission but also during controller evaluations at neighboring agents. Our control scheme efficiently combines the design of structured feedback laws for multi-agent systems with encrypted controllers for conventional linear systems. The underlying key technology is partial homomorphic encryption, which allows simple computations to be carried out on encrypted data.</p