scholarly journals Adaptive low density parity check encoder for a complete free space optics/continuous variable-quantum key distribution system using commercially available off-the-shelf devices for variable throughput network considering dynamical atmospheric turbulence levels

2018 ◽  
Vol 64 (5) ◽  
pp. 478
Author(s):  
Josue Lopez
Keyword(s):  
Atmospheric Turbulence ◽  
Distribution System ◽  
Quantum Key Distribution ◽  
Continuous Variable ◽  
Free Space Optics ◽  
Parity Check ◽  
Secret Key ◽  
Space Optics ◽  
Low Density Parity Check ◽  
Commercial Network

 In this paper, an adaptive LDPC encoder for complete FSO/CV-QKD system using a COTS device for emulated dynamical atmospheric turbulence levels is presented. The experimental and emulation results show the maximum and minimal final secret key rates of  105 Kbps and 10 Kbps, respectively, for minimal and maximal throughput in a commercial network, 30 Mbps and 90 Mbps, respectively. Our proposal presents an adequate performance for weak and moderate atmospheric turbulence levels and a suitable option for improve the using of QKD systems.

scholarly journals A novel error correction protocol for continuous variable quantum key distribution

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Kadir Gümüş ◽  
Tobias A. Eriksson ◽  
Masahiro Takeoka ◽  
Mikio Fujiwara ◽  
Masahide Sasaki ◽  
...  
Keyword(s):  
Error Correction ◽  
Quantum Key Distribution ◽  
Ldpc Codes ◽  
Key Distribution ◽  
Continuous Variable ◽  
Early Termination ◽  
Parity Check ◽  
Secret Key ◽  
Ldpc Decoder ◽  
And Performance

AbstractReconciliation is a key element of continuous-variable quantum key distribution (CV-QKD) protocols, affecting both the complexity and performance of the entire system. During the reconciliation protocol, error correction is typically performed using low-density parity-check (LDPC) codes with a single decoding attempt. In this paper, we propose a modification to a conventional reconciliation protocol used in four-state protocol CV-QKD systems called the multiple decoding attempts (MDA) protocol. MDA uses multiple decoding attempts with LDPC codes, each attempt having fewer decoding iteration than the conventional protocol. Between each decoding attempt we propose to reveal information bits, which effectively lowers the code rate. MDA is shown to outperform the conventional protocol in regards to the secret key rate (SKR). A 10% decrease in frame error rate and an 8.5% increase in SKR are reported in this paper. A simple early termination for the LDPC decoder is also proposed and implemented. With early termination, MDA has decoding complexity similar to the conventional protocol while having an improved SKR.

scholarly journals High Efficiency Continuous-Variable Quantum Key Distribution Based on ATSC 3.0 LDPC Codes

Entropy ◽  
2020 ◽  
Vol 22 (10) ◽  
pp. 1087 ◽  
Author(s):  
Kun Zhang ◽  
Xue-Qin Jiang ◽  
Yan Feng ◽  
Runhe Qiu ◽  
Enjian Bai
Keyword(s):  
Computational Complexity ◽  
Quantum Key Distribution ◽  
Rapid Development ◽  
Ldpc Codes ◽  
Key Distribution ◽  
Continuous Variable ◽  
Parity Check ◽  
Secret Key ◽  
Information Reconciliation ◽  
Transmission Distance

Due to the rapid development of quantum computing technology, encryption systems based on computational complexity are facing serious threats. Based on the fundamental theorem of quantum mechanics, continuous-variable quantum key distribution (CVQKD) has the property of physical absolute security and can effectively overcome the dependence of the current encryption system on the computational complexity. In this paper, we construct the spatially coupled (SC)-low-density parity-check (LDPC) codes and quasi-cyclic (QC)-LDPC codes by adopting the parity-check matrices of LDPC codes in the Advanced Television Systems Committee (ATSC) 3.0 standard as base matrices and introduce these codes for information reconciliation in the CVQKD system in order to improve the performance of reconciliation efficiency, and then make further improvements to final secret key rate and transmission distance. Simulation results show that the proposed LDPC codes can achieve reconciliation efficiency of higher than 0.96. Moreover, we can obtain a high final secret key rate and a long transmission distance through using our proposed LDPC codes for information reconciliation.

Information reconciliation for QKD

2011 ◽  
Vol 11 (3&4) ◽  
pp. 226-238
Author(s):  
David Elkouss ◽  
Jesus Martinez-Mateo ◽  
Vicente Martin
Keyword(s):  
Quantum Key Distribution ◽  
Key Agreement ◽  
Information Leakage ◽  
Error Rates ◽  
Parity Check ◽  
Random String ◽  
Secret Key ◽  
Information Reconciliation ◽  
Low Density Parity Check ◽  
Secret Key Agreement

Quantum key distribution (QKD) relies on quantum and classical procedures in order to achieve the growing of a secret random string ---the key--- known only to the two parties executing the protocol. Limited intrinsic efficiency of the protocol, imperfect devices and eavesdropping produce errors and information leakage from which the set of measured signals ---the raw key--- must be stripped in order to distill a final, information theoretically secure, key. The key distillation process is a classical one in which basis reconciliation, error correction and privacy amplification protocols are applied to the raw key. This cleaning process is known as information reconciliation and must be done in a fast and efficient way to avoid cramping the performance of the QKD system. Brassard and Salvail proposed a very simple and elegant protocol to reconcile keys in the secret-key agreement context, known as \textit{Cascade}, that has become the de-facto standard for all QKD practical implementations. However, it is highly interactive, requiring many communications between the legitimate parties and its efficiency is not optimal, imposing an early limit to the maximum tolerable error rate. In this paper we describe a low-density parity-check reconciliation protocol that improves significantly on these problems. The protocol exhibits better efficiency and limits the number of uses of the communications channel. It is also able to adapt to different error rates while remaining efficient, thus reaching longer distances or higher secure key rate for a given QKD system.

scholarly journals Multiedge-type low-density parity-check codes for continuous-variable quantum key distribution

2021 ◽  
Vol 103 (6) ◽  
Author(s):  
Hossein Mani ◽  
Tobias Gehring ◽  
Philipp Grabenweger ◽  
Bernhard Ömer ◽  
Christoph Pacher ◽  
...  
Keyword(s):  
Quantum Key Distribution ◽  
Key Distribution ◽  
Continuous Variable ◽  
Low Density ◽  
Parity Check ◽  
Low Density Parity Check ◽  
Parity Check Codes

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.

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