  In Industry 4.0, Cyber-Physical Systems (CPS) are formed by components, which
are interconnected with each other over the Internet of Things (IoT). The
resulting capabilities of sensing and affecting the physical world offer a vast
range of opportunities, yet, at the same time pose new security challenges. To
address these challenges there are various IoT Frameworks, which offer
solutions for managing and controlling IoT-components and their interactions.
In this regard, providing security for an interaction usually requires
performing additional security-related tasks (e.g. authorisation, encryption,
etc.) to prevent possible security risks. Research currently focuses more on
designing and developing these frameworks and does not satisfactorily provide
methodologies for evaluating the resulting costs of providing security. In this
paper we propose an initial approach for measuring the resulting costs of
providing security for interacting IoT-components by using a Security Cost
Modelling Framework. Furthermore, we describe the necessary building blocks of
the framework and provide an experimental design showing how it could be used
to measure security costs at runtime.
