Exploring Key Pre-provisioning in Quantum Key Distribution Networks

Quantum Key Distribution (QKD) networks are proposed as a solution to ensure information-theoretic security for symmetric key exchange in post-quantum networks. Key generation is limited and variable, hence Quantum Key Pools (QKPs) have been proposed to allow applications a quicker access to quantum keys for secure data exchange. Nevertheless, On-Demand (OD) key relaying can still entail a delay too large for some applications. Therefore, the concept of key provisioning has been proposed to expedite key supply whenever necessary, resulting in Virtual QKPs for non-adjacent QKD nodes. After the implementation of a key pre-provisioning strategy inspired by an approach proposed by other authors, some novel variants are proposed that aim to decrease demand blocking due to the lack of keys, without significantly increasing the delay for key supply. In this work, an experimental study is conducted, where different settings are considered for the simulation parameters (including the QKP capacity). We conclude that the different pre-provisioning strategies allow for a reduction in the blocking probability (calculated for demands and for data) and in the delay, when compared to an OD strategy.