Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Scientific Reports

Practical Security Analysis of Reference Pulses for Continuous-Variable Quantum Key Distribution

Wei Zhao, Ronghua Shi, Duan Huang

Published Dec 3, 2019• 12 citations
Publisher

Abstract

By manipulating the reference pulses amplitude, a security vulnerability is caused by self-reference continuous-variable quantum key distribution. In this paper, we formalize an attack strategy for reference pulses, showing that the proposed attack can compromise the practical security of CVQKD protocol. In this scheme, before the beam splitter attack, Eve intercepts the reference pulses emitted by Alice, using Bayesian algorithm to estimate phase shifts. Subsequently, other reference pulses are re-prepared and resubmitted to Bob. In simulations, Bayesian algorithm effectively estimates the phase drifts and has the high robustness to noise. Therefore, the eavesdropper can bias the excess noise due to the intercept-resend attack and the beam splitter attack. And Alice and Bob believe that their excess noise is below the null key threshold and can still share a secret key. Consequently, the proposed attack shows that its practical security can be compromised by transmitting the reference pulses in the continuous-variable quantum key distribution protocol.

DOI
10.1038/s41598-019-54249-0

Related papers

Phase attack on reference pulses of continuous-variable quantum key distribution with real local oscillators

Biao Huang, Langhua Liu, Yu Wang +2 more

Continuous-variable quantum key distribution (CVQKD) with a real local oscillator (LO) is confronted with new security issues attributed to the reference pulses transmitted together with quantum signals over the insecure quantum channel. This paper proposes a method of phase attack on reference pulses of the CVQKD with real LOs. Under the phase attack, the phase drifts of reference pulses are manipulated by eavesdroppers so that the phase compensation error is increased. Consequently, the secret key rate is reduced because of the imperfect phase compensation for quantum signals. Based on the noise model of imperfect phase compensation, both the parameters of actual transmittance and actual excess noise are deduced from the phase compensation accuracy, and then they are compared with those estimated by training signals. The simulation results show that the secret key rate calculated from the theoretical parameters is consistent with the one estimated by training signals.

•Dec 18, 2019•1 citation

Practical Security of the Continuous-Variable Quantum Key Distribution with Locally-Generated Local Oscillators

Biao Huang, Yongjun Zhu, Pu Tang +2 more

Continuous-variable quantum key distribution (CVQKD) with the local local oscillator (LLO) is confronted with new security problems due to the reference pulses transmitted together with quantum signals over the insecure quantum channel. In this paper, we propose a method of phase attack on reference pulses of the LLO-CVQKD with time-multiplexing. Under this phase attack, the phase drifts of reference pulses are manipulated by eavesdroppers, and then the phase compensation error is increased. Consequently, the secret key rate is reduced due to the imperfect phase compensation for quantum signals. Based on the noise model of imperfect phase compensation, the practical security of LLO-CVQKD under phase attack is analyzed. The simulation results show that the practical security is reduced due to the phase attack, yet it is still tight when system parameters are estimated by training signals.

Journal of Applied Mathematics and Physics•Jan 1, 2019•1 citation

Polarization Attack on Continuous-Variable Quantum Key Distribution with a Local Local Oscillator

Yun Shao, Yan Pan, Heng Wang +6 more

The estimation of phase noise of continuous-variable quantum key distribution protocol with a local local oscillator (LLO CVQKD), as a major process in quantifying the secret key rate, is closely relevant to the intensity of the phase reference. However, the transmission of the phase reference through the insecure quantum channel is prone to be exploited by the eavesdropper (Eve) to mount attacks. Here, we introduce a polarization attack scheme against the phase reference. Presently, in a practical LLO CVQKD system, only part of the phase reference pulses are measured to compensate for the polarization drift of the quantum signal pulses in a compensation cycle due to the limited polarization measurement rate, while the other part of the phase reference pulses are not measured. We show that Eve can control the phase noise by manipulating the polarization direction of the unmeasured phase reference to hide her attack on the quantum signal. Simulations show that Eve can obtain partial or total key rates information shared between Alice and Bob as the transmission distance increases. Improving the polarization measurement rate to 100% or monitoring the phase reference intensity in real-time is of great importance to protect the LLO CVQKD from polarization attack.

