Overview of Routing Approaches in Quantum Key Distribution Networks

TL;DR

This survey reviews 26 routing strategies for quantum key distribution networks, highlighting their performance, challenges, and future research directions to enable secure, scalable quantum communication infrastructure.

Contribution

It provides a comprehensive classification and analysis of QKD routing approaches, identifying key trade-offs and emerging frameworks for secure quantum networks.

Findings

Dynamic, key-aware routing reduces rejection rates by 25-40%.

Multi-path strategies increase resilience but raise key consumption by 30-60%.

SDN frameworks enable flexible, QoS-aware routing in hybrid networks.

Abstract

Quantum Key Distribution (QKD) networks enable unconditionally secure key exchange using quantum mechanical principles. However, routing cryptographic keys across multi-hop quantum networks introduces challenges unique to quantum communication. This survey analyzes and classifies 26 routing strategies proposed between 2013 and 2024 for terrestrial, satellite, and hybrid QKD infrastructures. Dynamic, key-aware routing algorithms have been shown to reduce service rejection rates by 25-40% compared to static shortest-path methods by incorporating real-time key pool availability and link error rates. Multi-path strategies improve resilience against trusted-node compromise by distributing keys across disjoint routes, albeit with an increase in key consumption of 30-60%. SDN-based orchestration frameworks emerge as essential enablers of flexible, QoS-aware routing for hybrid networks integrating terrestrial fibers and intermittent satellite links. Critical research directions include reducing dependence on trusted nodes through quantum repeaters or post-quantum cryptography, developing standardized key management interfaces for interoperability, and adopting AI-driven predictive routing for adapting to fluctuating network states. This comprehensive synthesis of routing algorithms, performance trade-offs, and unresolved issues offers practical guidance for engineering secure, adaptable, and large-scale QKD networks capable of meeting real-world deployment demands.