Evaluation of an OPC UA-Based Access Control Enforcement Architecture.

Dynamic access control in industrial systems is becoming a concern of greater importance as a consequence of the increasingly flexible manufacturing systems developed within the Industry 4.0 paradigm. With the shift from control system security design based on implicit trust toward a zero-trust approach, fine grained access control is a fundamental requirement. In this article, we look at an access control enforcement architecture and authorization protocol outlined as part of the Open Process Communication Unified Automation (OPC UA) protocol that can allow sufficiently dynamic and fine-grained access control. We present an implementation, and evaluates a set of important quality metrics related to this implementation, as guidelines and considerations for introduction of this protocol in industrial settings. Two approaches for optimization of the authorization protocol are presented and evaluated, which more than halves the average connection establishment time compared to the initial approach.