ZTF-SF: a zero-trust blockchain-enabled IIoT framework for secure smart factories

Modern smart factories increasingly rely on Industrial Internet of Things (IIoT) devices for automation and monitoring, expanding the attack surface and exposing limits of traditional perimeter-based security. Zero-trust security addresses this by eliminating implicit trust and continuously verifying every entity and action, while blockchain offers decentralized trust management and tamper-evident auditing. This paper proposes ZTF-SF, a conceptual framework for securing the IIoT-driven manufacturing using zero trust network access and a permissioned consortium blockchain. Blockchain is employed to manage the device identities, enforce trust consistency among components, and record security-played events in unchangeable audit logs. ZTF-SF provides, as part of ZTF IMT, continuous authentication, fine-grained authorization, micro-segmentation, and adaptive monitoring at heterogeneous IIoT devices. A threat model is presented for smart manufacturing and how ZTF-SF reduces various potential attacks known to affect smart manufacturing, like misuse from the inside and multi-stakeholder trust gaps, with decentralized verification and enforcement that can be audited.