I. Introduction
The network systems of cyber and physical elements are mainly composed of cyber–physical system (CPS) that interact in a response cycle with the assistance of human involvement, interactions, and utilization. The demand for CPS has gained wide attention in various fields owing to a focus on data communication, data handling, and the integration of information systems [1]. CPS is currently used in a variety of areas, such as transportation, healthcare, and automotive systems, directly impacting our daily lives. A CPS is designed to generate complex systems by connecting individual components. Data are commonly gathered using a visual sensor and transferred to the control system through a network without any human intervention [2]. However, CPS is incurring significant security challenges as the cyber and physical worlds become more interconnected. This means that both the systems and interconnections among CPS subsystems are becoming more complex. A CPS is composed of three layers: 1) a perception layer; 2) a transmission layer; and 3) an application layer the most interactive [1], [3].