ABSTRACT. Structured systems security economics provides a conceptual framework, inspired by macroeconomic models of trade-offs and mathematical systems models, for analysing the structure of security architectures, their policy constraints, and their interactions with users. In this paper, we explore the dynamics of structured systems security economics by considering the representation and functionality of Actors in the framework. We show how a simple representation of Actors ’ preferences is sufficient to understand the security dynamics of the system and support utility calculations that inform design and investment decisions. Overall, the framework is intended to facilitate the design and implementation of trustworthy security systems.