Dual-Layer Security: Integration of Simulated QKD and Experimental PLS for VLC

This letter proposes a novel dual-layer security framework for visible light communication (VLC) by integrating the BB84 quantum key distribution (QKD) protocol with beam directivity-based physical layer security (PLS). This combined approach enhances resilience against eavesdropping threats, offering stronger security compared to individual techniques, particularly in highly secure environments. The analysis indicates that in the first layer, simulated in <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathrm{MATLAB}^{\circledR} $ </tex-math></inline-formula>, the QKD system with multiphoton source benefits from an increased average number of photons, improving the secret key fraction and enhancing resistance to quantum channel attenuation. However, this advantage comes at the expense of heightened vulnerability to photon number splitting (PNS) attacks. To mitigate this, the second layer, location-based PLS, which is implemented on an experimental testbed, restricts Eve’s access to the VLC data channel by leveraging beam directivity. Within the limitations defined by the controlled indoor setup, the obtained results demonstrate that even under a strong PNS attack, Eve’s best bit error rate (BER) remains higher at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2.4\times 10 ^{\mathbf {-2}}$ </tex-math></inline-formula> compared to Bob’s worst BER at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3.7\times 10 ^{\mathbf {-3}}$ </tex-math></inline-formula>, ensuring secure communication.