scholarly journals Simple security proofs for continuous variable quantum key distribution with intensity fluctuating sources

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Chenyang Li ◽  
Li Qian ◽  
Hoi-Kwong Lo
Keyword(s):  
Quantum Key Distribution ◽  
Distribution Systems ◽  
Finite Size ◽  
Key Distribution ◽  
Continuous Variable ◽  
Discrete Variable ◽  
Security Proofs ◽  
Security Proof ◽  
Main Technique ◽  
Secret Keys

AbstractDespite tremendous theoretical and experimental progress in continuous variable (CV) quantum key distribution (QKD), the security has not been rigorously established for most current continuous variable quantum key distribution systems that have imperfections. Among these imperfections, intensity fluctuation is one of the principal problems affecting security. In this paper, we provide simple security proofs for continuous variable quantum key distribution systems with intensity fluctuating sources. Specifically, depending on device assumptions in the source, the imperfect systems are divided into two general cases for security proofs. In the most conservative case, we prove the security based on the tagging idea, which is a main technique for the security proof of discrete variable quantum key distribution. Our proofs are simple to implement without any hardware adjustment for current continuous variable quantum key distribution systems. Also, we show that our proofs are able to provide secure secret keys in the finite-size scenario.

scholarly journals Finite-size security of continuous-variable quantum key distribution with digital signal processing

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Takaya Matsuura ◽  
Kento Maeda ◽  
Toshihiko Sasaki ◽  
Masato Koashi
Keyword(s):  
Signal Processing ◽  
Wavelength Division Multiplexing ◽  
Quantum Key Distribution ◽  
Finite Size ◽  
Digital Signal ◽  
Key Distribution ◽  
Continuous Variable ◽  
Wavelength Division ◽  
Security Proof ◽  
Proof Techniques

AbstractIn comparison to conventional discrete-variable (DV) quantum key distribution (QKD), continuous-variable (CV) QKD with homodyne/heterodyne measurements has distinct advantages of lower-cost implementation and affinity to wavelength division multiplexing. On the other hand, its continuous nature makes it harder to accommodate to practical signal processing, which is always discretized, leading to lack of complete security proofs so far. Here we propose a tight and robust method of estimating fidelity of an optical pulse to a coherent state via heterodyne measurements. We then construct a binary phase modulated CV-QKD protocol and prove its security in the finite-key-size regime against general coherent attacks, based on proof techniques of DV QKD. Such a complete security proof is indispensable for exploiting the benefits of CV QKD.

scholarly journals Improving Parameter Estimation of Entropic Uncertainty Relation in Continuous-Variable Quantum Key Distribution

Entropy ◽  
2019 ◽  
Vol 21 (7) ◽  
pp. 652 ◽  
Author(s):  
Ziyang Chen ◽  
Yichen Zhang ◽  
Xiangyu Wang ◽  
Song Yu ◽  
Hong Guo
Keyword(s):  
Parameter Estimation ◽  
Quantum Key Distribution ◽  
Uncertainty Relation ◽  
Finite Size ◽  
Key Distribution ◽  
Continuous Variable ◽  
Modulation Method ◽  
Statistical Fluctuation ◽  
Entropic Uncertainty Relation ◽  
Security Proof

The entropic uncertainty relation (EUR) is of significant importance in the security proof of continuous-variable quantum key distribution under coherent attacks. The parameter estimation in the EUR method contains the estimation of the covariance matrix (CM), as well as the max-entropy. The discussions in previous works have not involved the effect of finite-size on estimating the CM, which will further affect the estimation of leakage information. In this work, we address this issue by adapting the parameter estimation technique to the EUR analysis method under composable security frameworks. We also use the double-data modulation method to improve the parameter estimation step, where all the states can be exploited for both parameter estimation and key generation; thus, the statistical fluctuation of estimating the max-entropy disappears. The result shows that the adapted method can effectively estimate parameters in EUR analysis. Moreover, the double-data modulation method can, to a large extent, save the key consumption, which further improves the performance in practical implementations of the EUR.

