Mutual entity authentication of a quantum key distribution network system using authentication qubits

Abstract

Entity authentication is crucial for ensuring secure quantum communication because the identity of the participants in a network must be confirmed before transmitting any confidential information. We propose a practical entity authentication protocol, which uses authentication qubits, for quantum key distribution (QKD) network systems. In this protocol, authentication qubits encoded with pre-shared information are generated and exchanged to verify the legitimacy of each entity. Using the authentication qubit, participants can identify each other with the same level of security as in QKD through the quantum channel. The proposed protocol can be easily integrated into existing QKD systems without additional hardware. In this study, we demonstrate the efficacy of the proposed scheme using a 1 x N QKD network system, and verify its stable operation over a deployed fiber network. In addition, we present a security analysis of the proposed entity authentication protocol and architecture.