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Journal of Engineering and Innovation

การศกษาประสทธภาพการประมวลผลกำเนดรหสลบสวนหลงในระบบการกระจายกญแจ รหสลบเชงควอนตมผานอากาศแบบพวพน

Patcharapong Treeviriyanupab, Paramin Sangwongngam

Published Jun 1, 2024• 0 citations
OpenAlex

Abstract

This paper presents the design and development of practical post-processing software for a general quantum key distribution system. The proposed algorithms consist of three main contributions: 1) channel parameter estimation for quantum bit error rates by a random key sampling method, 2) information reconciliation using rate-adaptive LDPC codes, that collaborate with identical key confirmation by employing a polynomial-based hash function, and 3) privacy amplification performed by a universal hash function, where the binary information is randomly chosen to construct the Toeplitz matrix corresponding to the condition of a secure secret key rate. The proposed post-processing algorithms were implemented and tested in an entangled quantum key distribution experiment based on the BBM92 protocol over a 11-meter free-space quantum channel link. The experiment was conducted over 100 cycles and was able to generate the average sifted key rate of 1,109.08 bits per second. The efficiency of the proposed algorithms enabled two legitimate parties to generate the identical secret key according to the information-theoretic security principles, where the average estimated quantum bit error rate was 2.0127%, the average efficiency of information reconciliation was 1.1919, and the average final secret key rate was 428.42 bits per second. The proposed algorithms could be used in the industrial quantum key distribution systems based on a discrete-variable protocol by optimizing the input parameters of the post-processing procedure, especially for high-speed applications.

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การประมาณคาชองสญญาณดวยภาวะนาจะเปนสงสดสำหรบการไกลเกลยความผดพลาดแบบปรบอตราเขารหสเหมาะสมกบการกระจายกญแจรหสลบเชงควอนตม

พัชรพงษ์ ตรีวิริยานุภาพ, ธราธร พรมสะอาด

การกระจายกุญแจรหัสลับเชิงควอนตัมถือเป็นหนึ่งในเทคโนโลยีความปลอดภัยด้านการสื่อสาร โดยอาศัยหลักกลศาสตร์ควอนตัมเพื่อกำเนิดและแลกเปลี่ยนข้อมูลกุญแจรหัสลับระหว่างคู่สื่อสารให้มีความปลอดภัยสูงสุดสำหรับระบบวิทยาการรหัสลับ ซึ่งต้องอาศัยกระบวนการไกล่เกลี่ยความผิดพลาดเพื่อจุดประสงค์ในการยืนยันความถูกต้องของข้อมูลกุญแจรหัสลับระหว่างคู่สื่อสารให้มีค่าที่ตรงกัน ในบทความนี้ นำเสนอวิธีการประมาณค่าอัตราความผิดพลาดของช่องสัญญาณเชิงควอนตัมบนพื้นฐานของการประมาณค่าภาวะน่าจะเป็นสูงสุดจากชุดข้อมูลซินโดรมในระหว่างขั้นตอนการไกล่เกลี่ยความผิดพลาดสำหรับการปรับค่าอัตราการเข้ารหัสให้เหมาะสมกับความผิดพลาดของบิตข้อมูลกุญแจเชิงควอนตัมที่เกิดขึ้นในแต่ละช่วงเวลาด้วยรหัสตรวจสอบพาริตี้แบบความหนาแน่นต่ำ ตลอดจนการนำมาประยุกต์ใช้แทนขั้นตอนการเปิดเผยบิตข้อมูลกุญแจบางส่วนที่สูญเสียไปในการประมาณค่าความผิดพลาดแบบดั้งเดิม นำไปสู่ผลลัพธ์ของขนาดบิตข้อมูลกุญแจที่เพิ่มสูงขึ้น โดยจากการวิเคราะห์และทดสอบผลพบว่า วิธีการที่นำเสนอให้ความแม่นยำในการประมาณค่าอัตราความผิดพลาดครอบคลุมเงื่อนไขของการกระจายกุญแจรหัสลับเชิงควอนตัม นำไปสู่การเพิ่มประสิทธิภาพการไกล่เกลี่ยความผิดพลาดที่สูงขึ้นทั้งในด้านความปลอดภัยและอัตราการกำเนิดกุญแจรหัสลับ สนับสนุนการประยุกต์ใช้งานจริงในระบบการกระจายกุญแจรหัสลับเชิงควอนตัมความเร็วสูงQuantum Key Distribution (QKD), one of the communication security technologies, employs the properties of quantum mechanics to guarantee and exchange the perfectly-secured key generation between two legitimate parties for cryptographic purposes. The reconciliation process is required to correct the transmission error after the distribution of quantum objects. In this paper, the channel parameter estimation is proposed to estimate the error rate in the quantum channel by using the Maximum-Likelihood Estimation (MLE) based on the syndrome information for rate-adaptive reconciliation. The specific Low-Density Parity-Check (LDPC) codes are adapted to optimize their coding rates responding to the possible cases of error in QKD. The proposed method can be applied to avoid wasting sample keys in the traditional channel estimation, and led to increase the final secret key length. The simulation results show an accuracy of the estimated quantum bit error rate (QBER) for covering the range in QKD system. The gain of rate-adaptive reconciliation based on MLE confirms an improvement in the reconciliation efficiency that significantly impacts on the achievable secret key generation rate for high QKD throughput applications.

