Secure and practical multiparty quantum digital signatures

TL;DR

This paper introduces a practical multiparty quantum digital signature protocol that enhances security, efficiency, and scalability, enabling more feasible quantum communication networks with multiple users.

Contribution

It presents a novel multiparty QDS framework based on six-state encoding, reducing quantum channels and improving data utilization, suitable for networks with more than two receivers.

Findings

Quantum channels scale linearly with user number

Data utilization efficiency scales linearly with detection probability

Protocol supports secure multiparty message signing

Abstract

Quantum digital signatures (QDSs) promise information-theoretic security against repudiation and forgery of messages. Compared with currently existing three-party QDS protocols, multiparty protocols have unique advantages in the practical case of more than two receivers when sending a mass message. However, complex security analysis, numerous quantum channels and low data utilization efficiency make it intractable to expand three-party to multiparty scenario. Here, based on six-state non-orthogonal encoding protocol, we propose an effective multiparty QDS framework to overcome these difficulties. The number of quantum channels in our protocol only linearly depends on the number of users. The post-matching method is introduced to enhance data utilization efficiency and make it linearly scale with the probability of detection events even for five-party scenario. Our work compensates for the absence of practical multiparty protocols, which paves the way for future QDS networks.