scholarly journals Security Analysis of Discrete-Modulated Continuous-Variable Quantum Key Distribution over Seawater Channel

2019 ◽  
Vol 9 (22) ◽  
pp. 4956 ◽  
Author(s):  
Xinchao Ruan ◽  
Hang Zhang ◽  
Wei Zhao ◽  
Xiaoxue Wang ◽  
Xuan Li ◽  
...  
Keyword(s):  
Quantum Key Distribution ◽  
Secure Communication ◽  
Security Analysis ◽  
Finite Size ◽  
Key Distribution ◽  
Continuous Variable ◽  
Heterodyne Detection ◽  
Secret Key ◽  
Transmission Distance ◽  
Better Than

We investigate the optical absorption and scattering properties of four different kinds of seawater as the quantum channel. The models of discrete-modulated continuous-variable quantum key distribution (CV-QKD) in free-space seawater channel are briefly described, and the performance of the four-state protocol and the eight-state protocol in asymptotic and finite-size cases is analyzed in detail. Simulation results illustrate that the more complex is the seawater composition, the worse is the performance of the protocol. For different types of seawater channels, we can improve the performance of the protocol by selecting different optimal modulation variances and controlling the extra noise on the channel. Besides, we can find that the performance of the eight-state protocol is better than that of the four-state protocol, and there is little difference between homodyne detection and heterodyne detection. Although the secret key rate of the protocol that we propose is still relatively low and the maximum transmission distance is only a few hundred meters, the research on CV-QKD over the seawater channel is of great significance, which provides a new idea for the construction of global secure communication network.

Finite-size analysis of continuous-variable quantum key distribution with entanglement in the middle

2019 ◽  
Vol 28 (1) ◽  
pp. 010305 ◽  
Author(s):  
Ying Guo ◽  
Yu Su ◽  
Jian Zhou ◽  
Ling Zhang ◽  
Duan Huang
Keyword(s):  
Quantum Key Distribution ◽  
Finite Size ◽  
Key Distribution ◽  
Continuous Variable ◽  
Size Analysis

scholarly journals High performance frame synchronization for continuous variable quantum key distribution systems

2015 ◽  
Vol 23 (17) ◽  
pp. 22190 ◽  
Author(s):  
Dakai Lin ◽  
Peng Huang ◽  
Duan Huang ◽  
Chao Wang ◽  
Jinye Peng ◽  
...  
Keyword(s):  
Quantum Key Distribution ◽  
High Performance ◽  
Distribution Systems ◽  
Key Distribution ◽  
Continuous Variable ◽  
Frame Synchronization ◽  
Performance Frame

scholarly journals Improved Data Post-Processing in Quantum Key Distribution and Application to Loss Thresholds in device independent QKD

2012 ◽  
Vol 12 (3&4) ◽  
pp. 203-214
Author(s):  
Xiongfeng Ma ◽  
Norbert Lutkenhaus
Keyword(s):  
Data Structure ◽  
Error Correction ◽  
Quantum Key Distribution ◽  
Security Analysis ◽  
Key Distribution ◽  
Post Processing ◽  
Security Proofs ◽  
Security Proof ◽  
Independent Case ◽  
Loss Tolerance

Security proofs of quantum key distribution (QKD) often require post-processing schemes to simplify the data structure, and hence the security proof. We show a generic method to improve resulting secure key rates by partially reversing the simplifying post-processing for error correction purposes. We apply our method to the security analysis of device-independent QKD schemes and of detection-device-independent QKD schemes, where in both cases one is typically required to assign binary values even to lost signals. In the device-independent case, the loss tolerance threshold is cut down by our method from 92.4% to 90.9%. The lowest tolerable transmittance of the detection-device-independent scheme can be improved from 78.0% to 65.9%

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