The Journal of King Mongkut s University of Technology North Bangkok•Nov 1, 2016•0 citations

Sampling Rate Optimization for LDPC-Based Information Reconciliation Protocol in QKD

Vladimir Morozov, Oleg Olegovich Evsutin, Nikita Yarygin

Quantum Key Distribution (QKD) is a promising field in modern cryptography where the security of key information is guaranteed by the laws of quantum mechanics. One of the key stages in QKD protocols is error estimation and reconciliation in the secret key. This procedure requires the transmission of a certain number of secret key bits over a public channel. Such transmission leads to disclosing these bits to a potential eavesdropper. The fraction of disclosed bits—the sampling rate-largely depends on the chosen approach for preliminary error estimation in the channel. This work is devoted to the optimization of the sampling rate for an LDPC code from the $\mathbf{5 G}$ standard. The results of our experiments show that for a QBER below 0.2 and key lengths of 264, 528, 792, and 1056 bits, it is necessary to disclose no more than $18 \%, 11 \%, 10 \%$, and $7 \%$ of the key bits for error estimation, respectively. Furthermore, the proposed algorithm allows for similar optimization for any information reconciliation protocols and actual quantum bit error rates.

International Symposium on Problems of Redundancy in Information and Control Systems (REDUNDANCY)•Nov 5, 2025•1 citation
This paper presents the design and development of practical post-processing software for a general quantum key distribution system. The proposed algorithms consist of three main contributions: 1) channel parameter estimation for quantum bit error rates by a random key sampling method, 2) information reconciliation using rate-adaptive LDPC codes, that collaborate with identical key confirmation by employing a polynomial-based hash function, and 3) privacy amplification performed by a universal hash function, where the binary information is randomly chosen to construct the Toeplitz matrix corresponding to the condition of a secure secret key rate. The proposed post-processing algorithms were implemented and tested in an entangled quantum key distribution experiment based on the BBM92 protocol over a 11-meter free-space quantum channel link. The experiment was conducted over 100 cycles and was able to generate the average sifted key rate of 1,109.08 bits per second. The efficiency of the proposed algorithms enabled two legitimate parties to generate the identical secret key according to the information-theoretic security principles, where the average estimated quantum bit error rate was 2.0127%, the average efficiency of information reconciliation was 1.1919, and the average final secret key rate was 428.42 bits per second. The proposed algorithms could be used in the industrial quantum key distribution systems based on a discrete-variable protocol by optimizing the input parameters of the post-processing procedure, especially for high-speed applications.
An effective post-processing algorithm is essential for achieving high rates of secret key generation in quantum key distribution. This work introduces an approach to quantum key distribution post-processing by integrating the three main steps into a unified procedure: syndrome-based error estimation, rate-adaptive reconciliation, and subblock confirmation. The proposed scheme employs low-density parity-check codes to estimate the quantum bit error rate using the syndrome information, and to optimize the channel coding rates based on the Slepian-Wolf coding scheme for the rate-adaptive method. Additionally, this scheme incorporates polynomial-based hash verification in the subblock confirmation process. The numerical results show that the syndrome-based estimation significantly enhances the accuracy and consistency of the estimated quantum bit error rate, enabling effective code rate optimization for rate-adaptive reconciliation. The unified approach, which integrates rate-adaptive reconciliation with syndrome-based estimation and subblock confirmation, exhibits superior efficiency, minimizes practical information leakage, reduces communication rounds, and guarantees convergence to the identical key. Furthermore, the simulations indicate that the secret key throughput of this approach achieves the theoretical limit in the context of a BB84 quantum key distribution system.