Entropy•Jul 18, 2022•9 citations

Practical security of the continuous-variable quantum key distribution with real local oscillators under phase attack

Biao Huang, Yongmei Huang, Zhenming Peng

Continuous-variable quantum key distribution (CVQKD) with a real local oscillator (LO) is confronted with new security problems due to the reference pulses transmitted together with quantum signals over the insecure quantum channel. In this paper, we propose a method of phase attack on reference pulses of the CVQKD with real LOs. Under the phase attack, the phase drifts of reference pulses are manipulated by eavesdroppers, and then the phase compensation error is increased. Consequently, the secret key rate is reduced due to the imperfect phase compensation for quantum signals. Based on the noise model of imperfect phase compensation, the practical security of the CVQKD under phase attack is analyzed. Besides, we propose an effective method to detect the intensity of phase attack, in which the deviation of phase compensation error on quantum signals and that on reference signals are monitored in real time. The simulation results show that the security analysis is accurate and the method of phase attack detection is feasible.

Optics Express•Jul 10, 2019•17 citations

Phase-reference intensity attack on continuous-variable quantum key distribution with a real local oscillator

Yun Shao, Yang Li, Heng Wang +5 more

In practical continuous-variable quantum key distribution system using local local oscillator (LLO CV-QKD), the phase noise related to coherent detection and phase-reference pulse intensity that can be locally calibrated at the receiver side is considered to be trusted noise to improve the performance. However, if the intensity of the phase-reference pulse is not monitored precisely in real-time, a security loophole will be opened for the eavesdropper to launch attacks. To this end, we propose two practical phase-reference pulse intensity attack strategies, where Eve can reduce the trusted phase noise by manipulating the intensity of the phase-reference pulse, thereby hiding her attack on the signal pulse if the total excess noise remains unchanged. The performance of the LLO CV-QKD system under these attacks has been analyzed. We show that precisely monitoring the intensity of the phase-reference pulse in real-time is an essential countermeasure to prevent the proposed attacks. Moreover, an intensity-monitoring scheme for the phase-reference pulse is proposed to strengthen the security of the practical LLO CV-QKD system and make the trusted phase noise model more robust.

arXiv:2111.09542•Nov 18, 2021•1 citation

Phase noise estimation using Bayesian inference for continuous-variable quantum key distribution

Wei Zhao, Ying Guo, Ling Zhang +1 more

Excess noise induced by the phase drifts is a serious impairment for the continuous-variable quantum key distribution with locally generated local oscillator scheme, which is recently proposed to avoid the side channel attacks due to the transmitted local oscillator. Theoretical and experimental studies on the phase estimation have been widely reported, while two frequency-locked laser sources are indispensable to achieve quantum coherent detection. Moreover, the self-referenced phase estimation scheme requires to propagate the strong reference pulse through optical fiber, which opens a security loophole through the manipulation of the reference pulse amplitude. Based on the theoretical security and Bayes' theorem, we propose a phase estimation protocol, which does not require propagating the strong reference pulse for performing phase estimation. Compared to the other related work, the protocol can avoid the security problem caused by strong reference pulse. Moreover, this algorithm is an iterative progress for each of experiment to obtain the phase estimation and its uncertainty. We hope the proposed scheme could further promote the performance of continuous-variable quantum key distribution.

