Practical quantum multiparty signatures using quantum-key-distribution networks

TL;DR

This paper presents a practical, unconditionally secure quantum signature scheme for messages over QKD networks, ensuring authenticity and transferability without relying on computational assumptions.

Contribution

It introduces a novel quantum signature protocol compatible with existing QKD devices, incorporating a two-layer network structure with security against malicious nodes.

Findings

Scheme guarantees unconditional security based on quantum mechanics

Optimized parameters reduce secret key consumption

Compatible with current QKD technology

Abstract

Digital signatures are widely used for providing security of communications. At the same time, the security of currently deployed digital signature protocols is based on unproven computational assumptions. An efficient way to ensure an unconditional (information-theoretic) security of communication is to use quantum key distribution (QKD), whose security is based on laws of quantum mechanics. In this work, we develop an unconditionally secure signature scheme that guarantees authenticity and transferability of arbitrary length messages in a QKD network. In the proposed setup, the QKD network consists of two subnetworks: (i) an internal network that includes the signer and with limitation on the number of malicious nodes and (ii) an external network that has no assumptions on the number of malicious nodes. A consequence of the absence of the trust assumption in the external subnetwork is the necessity of assistance from internal subnetwork recipients for the verification of message-signature pairs by external subnetwork recipients. We provide a comprehensive security analysis of the developed scheme, perform an optimization of the scheme parameters with respect to the secret key consumption, and demonstrate that the developed scheme is compatible with the capabilities of currently available QKD devices.