Enabling Zero-Touch Certificate Management in Modular Plants through Overlay Networks

Increasing regulatory pressure elevate the need to manage device certificates at field level. In modular plants, the operator typically integrates only a module-level interface, breaking the implicit assumption of direct connectivity between field devices and plant public key infrastructure found in current solutions. This paper investigates whether overlay networks can provide an application-layer substrate for decentralized, zero-touch certificate management inside modules. Classical overlays are evaluated, and three are selected for a proof of concept assessing resource efficiency and feasibility for automation systems. Results demonstrate that overlays offer a viable, protocol-independent foundation for certificate management in modular plants.