Enhancing Security in Cyber Physical Systems through Policy Based Trust Management against Deception Attack V.Kanchana Devi Assistant Professor School of Computing Science and Engineering VIT –Chennai Campus, Chennai-600 127 Email: kanchanadevi@vit.ac.in R.Ganesan Associate Professor School of Computing Science and Engineering VIT –Chennai Campus, Chennai-600 127 Email: ganesan.r@vit.ac.in Abstract-The World is moving towards invisible computers, Ubiquitous Computing (any information everywhere), Pervasive Computing (which combines current network technology with wireless computing), Ambient Intelligence (which refers to electronic environments that are sensitive and responsive to the presence of people), and Traditional Embedded System (which is a closed system, not only in the sense of closed physical locations or dedicated hardware, but also closed with respect to the boundaries, where CPS (Cyber Physical Systems) is an open system which integrate computing and communication with monitoring and/or control of entities in physical world.CPS is used in several applications like Automotive electronics, Avionics, Medical systems, Forestry machines, Logistics, Autonomous Vehicles, and Smart Structures. These are all “Critical Systems”, the failure of the system will harm the people who depend on it. Some challenges in CPS are low power, standard interface of sensors, low cost and high accuracy terminal devices and security. A system without security is like bank without locks. “Trust Management” plays an important role in security of CPS, since it is an open system. Trust Management is a dynamic concept which changes depending on the application. Trust is related to the authentication, authorization which comes under the hard side of trust. And also competence, reliability, integrity, timeliness, accuracy which comes under soft side of trust. Secured data or information that can be trusted. This paper mainly focuses on the trustworthiness of a sensor and controller, where the trust depends on the reliability of the data sent by them. The Policy Based Trust Management is used to identify the false information sent from sensors/controllers by calculating the weightage of the data integrity. This ensures the truthfulness of the sensor/controller in the CPS. Keywords: Cyber Physical system, Security, Trust Management, Data Integrity I. INTRODUCTION Cyber–physical system (CPS) is a new system which has cyber capabilities in the physical world. The difference between a regular control system or an embedded system and CPS is re- configurability, scalability, complexity. And also CPS has intelligence in sensors and actuators. Cyber capabilities are embedded in every physical component, and each networked. CPS is called as system-of-systems because it changes the physical system to include human, infrastructure, and platform. The resulting systems-of-systems are networked and dynamic, with highly complexity, the one who makes policies should be educated in safety, reliability, and security challenges of cyber– physical interactions [4]. In some smart environment, people with physical disabilities receive healthcare services any time for any event, in a more secure way while their dear ones are not nearby. When abnormality is reported by BAN, Smart Home systems send information and other relevant data through the network (local controller) to nearby healthcare which can offer required response, and service. Usually CPS gathers data from the physical environment using sensors and feed the sensor data into controller, which make decisions. The main difficulty of such systems is highly dynamic in nature. The middleware which is currently present cannot handle the dynamic nature of CPS. Thus, the CPS is leading to a 3 rd generation of control systems. There will be evolution in the technology of control system to implement such kind of distributed systems. The CPS is the future and future is the CPS like Embedded is the future and the future is embedded.