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arXiv:2407.15761

Fully Passive Quantum Conference Key Agreement

Jinjie Li, Wenyuan Wang, H. F. Chau

Published Jul 22, 2024• 0 citations
arXivHTMLPDF

Abstract

Quantum Conference Key Agreement (CKA) provides a secure method for multi-party communication. A recently developed interference-based prepare-and-measure quantum CKA possesses the advantages of measurement-device-independence, namely, being immune to side-channels from the detector side. Besides, it achieves good key rate performance, especially for high-loss channels, due to the use of single photon interference. Meanwhile, several fully passive QKD schemes have been proposed, which eliminate all side channels from the source modulation side. We extend the fully passive idea to an interference-based CKA, which has a high level of implementation security for many-user communication.

DOI
10.48550/arxiv.2407.15761

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Quantum Conference Key Agreement (CKA) provides a secure method for multi-party communication. A recently developed interference-based prepare-and-measure quantum CKA possesses the advantages of measurement-device-independence, namely, being immune to side-channels from the detector side. Besides, it achieves good key rate performance, especially for high-loss channels, due to the use of single photon interference. Meanwhile, several fully passive QKD schemes have been proposed, which eliminate all side channels from the source modulation side. We extend the fully passive idea to an interference-based CKA, which has a high level of implementation security for many-user communication.
Quantum cryptography is a major ingredient of the future quantum internet that promises various secure communication tasks. Quantum conference key agreement (CKA) is an important cryptographic primitive of quantum cryptography, which provides the conference key among multiple users simultaneously. However, quantum CKA is currently far from practical application due to the low conference key rate. Here, we propose a quantum CKA protocol of three users with information-theoretic security. Our protocol only requires phase-randomized weak coherent sources and threshold single-photon detectors, and is anticipated to be experimentally demonstrated over 600 km under current technology. Our scheme can be widely implemented in the approaching large-scale quantum network.
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Quantum cryptography is anticipated to be a major ingredient of future quantum internet that promises various secure communication tasks. Quantum conference key agreement (CKA) is an important cryptographic primitives of quantum cryptography, which provides the unconditionally secure conference key among multiple users simultaneously. However, it is far from practical application and, more pessimistically, the conference key rate has recently been shown to be limited by Greenberger-Horne-Zeilinger distribution capacity of quantum network. Here, we propose, surprisingly, a quantum CKA of three users to beat the repeaterless capacity even under coherent attacks. Besides, our protocol only requires the phase-randomized weak coherent sources and threshold single-photon detectors, thus can be experimentally demonstrated over 500 km fiber under current technology. Our new type of protocol paves the way towards large-scale quantum CKA network of future quantum internet.
Abstract Quantum secret sharing (QSS) and conference key agreement (CKA) provide efficient encryption approaches for realizing multi-party secure communication, which are essential components of quantum networks. In this work, a practical, scalable, verifiable ( k , n ) threshold continuous variable QSS protocol secure against eavesdroppers and dishonest players are proposed and demonstrated. The protocol does not require preparing the laser source by each player and phase locking of independent lasers. The parameter evaluation and key extraction can be accomplished by only the dealer and the corresponding player. By using the multiple sideband modulation, a single heterodyne detector can extract the information of multiple players. The practical security of the system is considered. The system is versatile, it can support the CKA protocol by only modifying the classic post-processing and requiring no changes to the underlying hardware architecture. By implementing the QSS and CKA protocols with five parties over 25 km (55 km) single-mode fibers, a key rate of 0.0061 (7.14 × 10 −4 ) bits per pulse is observed. The results significantly reduces the system complexity and paves the way for the practical applications of QSS and CKA with efficient utilization of resources and telecom technologies.
Abstract Quantum conference key agreement (CKA) enables key sharing among multiple trusted users with information-theoretic security. Currently, the key rates of most quantum CKA protocols suffer from the limit of the total efficiency among quantum channels. Inspired by the coherent one-way and twin-field quantum key distribution (QKD) protocols, we propose a quantum CKA protocol of three users. Exploiting coherent states with intensity 0 and μ to encode logic bits, our protocol can break the limit. Additionally, the requirements of phase randomization and multiple intensity modulation are removed in our protocol, making its experimental demonstration simple.