In a continuous-variable quantum key distribution (CV-QKD) system, the computation speed of the post-processing procedure, including information reconciliation (IR) and privacy amplification (PA), inevitably affects the practical secret key rate. IR and PA can be implemented in parallel using low-density parity-check (LDPC) codes and hash functions, respectively. We achieve high-speed hardware-accelerated post-processing procedure for Gaussian symbols on a field-programmable gate array (FPGA) by taking advantage of its superior parallel processing ability. To this end, the sum-product algorithm decoders and a modified LDPC codes construction algorithm adapted to FPGA's characteristics are developed and employed. Two different structures including multiplexing and non-multiplexing are designed to achieve the trade-off between the speed and area of FPGAs, so that an optimal scheme can be adopted according to the requirement of a practical system. Simulation results show that the maximum throughput can reach 100 M symbols/s. We verified the correctness of the post-processing procedures when implemented on the Xilinx VC709 evaluation board, which is populated with the Virtex-7 XC7VX690T FPGA and provided some possible solutions to obtain better performance when more advanced FPGAs are available. The scheme can be applied readily for real-time key extraction and effectively reduce power consumption of the CV-QKD system.
Quantum key distribution (QKD), based on quantum mechanics, enables unconditionally secure key exchange even against adversaries with unlimited computing power. As the core of QKD post-processing, information reconciliation (IR) and privacy amplification (PA) ensure key consistency and security by correcting errors and removing leaked information. With the trend toward miniaturized and chip-based QKD systems, post-processing modules require highly integrated designs. FPGAs offer an ideal solution due to their low cost, power efficiency, and flexibility. This paper presents an FPGA-based QKD post-processing architecture using a polar codes-based appending IR algorithm, achieving reconciliation efficiency better than 1.1 under Eµ≥ 0.06 and Rm= 4. A convolution-structured Toeplitz hash module is developed for PA, supporting 53.13 Mbps data rate and 26.45 Mbps key rate with RPA= 0.5. The complete system is implemented on a Xilinx XCKU040 FPGA. Experimental results show support for 176.58 Mbps input, 36.59 Mbps real-time processing, and 17.56 Mbps key output, demonstrating strong performance and engineering suitability. The design features high integration and portability, offering a practical hardware solution for efficient QKD post-processing.
Post-processing is a significant step in quantum key distribution (QKD), which is used for correcting the quantum-channel noise errors and distilling identical corrected keys between two distant legitimate parties. Efficient error reconciliation protocol, which can lead to an increase in the secure key generation rate, is one of the main performance indicators of QKD setups. In this paper, we propose a multi-low-density parity-check codes based reconciliation scheme, which can provide remarkable perspectives for highly efficient information reconciliation. By testing our approach through data simulation, we show that the proposed scheme combining multi-syndrome-based error rate estimation allows for a more accurate estimation of the error rate as compared with random sampling and single-syndrome estimation techniques before the error correction, as well as a significant increase in the efficiency of the procedure without compromising security and sacrificing reconciliation efficiency.
