Abstract

Physical-layer key distribution is an area of active research due to vulnerabilities in current digital encryption methods, which rely on computational security. We propose and demonstrate a high-speed physical-layer key generation and distribution method based on random mode mixing in multimode optical fibers. We refer to this method as random-channel cryptography (RCC). In RCC, a key is extracted from the channel state of a shared multidimensional reciprocal channel. Projection operators reduce the signal to a single degree of freedom (DOF) for the legitimate users, while the signal is spread over many DOFs anywhere accessible to eavesdroppers. This produces a large asymmetry between the eavesdroppers' and legitimate users' measurement complexities. Furthermore, signal-to-noise ratio analysis reveals that RCC is information-theoretically secure under certain attacks. However, initial demonstrations of RCC offered very low key rate-distance products. A nine orders-of-magnitude increase in the key rate-distance product was demonstrated using techniques from traditional telecommunications, such as high-speed modulation, wavelength-division multiplexing, and advanced modulation formats. Compared to other physical-layer key distribution methods, RCC is easy-to-implement, robust, and offers high security.

Notes

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Graduation Date

2023

Semester

Spring

Advisor

Li, Guifang

Degree

Doctor of Philosophy (Ph.D.)

College

College of Optics and Photonics

Department

Optics and Photonics

Degree Program

Optics and Photonics

Format

application/pdf

Identifier

CFE0009594; DP0027617

URL

https://purls.library.ucf.edu/go/DP0027617

Language

English

Release Date

May 2026

Length of Campus-only Access

3 years

Access Status

Doctoral Dissertation (Campus-only Access)

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