Implementation of a Quantum Authentication Protocol Using Single Photons in Deployed Fiber

Area of Science:

• Quantum Information Science
• Cybersecurity
• Quantum Communication Networks

Background:

• Securing quantum communication networks requires robust entity authentication.
• Existing quantum key distribution (QKD) systems need enhanced security measures.
• BB84-type protocols are foundational for quantum key distribution.

Purpose of the Study:

• To propose and experimentally validate a quantum entity authentication (QEA) protocol.
• To ensure seamless integration with BB84-type QKD workflows and current terminal architectures.
• To provide a practical solution for securing quantum communication networks.

Main Methods:

• Developed a QEA protocol resistant to intercept-resend man-in-the-middle (MitM) attacks.
• Utilized weak coherent pulses (WCPs) with decoy-state estimation for practical implementation.
• Mitigated photon-number-splitting (PNS) attacks by bounding single-photon contributions.
• Deployed and tested the protocol over a 20 km fiber link with ~8 dB optical loss.

Main Results:

• The protocol detects MitM impersonation with a characteristic 25% correlation error.
• Rejection probability approaches unity with increasing authentication events.
• Stable operation achieved with quantum bit error rate (QBER) between 1% and 4%.
• Sifted key rate remained constant over time during field tests.

Conclusions:

• The experimental validation provides a basis for integrating physical-layer entity authentication into quantum networks.
• The proposed QEA protocol offers a practical and robust solution for enhancing quantum communication security.
• The protocol's resilience against specific attacks demonstrates its suitability for deployed systems.