I. Introduction
The main focus of the cyber–physical systems (CPSs) is to realize the evolution from “traditional and rigid approaches” into “decentralized structures,” which aims to implement the “Industry 4.0” as well as the “Industrial Internet visions” [1]. Thus, the deployment of CPS in an industrial scenario becomes very crucial aspect and it needs adequate mechanisms for enabling the high readiness of such systems for the “industrial usage.” Several cyber attacks can be mounted by an attacker in the CPS communication layer apart from the threat of failing physical infrastructure. Moreover, in a cloud-based CPS environment, the Internet of Things (IoT)-enabled smart devices, gateway nodes acting as access points, fog, and cloud servers communicate over insecure channels. This poses several potential threats in the Industrial CPS (ICPS) environment, for instance “replay,” “Man-in-The-Middle (MiTM),” “impersonation,” “privileged insider,” “physical smart devices capture,” and “ephemeral secret leakage (ESL)” attacks. This suggests design of a robust security protocol in an ICPS environment.