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

Area of Science:

• Quantum Information Science
• Telecommunications Security
• Optical Physics

Background:

• Continuous-variable quantum key distribution (CV-QKD) relies on homodyne detectors, essential for distinguishing coherent states.
• Theoretical CV-QKD security assumes detector linearity, which is practically limited by finite linear domains.
• Homodyne detector-blinding attacks exploit this linearity limitation to compromise CV-QKD security.

Purpose of the Study:

• To propose and validate a countermeasure against homodyne detector-blinding attacks in CV-QKD.
• To enhance the practical security of CV-QKD protocols, particularly those with finite-size effects.
• To address the vulnerability arising from the non-ideal linearity of homodyne detectors.

Main Methods:

• Implementing an adjustable optical attenuator with a feedback control structure.
• Estimating optimal attenuation values during CV-QKD data processing.
• Applying real-time feedback of attenuation values to the optical attenuator before the detector.
• Conducting numerical simulations to evaluate the countermeasure's effectiveness.

Main Results:

• The proposed countermeasure effectively mitigates homodyne detector-blinding attacks.
• Real-time feedback ensures the detector operates within its linear domain, preventing saturation.
• The security of Gaussian-modulated coherent state CV-QKD protocols, considering finite-size effects, is maintained.

Conclusions:

• The adjustable optical attenuator with feedback provides a robust defense against detector-blinding attacks.
• This method enhances the practical security and reliability of CV-QKD systems.
• The findings contribute to the secure implementation of quantum communication technologies.