Physical Layer Security in Optical Networks

Abstract

A numerical investigation was conducted using a MATLAB-based model to explore the performance of an optical layer encryption technique for physical layer security (PLS). The PLS technique employs a secret analogue key generated by digital signal processing (DSP) and digital-to-analogue conversion (DAC). An investigation was conducted to observe the impact of noise induced in the key due to timing jitter in key generation function. It was observed that there is a strong relationship between the tolerance to timing jitter and the absolute value of dispersive elements -D1. In order to reduce the impact of the timing jitter, using a dispersive element with lower values will result in better tolerance to timing jitter, but this will also reduce the level of security, this trade-off is fully investigated. It is shown that a modulation index (MI) of 0.80 prevents illegal data recovery, whilst tolerating a maximum combined total jitter of 5% UIrms. There is also a trade-off allowing the maximum tolerated timing jitter to increase if the system’s power budget is decreased.