A unified versus integrated approach
Both safety and security engineering approaches analyze risks, impose limitations on the system through design and implementation constraints, and produce protective measures. However, they do so by leveraging a unique set of methods, guidelines, and tools. While it is self-evident that a disjointed approach to safety and security engineering is inefficient and results in significant reworks, the choice between a unified and an integrated approach is not so obvious. Briefly, a unified approach is one in which the methods and work products become unified to address both aspects of safety and security. For example, the HARA would be extended to incorporate hazards originating from malicious events, the FMEA would be expanded to consider malicious causes of failure modes, and so on. Similarly, rather than producing a separate set of safety and security requirements, those would be unified to address both aspects of the system. This would continue throughout...