Pioneering quantum authenticated key agreement through Grover’s algorithm

• Published in: Quantum information processing Vol. 24; no. 10; p. 323
• Main Authors: Chen, Tzung-Her, Lee, Chien-Ding, Chang, Yu-Chieh
• Format: Journal Article
• Language: English
• Published: New York Springer US 30.09.2025; Springer Nature B.V
• Subjects: Agreements; Algorithms; Authentication; Communication; Data Structures and Information Theory; Digital signatures; Mathematical Physics; Physics; Physics and Astronomy; Protocol; Quantum Computing; Quantum cryptography; Quantum Information Technology; Quantum Physics; Search algorithms; Security; Spintronics; Trusted third parties; Verification; Grover search algorithm; Quantum key agreement; Authentication; Decoy photon
• ISSN: 1573-1332; 1570-0755; 1573-1332
• DOI: 10.1007/s11128-025-04942-z

Existing quantum key agreement (QKA) protocols based on Grover’s search algorithm suffer from a critical security vulnerability: the absence of mutual authentication mechanisms between participants. This fundamental flaw enables man-in-the-middle attacks, malicious state injection, and protocol disruption by unauthorized parties. We present the first quantum authenticated key agreement (QAKA) protocol that integrates Grover’s algorithm with comprehensive mutual authentication, addressing the authentication gap in current Grover-based QKA schemes. Our protocol employs a strategically decoy photon insertion mechanism specifically designed for quantum identity verification, combined with a trusted third-party framework that enables both initial authentication and direct mutual verification between communicating parties. Security analysis demonstrates the security against both external eavesdropping and internal authentication attacks.