Defending Against the Homodyne Detector-Blinding Attack on Continuous-Variable Quantum Key Distribution Using an Adjustable Optical Attenuator

A homodyne detector, which is also a common element in current telecommunication, is a core component of continuous-variable quantum key distribution (CV-QKD) since it is considered the simplest setup for the distinguishing of coherent states with minimum error. However, the theoretical security of...

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Main Authors: Yijun Wang, Yanyan Li, Wenqi Jiang, Ying Guo
Format: Article
Language:English
Published: MDPI AG 2025-06-01
Series:Entropy
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Online Access:https://www.mdpi.com/1099-4300/27/6/631
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author Yijun Wang
Yanyan Li
Wenqi Jiang
Ying Guo
author_facet Yijun Wang
Yanyan Li
Wenqi Jiang
Ying Guo
author_sort Yijun Wang
collection DOAJ
description A homodyne detector, which is also a common element in current telecommunication, is a core component of continuous-variable quantum key distribution (CV-QKD) since it is considered the simplest setup for the distinguishing of coherent states with minimum error. However, the theoretical security of CV-QKD is based on the assumption that the responses of the homodyne detector are always linear with respect to the input, which is impossible in practice. In the real world, a homodyne detector has a finite linear domain, so the linearity assumption is broken when the input is too large. Regarding this security vulnerability, the eavesdropper Eve can perform the so-called homodyne detector-blinding attack by saturating the homodyne detector and then stealing key information without being detected by the legitimate users. In this paper, we propose a countermeasure for the homodyne detector-blinding attack by using an adjustable optical attenuator with a feedback structure. Specifically, we estimate the suitable attenuation value in the data processing of CV-QKD and feed it back to the adjustable optical attenuator before the detector in real time. Numerical simulation shows that the proposed countermeasure can effectively defend against homodyne detector-blinding attacks and ensure the security of the Gaussian-modulated coherent state protocol with finite-size effect.
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spelling doaj-art-3617e9b9c9654e73835e18d8cf2c2dcd2025-08-20T03:27:07ZengMDPI AGEntropy1099-43002025-06-0127663110.3390/e27060631Defending Against the Homodyne Detector-Blinding Attack on Continuous-Variable Quantum Key Distribution Using an Adjustable Optical AttenuatorYijun Wang0Yanyan Li1Wenqi Jiang2Ying Guo3School of Automation, Central South University, Changsha 410083, ChinaSchool of Automation, Central South University, Changsha 410083, ChinaSchool of Automation, Central South University, Changsha 410083, ChinaSchool of Automation, Central South University, Changsha 410083, ChinaA homodyne detector, which is also a common element in current telecommunication, is a core component of continuous-variable quantum key distribution (CV-QKD) since it is considered the simplest setup for the distinguishing of coherent states with minimum error. However, the theoretical security of CV-QKD is based on the assumption that the responses of the homodyne detector are always linear with respect to the input, which is impossible in practice. In the real world, a homodyne detector has a finite linear domain, so the linearity assumption is broken when the input is too large. Regarding this security vulnerability, the eavesdropper Eve can perform the so-called homodyne detector-blinding attack by saturating the homodyne detector and then stealing key information without being detected by the legitimate users. In this paper, we propose a countermeasure for the homodyne detector-blinding attack by using an adjustable optical attenuator with a feedback structure. Specifically, we estimate the suitable attenuation value in the data processing of CV-QKD and feed it back to the adjustable optical attenuator before the detector in real time. Numerical simulation shows that the proposed countermeasure can effectively defend against homodyne detector-blinding attacks and ensure the security of the Gaussian-modulated coherent state protocol with finite-size effect.https://www.mdpi.com/1099-4300/27/6/631homodyne detector-blinding attackcontinuous-variable quantum key distributionadjustable optical attenuatorfeedback structure
spellingShingle Yijun Wang
Yanyan Li
Wenqi Jiang
Ying Guo
Defending Against the Homodyne Detector-Blinding Attack on Continuous-Variable Quantum Key Distribution Using an Adjustable Optical Attenuator
Entropy
homodyne detector-blinding attack
continuous-variable quantum key distribution
adjustable optical attenuator
feedback structure
title Defending Against the Homodyne Detector-Blinding Attack on Continuous-Variable Quantum Key Distribution Using an Adjustable Optical Attenuator
title_full Defending Against the Homodyne Detector-Blinding Attack on Continuous-Variable Quantum Key Distribution Using an Adjustable Optical Attenuator
title_fullStr Defending Against the Homodyne Detector-Blinding Attack on Continuous-Variable Quantum Key Distribution Using an Adjustable Optical Attenuator
title_full_unstemmed Defending Against the Homodyne Detector-Blinding Attack on Continuous-Variable Quantum Key Distribution Using an Adjustable Optical Attenuator
title_short Defending Against the Homodyne Detector-Blinding Attack on Continuous-Variable Quantum Key Distribution Using an Adjustable Optical Attenuator
title_sort defending against the homodyne detector blinding attack on continuous variable quantum key distribution using an adjustable optical attenuator
topic homodyne detector-blinding attack
continuous-variable quantum key distribution
adjustable optical attenuator
feedback structure
url https://www.mdpi.com/1099-4300/27/6/631
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AT wenqijiang defendingagainstthehomodynedetectorblindingattackoncontinuousvariablequantumkeydistributionusinganadjustableopticalattenuator
AT yingguo defendingagainstthehomodynedetectorblindingattackoncontinuousvariablequantumkeydistributionusinganadjustableopticalattenuator