Secrecy through Precoding: A Novel Physical Layer Encryption Scheme with Optimal PAPR

Traditional cryptographic methods ensure data confidentiality through sophisticated and complex key management and encryption protocols. However, such approaches may be ill-suited for scenarios with limited coordination capabilities, such as military communications or the Internet of Things (IoT); Physical Layer Encryption (PLE) then offers a complementary or alternative solution by securing information directly at the signal level. Among existing PLE techniques, masking strategies have shown considerable promise. Nonetheless, many of these techniques suffer from drawbacks such as high Peak-To-Average Power Ratio (PAPR), rely on the eavesdropper's channel knowledge, or lack of adaptability to diverse wireless environments. In this paper, we propose a novel PLE technique that overcomes these limitations. Our approach achieves optimal PAPR by design, requires no knowledge of the eavesdropper's channel state information, and is applicable to all flat fading channels. Additionally, the method incorporates continuous randomization in signal generation, enhancing resistance to brute-force attacks. These features collectively make our solution a robust and practical candidate for secure wireless communication at the physical layer. Extensive simulations confirm the effectiveness and reliability of the proposed approach under various channel conditions.