Advancing multi-party quantum key agreement protocols: the power of a two-layer approach

Quantum key agreement holds great promise for enabling secure and efficient data transfer in the era of advanced technologies. This paper proposes a novel approach to address the key generation problem by introducing a two-layer multiparty quantum key agreement (TMQKA) protocol based on non-maximally entangled states. The TMQKA protocol generates two layers of keys among multiple users by employing the properties of non-maximally entangled states and local operations. The first layer of keys is established among all users to achieve secure multiparty communication. The second layer of keys is between two neighboring users to ensure point-to-point communication between them. In addition, the analysis demonstrates that the proposed TMQKA protocol satisfies the requirements of correctness, security, and fairness. The unique two-layer structure of TMQKA makes it have a high efficiency. Our work lays the foundation for the establishment of two-layer quantum networks in the future.