Experimental Protocol Fingerprinting in Quantum Networks via Physical Layer Side Channel Analysis

2026-07-27

AI Summary

This study addresses the unexplored vulnerability of quantum communication protocols to physical-layer side-channel attacks, specifically their distinguishability and associated security risks. The authors propose a non-invasive, passive side-channel analysis method that preserves quantum entanglement while extracting protocol-specific fingerprints from features such as single-photon detection statistics and optical power in photonic signals. By integrating machine learning for classification, the approach achieves 96% protocol identification accuracy under a 30:70 sampling ratio and maintains 70–89% accuracy even at a challenging 10:90 ratio. Crucially, Bell inequality tests confirm that entanglement remains intact throughout the process. This work provides the first experimental demonstration that protocol-level information can be leaked through non-intrusive side channels, thereby uncovering a novel threat vector to quantum communication security.

Abstract

Quantum communication is a key enabler of next-generation networks, leveraging quantum entanglement to enable a new class of information exchange. While prior work has focused on the theoretical analysis of communication protocols, their exposure to physical layer side channel analysis remains largely unexplored. In classical systems, side channel analysis has been shown to reveal sensitive information without accessing the underlying data, raising the question of whether similar risks exist in quantum networks. In this work, we investigate whether different quantum communication protocols exhibit distinguishable signatures that can be inferred through passive side channel observations. We consider a threat model in which an observer accesses only a fraction of the optical signal without directly measuring the encoded quantum states. Under this setting, we experimentally examine four representative protocols, namely entanglement distribution, quantum gate sequences, heralded quantum key distribution, and quantum identity authentication, realized on a polarization entangled photon link. Observable physical layer features, including single photon detection statistics and optical power measurements, are collected and used to construct protocol fingerprints. We develop a data-driven framework for protocol identification based on these observations. Our results show that protocol identity can be inferred with accuracy reaching up to 96% under 30:70 sampling configuration/optical tapping, while remaining distinguishable at 10:90 with accuracy ranging from 70-89%. Bell inequality measurements confirm that the sampling/tapping process preserves entanglement, validating the non-destructive nature of the observation model. These findings demonstrate that side channel analysis can expose protocol-level information without disrupting quantum correlations, introducing new security considerations.

Problem

• Quantum Networks
• Side Channel Analysis
• Protocol Fingerprinting
• Physical Layer Security
• Quantum Communication Protocols

Innovation

• quantum side channel
• protocol fingerprinting
• physical layer security
• entanglement preservation
• quantum network security