A Cyber-Physical System (CPS) combines resources from both physical and cyberspace. A typical CPS system is like a Water Distribution System (WDS) composed of different sensors, actuators, logical programming controllers, and grid systems. Cloud computing provides on-demand computing services and data, but suffers from latency and security issues between devices. The devices in CPS are power-constrained and perform real-time operations; therefore, authentication of these devices is crucial for ensuring secure communication between the instruments and control room. The lightweight Elliptical Curve Cryptography (ECC) helps to provide authentication between the device and fog-enabled controller rooms. The proposed Hybrid Lightweight Attribute-Based Security Scheme helps to provide authentication and signature verification with significantly less computational and communication overhead. Thus, the model helps to save energy and works in real-time. The model is also tested with a different brain-pool curve list to determine which curve list performs better and faster.