AI summaryⓘ
The authors studied whether it is possible to tell which kind of quantum communication protocol is being used just by looking at some physical signals, without interfering with the actual quantum data. They tested four different protocols by passively observing parts of the photon signals and used this to create identifiable 'fingerprints' of each protocol. Their experiments showed that these protocols can be recognized with high accuracy, even when only a small portion of the signal is observed. Importantly, their method did not destroy the quantum entanglement, preserving the integrity of the communication. This suggests that quantum networks might be vulnerable to side channel leaks that reveal protocol details without breaking the quantum security itself.
quantum communicationquantum entanglementside channel analysisquantum key distributionoptical tappingphoton detectionprotocol fingerprintingBell inequalitynon-destructive measurementquantum identity authentication
Authors
Lance Young, Contessa Wilburn, Carrie Houston, Blaine Keyton, Marwan Elawady, Mohamed Shaban, Muhammad Ismail
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.