Cybersecurity of Industrial Systems

8 Functional Safety and Cybersecurity

8.1. Introduction

8.1.1. Components of operational safety

Cybersecurity issues, and more specifically the cybersecurity of industrial and cyber-physical systems, are relatively new. They have been of concern to designers for less than 20 years for the reasons presented in the Introduction.

On the other hand, ensuring that a system operates reliably and without generating risks for those around it, is an older issue. Approaches to improve system reliability were developed from the Second World War and in the 1960s, during the space conquest. Initially, the causes of failures were mainly mechanical, but then the electronic and programmable electronic aspects became more and more important. Practices were standardized in the 2000s with the publication of standard IEC 61508 (2010). The set of methods used to ensure the proper functioning of a system is part of a discipline called “operational safety” (Figure 8.1), in which we consider the availability (an entity’s ability to provide the required service at a given time) and safety (the requirement not to harm people, the environment, or any other assets during a system’s lifecycle).

These two properties are themselves based on the reliability of the system under consideration. This notion is defined as the ability of an entity to perform a required function, under given conditions, over a given time interval and is measured by the probability that an entity will operate over the interval ...