Securing Optical Wireless Communication: A Cryptographic Approach for Li-Fi Networks

Li-Fi (Light Fidelity) has emerged as a revolutionary optical wireless communication (OWC) technology that uses visible light to transmit data at high speed, offering a compelling alternative to conventional RF-based systems, especially in environments sensitive to electromagnetic interference and those demanding high-density connectivity. Despite the inherent physical security advantage that visible light beams cannot penetrate walls, Li-Fi remains vulnerable to practical threats such as eavesdropping, interception, and sophisticated signal manipulation through channel leakage, reflection, and ambient light noise, which necessitates robust, network-layer security mechanisms. Addressing this critical gap, this research proposes a novel hybrid cryptographic framework specifically designed to be lightweight and scalable for the resource-constrained nature of OWC devices. The framework systematically combines the robust, high-throughput capabilities of the Advanced Encryption Standard (AES) for efficient bulk data encryption with the low-power, compact key size security of Elliptic Curve Cryptography (ECC) for efficient session key exchange, authentication, and non-repudiation. The proposed system ensures data confidentiality, integrity, and authentication between the transmitter (LED-based) and receiver (photodiode-based) nodes within a Li-Fi network, providing end-to-end security that is essential for mission-critical applications. Novel contributions include a lightweight key management protocol tailored to the dynamic and typically line-of-sight visible light links, and a detailed power consumption analysis of the cryptographic operations confirming its suitability for energy-efficient IoT Li-Fi applications. Experimental simulations, conducted on a realistic Li-Fi channel model incorporating signal-to-noise ratio degradation, demonstrate that the encryption overhead is minimal ($<8\%$), which is highly competitive, while simultaneously maintaining a high network throughput efficiency of $94.5\%$. Furthermore, the proposed hybrid cryptosystem is rigorously proven to achieve robust resistance against modern cryptanalytic attacks, including differential analysis, man-in-the-middle attacks, and brute-force key search, thereby establishing a new, feasible security benchmark for secure data transmission across practical Li-Fi deployments and laying the foundation for integrating advanced cryptographic features into future OWC standards.