The key flooding protocol in Quantum Key Distribution Networks (QKDNs) is a fully decentralized strategy that proactively distributes key material to pre-establish end-to-end key pools, enabling immediate delivery to clients. We enhance this protocol to increase key availability and overall distribution efficiency. The protocol has been implemented in an in-house developed, fully functional Key Management System (KMS), and the evaluation has been carried out over a Docker-based simulated network with a representative topology, demonstrating practicality and feasibility in realistic deployment scenarios. Experimental results show that, under moderate network load, the enhanced protocol significantly improves key request success rates by up to 5.6 % while authentication overhead is reduced by up to 59 % compared to the baseline flooding approach. The protocol maintains stable performance under stress conditions, preserving robustness against increased traffic.
The key flooding protocol in Quantum Key Distribution Networks (QKDNs) is a fully decentralized strategy that proactively distributes key material to pre-establish end-to-end key pools, enabling immediate delivery to clients. We enhance this protocol to increase key availability and overall distribution efficiency. The protocol has been implemented in an in-house developed, fully functional Key Management System (KMS), and the evaluation has been carried out over a Docker-based simulated network with a representative topology, demonstrating practicality and feasibility in realistic deployment scenarios. Experimental results show that, under moderate network load, the enhanced protocol significantly improves key request success rates by up to 5.6 % while authentication overhead is reduced by up to 59 % compared to the baseline flooding approach. The protocol maintains stable performance under stress conditions, preserving robustness against increased traffic.
Quantum key distribution (QKD) allows the distribution of secret keys for quantum-secure communication between two distant parties, vital in the quantum computing era in order to protect against quantum-enabled attackers. However, overcoming rate-distance limits in QKD and the establishment of quantum key distribution networks necessitate key relaying over trusted nodes. This process may be resource-intensive, consuming a substantial share of the scarce QKD key material to establish end-to-end secret keys. Hence, an efficient scheme for key relaying and the establishment of end-to-end key pools is essential for practical and extended quantum-secured networking. In this paper, we propose and compare two protocols for managing, storing, and distributing secret key material in QKD networks, addressing challenges such as the success rate of key requests, key consumption, and overhead resulting from relaying. We present an innovative, fully decentralized key distribution strategy as an alternative to the traditional hop-by-hop relaying via trusted nodes, where three experiments are considered to evaluate performance metrics under varying key demand. Our results show that the decentralized pre-flooding approach achieves higher success rates as application demands increase. This analysis highlights the strengths of each approach in enhancing QKD network performance, offering valuable insights for developing robust key distribution strategies in different scenarios.
Key Management Systems (KMSs) are essential for secure and scalable Quantum Key Distribution (QKD) networks. For successful integration of QKD into existing security protocols, it is crucial that KMSs can reliably deliver keys with sufficiently low latency. Yet, the performance of practical implementations remains insufficiently characterized. We benchmarked the throughput and latency of the key-delivery interfaces of several commercial KMS solutions alongside an in-house developed system. Our evaluation reveals that the KMS performance degrades significantly under high-workload conditions, indicating that current designs require substantial optimization before they can support large-scale, high-demand QKD deployments.
Quantum key distribution (QKD) is experiencing a rapid increase of interest due to its security advantages in the face of quantum computers. However, typical QKD deployments are point-to-point and limited in terms of distance, which significantly restricts their utilization for end-user applications. To overcome these restrictions, trusted relays are adopted as intermediate nodes to allow the transition to QKD networks (QKDNs), where one of the hallmarks is the key management system. In this work, we investigate different key allocation strategies as a method to enhance the performance of key management systems in QKDN from the perspective of key allocation success rate and key delivery delay. We first describe an upgrade model from classical to QKDN at three distinct network layers—quantum, key management, and service. Then, we propose a novel, to our knowledge, key allocation strategy leveraging the benefits of key storage and relaying as a solution to improve the QKDN performance. To achieve this, our method makes use of end-to-end virtual quantum key pools (VQKPs) implemented between non-adjacent nodes requesting key material. We introduce static and dynamic upper and lower threshold limits at the VQKP level, with the dynamic thresholds adapted according to application demand, to control the key distribution in the network and fill the pools ahead of end-user requests. We demonstrate through simulations that the introduction of thresholds achieves performance enhancement and explain the trade-off between the key allocation success rate and key delivery delay evaluation metrics in comparison with different on-demand key allocation strategies.
In recent years, multi-hop Quantum Key Distribution (QKD) network has been proven as a promising solution through rigorous practices to provide end-to-end key exchange service for arbitrary communication parties. However, existing decentralized solutions still face critical challenges including consistency and fairness that stem from storable nature of quantum key material. Thus, in this paper, we first devise a Key Management and Service (KM&S) framework for decentralized multi-hop QKD networks, which provides functional decoupling and pipeline processing to guarantee flexibility and compatibility for practical implementation. After that, to address consistency and fairness challenges during end-to-end key exchange service, we focus on two aspects including local key management and end-to-end congestion control, and respectively propose an elastic key supply rate control scheme named AUTO and a Capacity Probing-driven Backpressure Flow Control (CP-BFC) scheme. Furthermore, we construct an experiment platform equipped with realistic QKD devices based on China metropolitan QKD network topology to implement the proposed framework and schemes, and conduct extensive experiments compared to representative schemes in existing studies. The experimental results show that AUTO&CP-BFC significantly outperforms representative schemes in terms of consistency and fairness.
Quantum key distribution (QKD) is a symmetric key exchange mechanism designed to enhance the security of current communication systems. Although QKD provides unconditional security, it also comes with deployment challenges. One challenge is the distance limitation between the transmitter and receiver, which restricts the large-scale adoption of QKD. To overcome this, trusted relays are used as intermediate nodes, allowing QKD to evolve from distance-limited point-to-point connections to unlimited QKD networks (QKDN). With an increasing deployment of QKD and a growing number of applications requesting keys, quality of service (QoS) constraints must be set for efficient key resource management to alleviate the risk of rejecting application requests. In this work, we integrate key delivery delay and maximum requested key size as QoS constraints in a novel key allocation algorithm built on three QKDN layers – quantum, key management and service. Moreover, we design key relaying using quantum key pools and virtual quantum key pools as storage mechanisms. We use static and dynamic weights for relay path computation and evaluate their impact on the proposed key allocation strategies with QoS constraints and find that static weights show a good overall performance for QKDN, while performance with dynamic weights varies based on historical key consumption data.
Key management strategies are a critical yet often overlooked aspect of integrating quantum key distribution (QKD) networks as a service into critical infrastructure. It has a considerable impact on the efficiency of QKD network services, thereby shaping its suitability for diverse applications. In this paper, we examine the effectiveness of key management strategies developed through practical testbeds, identifying their strengths and weaknesses. A novel, to the best of our knowledge, organization of key storage to enhance key construction efficiency and overall service performance is introduced. Using simulation tools, the proposed strategy is evaluated against existing approaches, demonstrating superior performance and effectiveness.