Protecting Distributed Blockchain with Twin-Field Quantum Key Distribution: A Quantum Resistant Approach

Abstract

Quantum computing provides the feasible multi-layered security challenges to classical blockchain systems. Whereas, quantum-secured blockchains relied on quantum key distribution (QKD) to establish secure channels can address this potential threat. This paper presents a scalable quantum-resistant blockchain architecture designed to address the connectivity and distance limitations of the QKD integrated quantum networks. By leveraging the twin-field (TF) QKD protocol within a measurement-device-independent (MDI) topology, the proposed framework can optimize the infrastructure complexity from quadratic to linear scaling. This architecture effectively integrates information-theoretic security with distributed consensus mechanisms, allowing the system to overcome the fundamental rate-loss limits inherent in traditional point-to-point links. The proposed scheme offers a theoretically sound and feasible solution for deploying large-scale and long-distance consortium.

Figures (8)

• Figure 1: Quantitative comparison of physical link complexity. The red line illustrates the quadratic growth ($\mathrm{O}(N^2)$) of required fiber links in a traditional BB84 mesh network, utilizing the formula $L = N(N-1)/2$. The blue line demonstrates the linear scaling ($\mathrm{O}(N)$) of the proposed TF-QKD star topology ($L=N$). For a network of 100 nodes, the star topology reduces the link requirement by approximately 98%, significantly enhancing scalability.
• Figure 2: Schematic overview of the proposed quantum-resistant blockchain architecture.(a) The hybrid network topology decouples the physical quantum layer from the logical classical layer. TNs connect to a central URN solely for TF-QKD interference, while consensus communications occur over a P2P classical mesh. (b) The four-phase operational workflow: Phase 1 performs continuous key stratification into Evidence Keys ($K_{evid}$) and Consensus Keys ($K_{cons}$); Phase 2 employs $K_{evid}$ for Wegman-Carter authenticated transaction submission; Phase 3 executes decentralized BFT consensus using $K_{cons}$; Phase 4 achieves block finalization and reveals $K_{evid}$ to ensure non-repudiation.
• Figure 3: Performance comparison of secret key rates. The TF-QKD protocol (red solid line) overcomes the PLOB bound (black solid line) and the distance limitations of MDI-QKD (green dash-dotted line). While BB84 (blue dashed line) shows higher rates at short distances, it lacks the measurement-device-independent security feature inherent to the TF-QKD architecture.
• Figure 4: Supply-demand equilibrium analysis under different network scales ($N$) and transaction throughputs (TPS). The red solid curve represents the TF-QKD key rate using SNSPD parameters, while the dashed lines represent the key consumption. The intersection points ($R_{\max}$) mark the maximum feasible network radius for each scenario.
• Figure 5: Feasibility heatmap of the TF-QKD architecture showing throughput ($\log_{10}$ TPS) as a function of network radius $R$ and node size $N$. The solid white contour represents the high-performance threshold of $10^3$ TPS, while the dashed contour marks $10^2$ TPS. The region to the right indicates the infeasible zone where secure key generation is physically impossible. Specific operational points discussed in the text are marked: the marker at $(R=120, N=50)$ illustrates the limit for metropolitan consortiums, while the marker at $(R=180, N=10)$ demonstrates feasibility for extended regional links.