Employing Single Photons for Measurement-Device-Independent Quantum Secure Direct Communication With Identity Authentication

Quantum secure direct communication (QSDC) enables secure message transmission without needing pre-shared keys. To enhance the practical reliability of QSDC systems, measurement-device-independent (MDI) protocols have emerged, providing robust security in real-world applications. Despite the advantages of MDI protocols, their implementation has not yet accomplished communication using only single photons which are advantageous due to their ease of preparation and transmission. In this letter, by employing single photons, we propose a novel MDI-QSDC protocol with identity authentication. This protocol achieves mutual identity authentication between the communicating parties, Alice and Bob, enabling authenticated Alice to securely transmit her secret message directly to authenticated Bob. Theoretical analysis demonstrates the protocol is resilient to identity and message security threats. Simulations with practical experimental parameters and efficiency analysis highlight its potential in quantum communication.