Optics Express•Jan 22, 2019•10 citations
By manipulating the reference pulses amplitude, a security vulnerability is caused by self-reference continuous-variable quantum key distribution. In this paper, we formalize an attack strategy for reference pulses, showing that the proposed attack can compromise the practical security of CVQKD protocol. In this scheme, before the beam splitter attack, Eve intercepts the reference pulses emitted by Alice, using Bayesian algorithm to estimate phase shifts. Subsequently, other reference pulses are re-prepared and resubmitted to Bob. In simulations, Bayesian algorithm effectively estimates the phase drifts and has the high robustness to noise. Therefore, the eavesdropper can bias the excess noise due to the intercept-resend attack and the beam splitter attack. And Alice and Bob believe that their excess noise is below the null key threshold and can still share a secret key. Consequently, the proposed attack shows that its practical security can be compromised by transmitting the reference pulses in the continuous-variable quantum key distribution protocol.
Continuous-variable quantum key distribution (CVQKD) with a real local oscillator (LO) is confronted with new security issues attributed to the reference pulses transmitted together with quantum signals over the insecure quantum channel. This paper proposes a method of phase attack on reference pulses of the CVQKD with real LOs. Under the phase attack, the phase drifts of reference pulses are manipulated by eavesdroppers so that the phase compensation error is increased. Consequently, the secret key rate is reduced because of the imperfect phase compensation for quantum signals. Based on the noise model of imperfect phase compensation, both the parameters of actual transmittance and actual excess noise are deduced from the phase compensation accuracy, and then they are compared with those estimated by training signals. The simulation results show that the secret key rate calculated from the theoretical parameters is consistent with the one estimated by training signals.
Continuous-variable quantum key distribution (CVQKD) with the local local oscillator (LLO) is confronted with new security problems due to the reference pulses transmitted together with quantum signals over the insecure quantum channel. In this paper, we propose a method of phase attack on reference pulses of the LLO-CVQKD with time-multiplexing. Under this phase attack, the phase drifts of reference pulses are manipulated by eavesdroppers, and then the phase compensation error is increased. Consequently, the secret key rate is reduced due to the imperfect phase compensation for quantum signals. Based on the noise model of imperfect phase compensation, the practical security of LLO-CVQKD under phase attack is analyzed. The simulation results show that the practical security is reduced due to the phase attack, yet it is still tight when system parameters are estimated by training signals.
The estimation of phase noise of continuous-variable quantum key distribution protocol with a local local oscillator (LLO CVQKD), as a major process in quantifying the secret key rate, is closely relevant to the intensity of the phase reference. However, the transmission of the phase reference through the insecure quantum channel is prone to be exploited by the eavesdropper (Eve) to mount attacks. Here, we introduce a polarization attack scheme against the phase reference. Presently, in a practical LLO CVQKD system, only part of the phase reference pulses are measured to compensate for the polarization drift of the quantum signal pulses in a compensation cycle due to the limited polarization measurement rate, while the other part of the phase reference pulses are not measured. We show that Eve can control the phase noise by manipulating the polarization direction of the unmeasured phase reference to hide her attack on the quantum signal. Simulations show that Eve can obtain partial or total key rates information shared between Alice and Bob as the transmission distance increases. Improving the polarization measurement rate to 100% or monitoring the phase reference intensity in real-time is of great importance to protect the LLO CVQKD from polarization attack.
Continuous-variable quantum key distribution (CVQKD) with a real local oscillator (LO) is confronted with new security problems due to the reference pulses transmitted together with quantum signals over the insecure quantum channel. In this paper, we propose a method of phase attack on reference pulses of the CVQKD with real LOs. Under the phase attack, the phase drifts of reference pulses are manipulated by eavesdroppers, and then the phase compensation error is increased. Consequently, the secret key rate is reduced due to the imperfect phase compensation for quantum signals. Based on the noise model of imperfect phase compensation, the practical security of the CVQKD under phase attack is analyzed. Besides, we propose an effective method to detect the intensity of phase attack, in which the deviation of phase compensation error on quantum signals and that on reference signals are monitored in real time. The simulation results show that the security analysis is accurate and the method of phase attack detection is feasible.
In practical continuous-variable quantum key distribution system using local local oscillator (LLO CV-QKD), the phase noise related to coherent detection and phase-reference pulse intensity that can be locally calibrated at the receiver side is considered to be trusted noise to improve the performance. However, if the intensity of the phase-reference pulse is not monitored precisely in real-time, a security loophole will be opened for the eavesdropper to launch attacks. To this end, we propose two practical phase-reference pulse intensity attack strategies, where Eve can reduce the trusted phase noise by manipulating the intensity of the phase-reference pulse, thereby hiding her attack on the signal pulse if the total excess noise remains unchanged. The performance of the LLO CV-QKD system under these attacks has been analyzed. We show that precisely monitoring the intensity of the phase-reference pulse in real-time is an essential countermeasure to prevent the proposed attacks. Moreover, an intensity-monitoring scheme for the phase-reference pulse is proposed to strengthen the security of the practical LLO CV-QKD system and make the trusted phase noise model more robust.
Excess noise induced by the phase drifts is a serious impairment for the continuous-variable quantum key distribution with locally generated local oscillator scheme, which is recently proposed to avoid the side channel attacks due to the transmitted local oscillator. Theoretical and experimental studies on the phase estimation have been widely reported, while two frequency-locked laser sources are indispensable to achieve quantum coherent detection. Moreover, the self-referenced phase estimation scheme requires to propagate the strong reference pulse through optical fiber, which opens a security loophole through the manipulation of the reference pulse amplitude. Based on the theoretical security and Bayes' theorem, we propose a phase estimation protocol, which does not require propagating the strong reference pulse for performing phase estimation. Compared to the other related work, the protocol can avoid the security problem caused by strong reference pulse. Moreover, this algorithm is an iterative progress for each of experiment to obtain the phase estimation and its uncertainty. We hope the proposed scheme could further promote the performance of continuous-variable quantum key distribution.