Evaluation of quantum key distribution systems against injection-locking attacks

While ideal quantum key distribution (QKD) systems are well-understood, practical implementations face various vulnerabilities, such as side-channel attacks resulting from device imperfections. Current security proofs for decoy-state BB84 protocols either assume uniform phase randomization of Alice’...

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Bibliographic Details
Main Authors: Jerome Wiesemann, Fadri Grünenfelder, Ana Blázquez Coído, Nino Walenta, Davide Rusca
Format: Article
Language:English
Published: AIP Publishing LLC 2025-06-01
Series:APL Photonics
Online Access:http://dx.doi.org/10.1063/5.0260685
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Summary:While ideal quantum key distribution (QKD) systems are well-understood, practical implementations face various vulnerabilities, such as side-channel attacks resulting from device imperfections. Current security proofs for decoy-state BB84 protocols either assume uniform phase randomization of Alice’s signals, which is compromised by practical limitations and attacks like injection locking, or rely on a (partially) characterized phase distribution. This work presents an experimental method to characterize the phase de-randomization from injection locking using a heterodyne detection setup, providing a lower bound on the degree of isolation required to protect QKD transmitters against injection-locking attacks. The methods presented are source-agnostic and can be used to evaluate general QKD systems against injection-locking attacks.
ISSN:2378-0967