EAQKD: Entanglement-Based Authenticated Quantum Key Distribution

TL;DR

This paper presents Entanglement-Based Authenticated Quantum Key Distribution (EAQKD), a novel protocol that addresses critical security and practical limitations in quantum cryptographic key exchange and provides a rigorously analyzed engineering reference for secure key distribution in future quantum communication networks.

Abstract

The promise of unconditional security in the Quantum Key Distribution (QKD) depends on the availability of an authenticated classical channel. However, practical implementations often overlook this requirement or rely on computational assumptions that compromise long-term security. To overcome these challenges, this paper presents Entanglement-Based Authenticated Quantum Key Distribution (EAQKD), a novel protocol that addresses critical security and practical limitations in quantum cryptographic key exchange. Our approach integrates quantum entanglement distribution with information-theoretic authentication. We evaluate EAQKD's performance through a comprehensive discrete-event simulation framework modeled on realistic channel characteristics and experimental device parameters. Our modeling incorporates parameters from practical quantum optics setups, including SPDC entanglement sources, superconducting nanowire detectors, and fiber channel imperfections. Our results show quantum bit error rates consistently below the 11% security threshold (ranging from 1.86% at 10 km to 9.27% at 200 km), with secure key rates achieving $1.12 \times 10^5$ bits/s at short distances and maintaining practical rates of 9.8 bits/s at 200 km. When integrated with quantum repeater architectures, our analysis projects that EAQKD can extend secure communication beyond 500 km while providing information-theoretic security guarantees. Comparative analysis against the BB84, E91, and Twin-Field QKD protocols demonstrates EAQKD's superior balance of security, practical performance, and implementation robustness. This work advances quantum cryptography by providing a rigorously analyzed engineering reference for secure key distribution in future quantum communication networks.

Figures (8)

• Figure 1: Comprehensive workflow of the EAQKD protocol. The diagram highlights the five operational phases: (1) Entanglement Generation and optional purification, (2) Quantum Distribution with active compensation, (3) Asymmetric Measurement ($p_z=0.9$), (4) Authenticated Classical Post-Processing using Wegman-Carter authentication and strictly separate error checks, and (5) Key Update/Output. The Bell parameter $S$ is utilized solely as a source diagnostic tool.
• Figure 2: Sensitivity analysis: SKR and QBER vs. attenuation and repeater parameters. Dashed lines mark security thresholds.
• Figure 3: Secure key rate vs. distance. Solid: model prediction. Dotted: measured means with 1$\sigma$ error bars (10 runs). Dashed: repeaterless (PLOB) bound.
• Figure 4: Bell parameter $S$ vs. distance. Solid: model including dark counts and depolarizing noise. Horizontal dashed: classical limit $S=2$.
• Figure 5: Real (left) and imaginary (right) parts of reconstructed density matrix at 50 km; fidelity to $|\psi^{-}\rangle$: $0.962 \pm 0.007$.