Enhanced Secrecy in Optical Communication using Speckle from Multiple Scattering Layers

TL;DR

This paper demonstrates that using multiple scattering layers in optical communication creates uncorrelated speckle patterns, significantly enhancing secrecy by preventing interception or decoding of transmitted messages.

Contribution

The study introduces a novel optical secrecy method leveraging speckle correlation analysis across multiple scattering layers, showing no detectable correlation and thus improved security.

Findings

No correlation found between speckle patterns and messages

High number of transmission modes increases security

Method compatible with existing encryption techniques

Abstract

We study the secrecy of an optical communication system with two scattering layers, to hide both the sender and receiver, by measuring the correlation of the intermediate speckle generated between the two layers. The binary message is modulated as spatially shaped wavefronts, and the high number of transmission modes of the scattering layers allows for many uncorrelated incident wavefronts to send the same message, making it difficult for an attacker to intercept or decode the message and thus increasing secrecy. We collect 50,000 intermediate speckle patterns and analyze their correlation distribution using Kolmogorov-Smirnov (K-S) test. We search for further correlations using the K-Means and Hierarchical unsupervised classification algorithms. We find no correlation between the intermediate speckle and the message, suggesting a person-in-the-middle attack is not possible. This method is compatible with any digital encryption method and is applicable for codifications in optical wireless communication (OWC).