Physical Layer Security in Multimode Fiber Optical Networks

Stefan Rothe,Eduard Jorswieck,Jürgen W Czarske,Andrew Lonnstrom,Hannes Radner,Nektarios Koukourakis

doi:10.1038/s41598-020-59625-9

Stefan Rothe, Eduard Jorswieck + Show 4 more

Open Access

https://doi.org/10.1038/s41598-020-59625-9

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Abstract

The light propagation through a multimode fiber is used to increase information security during data transmission without the need for cryptographic approaches. The use of an inverse precoding method in a multimode fiber-optic communication network is based on mode-dependent losses on the physical layer. This leads to an asymmetry between legitimate (Bob) and illegitimate (Eve) recipients of messages, resulting in significant SNR advantage for Bob. In combination with dynamic mode channel changes, there are defined hurdles for Eve to reconstruct a sent message even in a worst-case scenario in which she knows the channel completely. This is the first time that physical layer security has been investigated in a fiber optical network based on measured transmission matrices. The results show that messages can be sent securely using traditional communication techniques. The technology introduced is a step towards the development of cyber physical systems with increased security.

Highlights

The amount of exchanged data via internet has increased exponentially in recent years[1]
Experimental studies on physical layer security (PLS) in MMF optical networks are shown for the first time
PLS is a technique in which information security is not achieved by exchanging a cryptographic key, but by exploiting the physical properties of the transmission channel itself

Summary

Introduction

The amount of exchanged data via internet has increased exponentially in recent years[1]. Physical unclonable functions (PUFs) are physical objects that cannot feasibly be copied due to their comprehensive number of degrees of freedom They have been studied as a physical one-time pad[9] and as a secure physical authentication protocol[3,10,11,12], respectively. In applications where PUFs were utilized to create secure authentication, the security relies on the difficulty of cloning the optical response[3], as well as in combination with a low mean photon number[11,12] This physical encryption technique always assumes that Alice and Bob have access to the PUF in an initial calibration step, which is not observed by a possible eavesdropper (e.g. Eve). It uses a cryptographic protocol that employs procedures of quantum mechanics This approach gives two parties of a communication network the possibility to generate a secure key, which is only known to them. This limits the applicability of quantum states in large scaled networks

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