Trust in Computer Systems and the Cloud

CHAPTER 12Trust Domains

Although starting a conversation with an IT security or cybersecurity practitioner by talking about trust domains is likely to gain a nod of recognition, the concept is not common in the field. Despite that, the book has been converging on the domain as a core concept, one that offers major benefits when considering trust models, architectural frameworks, and approaches to implementation. In Chapter 3, we defined trust domains thus:

Trust domains are sets of entities or components that can be considered to form a single unit from the point of view of a trust relationship. All entities share and are subject to the same set of policies. Such a trust relationship must—as with all trust relationships—be bounded by context(s).

There are times when a system—one of the other concepts central to this book—does not provide a unit of abstraction that is large enough for complex trust and security architectures. Before we discuss exactly what we have in mind, let us compare two other similarly named constructs: trusted system domains and trust frameworks.

• Trusted system domains   The Trusted Computing Group defines a trusted systems domain as follows:

  A logical grouping containing infrastructure assets, service providers (operators), users, applications and information where a trusted context has been established and governed by a consistent set of operational and security policies. ¹

  This definition shares our concept that all entities or components are governed ...