Exploring Quantum Key Distribution Routing Algorithms

Quantum Key Distribution allows the exchange of symmetric keys with information-theoretic security between adjacent nodes. Key relay techniques in Quantum Key Distribution Networks (QKDNs) address the need for symmetric keys between nodes that are either too distant for establishing a quantum link or separated by intermediate nodes. The Secure Key Rate is limited, which triggers a need to use buffers (Quantum Key Pools) to store keys for later use. The secure key relay uses One-Time Pad, thus the number of links in the route impacts the number of keys used to deliver a pair of symmetric keys. The need for efficient routing algorithms in QKDNs has led to different routing algorithms. This work revisits some routing approaches that have been improved here. Results show that using asymmetrical link costs reduces blocking, a Long Short-Term Memory approach is enhanced by including cross-validation, and finally some strategies to reduce management traffic are proposed.