The survey and analysis on Physical Layer Encryption techniques

Physical Layer Key Generation (PKG) has evolved as a promising technique to circumvent the problems faced by the classical symmetric key production schemes. It exploits channel reciprocity and spatial decorrelation provided by wireless medium. This paper systematically reviews the evolution of PKG technologies, discussing their working principles, performance metrics, and implementations under various scenarios such as slow-fading channels, low SNR, and multi-user environments. With recent advancements introduced—intelligent reflecting surfaces (RIS/STAR-RIS), optimization powered by AI/ML, and their integration with massive MIMO and terahertz communications—chaos, robustness, and scalability enhancements are investigated. Further exploration involves application domains from IoT and healthcare to Industry 4.0 and 6G networks, this focus shifting from proof of feasibility to full-fledged implementation. The concluded findings show that PKG is inclined to become a key security primitive for next-generation wireless systems to enjoin lightweight and efficient friendly key management schemes.