Two-Layer Multiparty Quantum Key Agreement Protocol with Collective Detection

In a secure communication network, multiparty quantum key agreement (MQKA) is crucial for providing multiple participants with secret keys in a fair manner. To address the needs of both multiparty secure communication and point-to-point secure communication simultaneously, this paper introduces a novel two-layer multiparty quantum key agreement (TMQKA) protocol with collective detection, based on non-maximum entangled states. The first-layer agreement key is established among multiple participants to enable secure multiparty communication. The second-layer agreement key is established between any two participants to enable point-to-point secure communication. The generation of two-layer keys improves the efficiency of the protocol. In addition, we demonstrate that the proposed TMQKA protocol satisfies the requirements of correctness, security, and fairness. This paper presents a theoretical exploration of TMQKA, contributing to the expanding body of research on multiparty quantum cryptography. Our work represents an attempt to develop secure communication protocols for practical applications.