  The advent of Industrial IoT (IIoT) along with Cloud computing has brought a
huge paradigm shift in manufacturing industries resulting in yet another
industrial revolution, Industry 4.0. Huge amounts of delay-sensitive data of
diverse nature are being generated which needs to be locally processed and
secured due to its sensitivity. But, the low-end IoT devices are unable to
handle huge computational overheads. Also, the semi-trusted nature of Cloud
introduces several security concerns. To address these issues, this work
proposes a secure Fog-based IIoT architecture by suitably plugging a number of
security features into it and by offloading some of the tasks judiciously to
fog nodes. These features secure the system alongside reducing the trust and
burden on the cloud and resource-constrained devices respectively. We validate
our proposed architecture through both theoretical overhead analysis and
practical experimentation including simulation study and testbed
implementation.