การกระจายกุญแจรหัสลับเชิงควอนตัมถือเป็นหนึ่งในเทคโนโลยีความปลอดภัยด้านการสื่อสาร โดยอาศัยหลักกลศาสตร์ควอนตัมเพื่อกำเนิดและแลกเปลี่ยนข้อมูลกุญแจรหัสลับระหว่างคู่สื่อสารให้มีความปลอดภัยสูงสุดสำหรับระบบวิทยาการรหัสลับ ซึ่งต้องอาศัยกระบวนการไกล่เกลี่ยความผิดพลาดเพื่อจุดประสงค์ในการยืนยันความถูกต้องของข้อมูลกุญแจรหัสลับระหว่างคู่สื่อสารให้มีค่าที่ตรงกัน ในบทความนี้ นำเสนอวิธีการประมาณค่าอัตราความผิดพลาดของช่องสัญญาณเชิงควอนตัมบนพื้นฐานของการประมาณค่าภาวะน่าจะเป็นสูงสุดจากชุดข้อมูลซินโดรมในระหว่างขั้นตอนการไกล่เกลี่ยความผิดพลาดสำหรับการปรับค่าอัตราการเข้ารหัสให้เหมาะสมกับความผิดพลาดของบิตข้อมูลกุญแจเชิงควอนตัมที่เกิดขึ้นในแต่ละช่วงเวลาด้วยรหัสตรวจสอบพาริตี้แบบความหนาแน่นต่ำ ตลอดจนการนำมาประยุกต์ใช้แทนขั้นตอนการเปิดเผยบิตข้อมูลกุญแจบางส่วนที่สูญเสียไปในการประมาณค่าความผิดพลาดแบบดั้งเดิม นำไปสู่ผลลัพธ์ของขนาดบิตข้อมูลกุญแจที่เพิ่มสูงขึ้น โดยจากการวิเคราะห์และทดสอบผลพบว่า วิธีการที่นำเสนอให้ความแม่นยำในการประมาณค่าอัตราความผิดพลาดครอบคลุมเงื่อนไขของการกระจายกุญแจรหัสลับเชิงควอนตัม นำไปสู่การเพิ่มประสิทธิภาพการไกล่เกลี่ยความผิดพลาดที่สูงขึ้นทั้งในด้านความปลอดภัยและอัตราการกำเนิดกุญแจรหัสลับ สนับสนุนการประยุกต์ใช้งานจริงในระบบการกระจายกุญแจรหัสลับเชิงควอนตัมความเร็วสูงQuantum Key Distribution (QKD), one of the communication security technologies, employs the properties of quantum mechanics to guarantee and exchange the perfectly-secured key generation between two legitimate parties for cryptographic purposes. The reconciliation process is required to correct the transmission error after the distribution of quantum objects. In this paper, the channel parameter estimation is proposed to estimate the error rate in the quantum channel by using the Maximum-Likelihood Estimation (MLE) based on the syndrome information for rate-adaptive reconciliation. The specific Low-Density Parity-Check (LDPC) codes are adapted to optimize their coding rates responding to the possible cases of error in QKD. The proposed method can be applied to avoid wasting sample keys in the traditional channel estimation, and led to increase the final secret key length. The simulation results show an accuracy of the estimated quantum bit error rate (QBER) for covering the range in QKD system. The gain of rate-adaptive reconciliation based on MLE confirms an improvement in the reconciliation efficiency that significantly impacts on the achievable secret key generation rate for high QKD throughput applications.
Quantum Key Distribution (QKD) is a promising field in modern cryptography where the security of key information is guaranteed by the laws of quantum mechanics. One of the key stages in QKD protocols is error estimation and reconciliation in the secret key. This procedure requires the transmission of a certain number of secret key bits over a public channel. Such transmission leads to disclosing these bits to a potential eavesdropper. The fraction of disclosed bits—the sampling rate-largely depends on the chosen approach for preliminary error estimation in the channel. This work is devoted to the optimization of the sampling rate for an LDPC code from the 5G\mathbf{5 G}5G standard. The results of our experiments show that for a QBER below 0.2 and key lengths of 264, 528, 792, and 1056 bits, it is necessary to disclose no more than 18%,11%,10%18 \%, 11 \%, 10 \%18%,11%,10%, and 7%7 \%7% of the key bits for error estimation, respectively. Furthermore, the proposed algorithm allows for similar optimization for any information reconciliation protocols and actual quantum bit error rates.