Authenticated multi-user quantum private query using GHZ states
Ying Zhang, Chen‐Ming Bai, Sujuan Zhang
Abstract Quantum private query (QPQ) enables users to extract desired entries from a database without decrypting its content, while simultaneously safeguarding both user query privacy and database security. In this paper, we propose a multi-user QPQ protocol based on Greenberger–Horne–Zeilinger (GHZ) states, which allows two distant users, Alice 1 and Alice 2 , to jointly query the same database entry. The protocol introduces a semi-trusted third party to prepare and distribute the GHZ states, and employs a bidirectional authentication mechanism to ensure the authenticity of the communicating entities. Security analysis demonstrates that the proposed protocol effectively resists both internal and external attacks and exhibits resilience against quantum computing attacks. Compared with existing QPQ schemes, the protocol significantly improves user privacy and database security while supporting multi-user collaborative queries.
Physica Scripta•Jul 3, 2026•1 citation