Chaos Masking via Invertible Optical Transform within the Security Strategy Framework

We propose a chaos masking scheme whereby an invertible transformation performed by the time domain fractional Fourier transform (FrFT) is utilized. The chaotic phase noise is transformed onto the intensity axis by the FrFT., thus masks the intensity modulated messages. The proposed architecture achieves physical-layer security enhancement through asynchronous chaos modulation, bypassing the explicit synchronization constraints inherent in conventional chaotic encryption paradigms. By varying the control parameters of the FrFT with an external pseudo random binary sequence (PRBS), certain attacks against the FrFT can be immuned. The FrFT parameters and the PRBS are covered by the chaotic phase noise signal which make the eavesdropper difficult to crack the system. Decoupling chaotic entropy generation from optical transmission layers allows independent optimization of broadband photonic noise sources, while enabling plug-and-play security module integration through standardized FrFT operator interfaces.