Physical layer security using optical steganography and encoding techniques in optical networks

Date of Award


Degree Type


Degree Name

Master of Science


School of Science

First Advisor

Professor Craig Valli

Second Advisor

Dr Ahmed Ibrahim

Field of Research Code

080503, 100506, 100507


Physical layer security using optical signal processing in optical networks has been researched over recent decades to preserve data transmission confidentiality and privacy. One of the solutions that has been studied is optical steganography, which is used to conceal the data transmission in a host signal. However, only hiding the signal is not enough. Therefore, this research aims to demonstrate optical steganography using encoding techniques as cyber security solutions in the physical layer to guarantee privacy and confidentiality of the data transmitted.

Laboratory experiments and software simulations were used to demonstrate the feasibility of the solutions proposed. Further, with an experimental approach using a quantitative method, the independent variables were manipulated to test the viability of the proposed circuits, and their effect measured and recorded for data analysis.

This research has proposed two optical network solutions. First, an Amplified Spontaneous Emission (ASE) noise source was used to create a stealth channel using variable optical time delay and polarisation control creating a two-factor technique to encode the data transmitted. This signal is then hidden in the additional ASE noise and the public channel for transmission. Second, a Spectral-Amplitude Code (SAC) Optical Code- Division Media-Access (OCDMA) with multiple user channels using fibre Brag grating (FBG) as encoders of the optical steganography to create the stealth channel, which is also hidden in the ASE noise, and the public channel. Polarisation control and Dispersion Compensation Fibre (DCF) are also used for creating a three-factor encoding technique for an optical security solution. Particularly, the ASE noise is a side effect present in most of the fibre optic communication networks, which aids in hiding the presence of the data transmission, thus the presence of the ASE noise in the signal is not suspicious.

This research has made the following contributions in the field of cyber security solutions in the physical layer: 1) demonstrated feasibility in combining different encoding techniques with optical steganography; 2) three-factor security solutions requirement, which are employed to enhance confidentiality and privacy of specific applications; 3) presented cyber security solutions in the physical layer as effective alternatives to software and protocol encryption.

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