In order to effectively utilize the costly quantum resource in the practical quantum-secured networking, we proposed lifetime-aware quantum key relay algorithm. The proposed algorithm calculates an end-to-end quantum key relay path, based on the combination of the lifetime and the number of quantum keys of links. In the practical condition, the proposed algorithm reduces 21% of blocking count of quantum-secured service, from that of the conventional key relay algorithm.
In order to effectively utilize the costly quantum resource in the practical quantum-secured networking, we proposed lifetime-aware quantum key relay algorithm. The proposed algorithm calculates an end-to-end quantum key relay path, based on the combination of the lifetime and the number of quantum keys of links. In the practical condition, the proposed algorithm reduces 21% of blocking count of quantum-secured service, from that of the conventional key relay algorithm.
ABSTRACT Quantum key relay over trusted relay nodes is a practical approach to overcoming the distance limitation of quantum key distribution (QKD) protocols in quantum-secured networking. However, the processing delay incurred by the quantum key relay function increases the quantum key response delay (KRD) which serves as a representative quality-of-service (QoS) metric for quantum-secured services. This QoS degradation becomes more pronounced in large-scale quantum-secured networks. To address this issue, we investigate a proactive quantum key relay algorithm that relays and prepares quantum keys for pairs of QKD nodes prior to requests for quantum-secured services. By jointly considering the length of the relay path, the available quantity of quantum keys, and the remaining lifetimes of the quantum keys, the proposed algorithm selects a pair of QKD nodes and performs proactive quantum key relay to establish a quantum key for the selected pair. The proposed algorithm enables more flexible operation by sequentially dividing the proactive quantum key relay algorithm into two parts: one for a relatively short distance pair of QKD nodes and the other for a long-distance pair of QKD nodes. The simulation results demonstrate that, compared with the on-demand quantum key relay algorithm, the proposed algorithm achieves a relative reduction of up to 89.7% in the modeled KRD, accompanied by a corresponding relative decrease of 13.9% in the provisioning ratio of quantum-secured service. Overall, these findings confirm the effectiveness of the proposed proactive quantum key relay algorithm in achieving short-latency quantum-secured networking.
By overcoming the distance limit in quantum key distribution (QKD) technology, key relaying over trusted nodes is regarded as an essential function for practical quantum-secured networking. The key relay function consumes a series of costly quantum key resources to establish an end-to-end key in QKD networks (QKDNs); thus, an efficient key relay algorithm is required. To investigate this problem, we developed an integer linear programming (ILP) formulation that maximizes a balanced summation between max-min fairness and efficiency in the key relay. Inspired by the ILP model, this study developed a key-count differential-based proactive key relay (DPKR) heuristic algorithm to provide a scalable solution for key relays in QKDNs. The proposed DPKR algorithm iteratively selects a set of nodes by considering the key-count differential between nodes and establishes an end-to-end key by relaying it over the selected nodes. Owing to the proactive key relay model, an effective key relay route in the key management layer in the QKDN can be calculated solely by the key-count status in the key management layer. The proposed DPKR algorithm reduces manifold order-of-magnitude in the algorithm computation time at the cost of an acceptable loss in the average and minimum numbers of keys from those of the ILP optimization model. The computation time evaluation clearly manifests a scalability of the DPKR algorithm in quantum-secured networking.
Quantum key distribution (QKD) is an encrypted communication technique based on the principles of quantum mechanics that ensures communication security by exploiting the properties of quantum states. Currently, the transmission efficiency of the QKD system is low. Trusted relay technology is used to solve this problem and achieve long-distance transmission. However, trusted relaying alone cannot decrypt the issues of poor link stability and the low utilization of key resources. To further optimize the system performance, we propose a dynamic routing algorithm. One of the improvement schemes includes the following: firstly, an adjustable-size quantum key pool (QKP) is designed, which can dynamically adjust the size of the refreshing pool according to the actual demand. Secondly, the utilization of key resources is improved by using the residual quantum key model to dynamically obtain the remaining key amount in the QKP and set the key amount threshold. We calculate the link-blocking probability and track the blocking intensity and blocking entry by combining the Poisson process, thus realizing the evaluation of the link stability. Finally, the number of remaining keys in the QKP and the link-blocking probability combine with the random wandering model as the basis of the route selection for the QKD dynamic routing algorithm to achieve efficient key path selection. We validated the algorithm by comparing it with other algorithms on the Mininet simulation platform, and the algorithm proved to have a better performance in terms of congestion avoidance, delay reduction, and improved QKD efficiency. This scheme provides a novel and efficient way to solve the problems in existing QKD systems. It effectively improves the transmission efficiency and strengthens the system’s security by dynamically obtaining the critical volume, accurately evaluating the link state, and selecting the optimal critical path.
Quantum key distribution (QKD) provides information-theoretic security based on quantum mechanics, and as quantum key distribution becomes increasingly practical, questions of how to employ it effectively over largescale networks and large distances becomes increasingly important. In this work, we investigate the B92 entanglement based QKD protocol and a five-layer QKD network architecture consisting of trusted relay nodes. Previous research seldom focused on the ground routing mechanism of QKD networks in detail. Since no intersecting links are beneficial to reducing the key consumption rate and improving link security, combined with the core idea of reducing the number of link relay hops, we propose a minimum path cost multi-path routing algorithm for no intersecting links in quantum key distribution networks. By analyzing the security of the link, we effectively reduce the number of relay nodes and the number of relay links that pass through and give priority to the routing scheme with the minimum number of hops in the number of relay hops, which avoids the congestion and waste caused by the existence of interleaved multi-path in traditional multi-path routing. Meanwhile, the scheme effectively improves the quality of service index, avoids the generation and consumption of redundant keys, and reduces the waste of quantum key resources.
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.
Quantum-secured networking constitutes a layering architecture comprising a user network and a quantum key distribution network (QKDN). In the wavelength division multiplexing-based quantum-secured optical networking, wavelength and quantum key are scarce resources in the user network and QKDN, respectively; hence, an efficient resource dimensioning algorithm is required for practical quantum-secured services. Therefore, we investigated a resource dimensioning problem for the standardization-compatible quantum-secured networking model, where a data routing path in the user network and a quantum key relay path in the QKDN are interdependent. As benchmarking solutions, we first developed integer linear programming (ILP) formulations for wavelength and quantum key resource optimal quantum-secured networking. To obtain the tractable solution, an iterative heuristic algorithm was proposed, in which a path of a quantum-secured service was calculated by considering the statuses of both wavelength and quantum key resources. Simulation study on practical backbone topologies revealed that the proposed heuristic algorithm reduced manifold order-of-magnitude in the algorithm computation time at the costs of acceptable overheads in the wavelength and quantum key resources, from those of the ILP optimizations.