Multiparty Quantum Key Agreement: Architectures, State-of-the-art, and Open Problems

2026-03-03

AI Summary

This work addresses the core challenge in multiparty quantum key agreement (MQKA)—enabling three or more mutually distrustful parties to establish a shared secret key securely and fairly. The authors propose a unified analytical framework structured around a three-axis orthogonal design space defined by network architecture, quantum resources, and security models, moving beyond conventional linear protocol enumeration. This framework systematically categorizes existing MQKA protocols and reveals their intrinsic coupling mechanisms and trade-offs. The study clarifies the dependency between fairness and collusion resistance, identifies critical open problems—including composability, native network integration, and device-independent implementations—and outlines promising directions for the post-NISQ quantum internet, such as hybrid resource utilization, bosonic encoding, and fairness-aware protocol design, accompanied by a strategic deployment roadmap.

Technology Category

• Machine Learning: Quantum Machine Learning
• Multiagent Systems: Mechanism Design
• Game Theory and Economic Paradigms: Fair Division

Application Category

• Security and Privacy: Large-scale security measurements
• Responsible Web: Consent frameworks and practices on the web
• Search and Retrieval-Augmented AI: Web evaluation methodologies and metrics

Abstract

Multiparty quantum key agreement (MQKA) enables $n \geq 3$ mutually distrustful users to establish a shared secret key through collaborative quantum protocols. In this paper, we provide a comprehensive review where we argue that MQKA is best understood as a design space organized along three orthogonal but tightly coupled axes: (1) network architecture, which determines how quantum states flow between participants; (2) quantum resources, which encode the physical degrees of freedom used for implementation; and (3) security model, which defines trust assumptions about devices and infrastructure. Rather than treating MQKA as a linear sequence of isolated protocols, we develop this three-axis perspective to reveal recurrent patterns, sharp trade-offs, and unexplored design spaces. We classify MQKA protocols into structural families, map them to underlying quantum resources, and analyze how different security models shape fairness and collusion resistance. We further identify open challenges in composable security frameworks, network native integration, device-independent implementations, and propose a research roadmap toward hybrid-resource, bosonic-code-encoded, and fairness-aware MQKA suitable for the future quantum internet deployments in the post-NISQ era.

Problem

• Multiparty Quantum Key Agreement
• network architecture
• quantum resources
• security model
• fairness

Innovation

• Multiparty Quantum Key Agreement
• Design Space Framework
• Quantum Network Architecture
• Device-Independent Security
• Bosonic Code Encoding