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arXiv:2202.00140 · IEEE International Symposium on Information Theory (ISIT)

High-Dimensional Quantum Conference Key Agreement

Omar Amer, Walter O. Krawec

Published Jun 26, 2022• 3 citations
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Abstract

Quantum Conference Key Agreement (QCKA) protocols are designed to allow multiple parties to agree on a shared secret key, secure against computationally unbounded adversaries. In this paper, we consider a high-dimensional QCKA protocol and prove its information theoretic security against arbitrary, general, attacks in the finite-key scenario. Our proof technique may be useful for other high-dimensional multiparty quantum cryptographic protocols. Finally, we evaluate the protocol in a variety of settings, showing that high-dimensional states can greatly benefit QCKA protocols.

DOI
10.1109/isit50566.2022.9834652

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Quantum Conference Key Agreement (QCKA) protocols are designed to allow multiple parties to agree on a shared secret key, secure against computationally unbounded adversaries. In this paper, we consider a high-dimensional QCKA protocol and prove its information theoretic security against arbitrary, general, attacks in the finite-key scenario. Our proof technique may be useful for other high-dimensional multiparty quantum cryptographic protocols. Finally, we evaluate the protocol in a variety of settings, showing that high-dimensional states can greatly benefit QCKA protocols.
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Abstract A quantum conference key agreement (QCKA) protocol based on differential-phase-shift quantum key distribution is presented, which provides a common secret key for secure communication between more than two parties. In the proposed protocol, one party simultaneously broadcasts a weak coherent pulse train with {0, π} phases to multiple parties that measure the phase differences between adjacent pulses using a delay interferometer followed by photon detectors, and the transmitter and receivers share secret key bits from the coincident counts in the receivers. The system setup and operation are simpler than those of conventional QCKA schemes that use a multipartite quantum entanglement state. The key creation performance is evaluated by considering the eavesdropping probability. The results indicate that the proposed scheme offers better performance than the conventional entanglement-based QCKA system.
In this work, we prove security of a quantum conference key agreement (QCKA) protocol augmented with a classical advantage distillation (CAD) protocol. We derive a proof of security, in the finite key setting, that is able to bound the secure key rate for any general, coherent, attack. We evaluate the performance of the system, showing our result can improve the noise tolerance of the protocol in some, but not all, scenarios. Specifically, our work can improve key rates in network scenarios where users are not located at equal distances, and where there are asymmetries in the error rate between parties.
Quantum conference key agreement (QCKA) enables the unconditional secure distribution of conference keys among multiple participants. Due to challenges in high-fidelity preparation and long-distance distribution of multi-photon entanglement, entanglement-based QCKA is facing severe limitations in both key rate and scalability. Here, we propose a source-independent QCKA scheme utilizing the post-matching method, feasible within the entangled photon pair distribution network. We introduce an equivalent distributing virtual multi-photon entanglement protocol for providing unconditional security proof even in the case of coherent attacks. For the symmetry star network, compared with the previous n -photon entanglement protocol, the conference key rate is improved from O ( η n ) to O ( η 2 ), where η is the transmittance from the entanglement source to one participant. Simulation results show that the performance of our protocol has multiple orders of magnitude advantages in the intercity distance. We anticipate that our approach will demonstrate its potential in the implementation of quantum networks.
Quantum conference key agreement (QCKA) generalises the traditional two-party quantum key distribution (QKD) paradigm to multiple users, enabling them to share a common quantum-safe key. Deriving quantum conference keys from multi-partite entanglement can have significant resource advantages over two-party schemes [1]. Anonymous quantum key agreement (AQCKA) is a related protocol which has been theoretically shown to obtain an even more substantial reduction in network resources when multi-partite entanglement is available and incorporated into the protocol. The addition of anonymity can be useful in circumstances where users require guaranteed secrecy, e.g. for electronic voting, or for whistle blowers.
Quantum conference key agreement (QCKA) enables multiple users to establish a common secret key with information-theoretic security and is regarded as a key primitive for secure communication in future quantum networks. However, practical implementations of QCKA typically suffer from higher noise levels than conventional bipartite quantum key distribution (QKD), making the improvement of the tolerable error threshold an important challenge. Gottesman and Lo proposed two preprocessing procedures for QKD with two-way classical communication, known as the B-step and the P-step, which enhance the tolerable error threshold. In this paper, we analyze the asymptotic security of QCKA with tripartite GHZ states and two measurement bases using two-way classical communication, including multiple B-steps and P-steps. We derive the corresponding secure key rate analytically and demonstrate that iterative B-steps can increase the tolerable error threshold beyond 20%, significantly improving upon the approximately 11% threshold achievable without two-way classical communication and the approximately 15% threshold obtained with only a single B-step. Our results show that two-way classical communication can substantially enhance the robustness of practical QCKA protocols.