This project aims to accelerate the deployment of security measures for cyber-physical systems (CPSs). A framework is proposed that combines anomaly identification approaches, which emphasizes on the development of decentralized cyber-attack monitoring and diagnostic-like components, with robust control countermeasure to improve reliability and maintain system functionality. Within this framework, the investigators will (1) implement hybrid observers and active attack detection methods exploiting system vulnerabilities; and (2) develop and integrate cyber-attack control countermeasure at the physical system level to guarantee functionality and resiliency in the presence of identified and unidentified threats. Specifically, this project focuses on applications to connected vehicle (CV) systems where vehicles are capable of sharing information via dedicated short range communication network, with the goal of improving fuel efficiency and avoiding collision. The project's final objective would be to create a cyber-secure vehicle connectivity paradigm that incorporates cyber-attack detection algorithms and executes integrated fault-tolerant countermeasures at the vehicle level to support vehicle system resiliency and accelerate the future commercialization of automated vehicles. The research solutions of this project will impact safety, security and reliability of networked CPSs by helping accelerate the adoption of threat identification and attack resilient control countermeasures at the system and network level. The specific application to connected and automated vehicles should lead to a future market acceptance of these vehicle technologies with a potential improvement in traffic conditions, vehicle and personal safety, and energy consumption. This project involves interdisciplinary research in cyber security for the development of more secure, scalable and reliable future networked CPSs. It proposes to conduct fundamental research on a model-based computational strategy that includes: 1) implement advanced threat models in a hybrid systems framework; 2) identify system and communication vulnerabilities especially in the dedicated short range communication network (DSRC) for CVs; 3) derive hybrid observer based cyber-attack detection algorithms based on stochastic quantized models and event triggered estimation; 4) establish active attack detection methods based on system vulnerabilities; 5) develop control counter measures for each CPS based on game theory and robust control methods; 6) derive control algorithms against malicious agents in the CV to avoid vehicle collisions; 7) develop computationally fast and distributed algorithms for the above six objectives; and 8) evaluate through simulation and experimental validation the capabilities and impact on the vehicle of the proposed strategies.