Trust in Computer Systems and the Cloud

CHAPTER 3Trust Operations and Alternatives

We now have a comprehensive enough understanding of trust as a concept to look more critically at some of the ways that trust can be used. This chapter introduces a number of ways of using trust that we can think of as operations and associated trust components. These can be used alongside some of the foundational primitives that we considered in Chapter 1 to examine—and hopefully design—trust systems. We are also going to consider some alternatives to trust, what entities it may make sense to trust, and some ways of expressing trust.

Trust Actors, Operations, and Components

Before we dive further into trust relationships, we will take a moment to clarify who and what we are talking about when we discuss trust in systems.

• Trustor   The entity with the expectation of actions.
• Trustee   The entity expected to carry out actions.
• System   A set of components—for example, hardware, software, firmware, data, or human users—that can be considered as a single entity for the purposes of one or more specific architectural views of abstractions. A laptop might be considered a system, but so might a distributed blockchain, a nuclear power station, the Bolivian electrical power grid, or a cryptographic accelerator block within a network interface card. One important point is that interfaces with the system should be well-defined and that, from the point of view of an entity (itself possibly a system), communicating with it, the individual components ...