Quantum key distribution (QKD), as one of the pivotal technologies for future-proof security, is progressing toward large-scale networking. Since different QKD protocols have their own potential advantages and shortcomings, the interconnection of metropolitan quantum networks based on heterogeneous protocols is an important step to realize a wide-area quantum network. In this scenario, the provision of inter-domain key services still faces challenges in terms of success probability, security level, and the balance between key supply and demand. Targeting these challenges, this work proposes four secret key rate (SKR) adaptive inter-domain key service provisioning policies based on the dynamic node bypass and elastic SKR slicing, namely, IrB-IaB (inter-domain bypass and intra-domain bypass), IrS-IaS (inter-domain slicing and intra-domain slicing), IrB-IaS (inter-domain bypass and intra-domain slicing), and IrS-IaB (inter-domain slicing and intra-domain bypass). The proposed policies are applicable to multi-domain quantum networks with heterogeneous protocols such as GG02-based metropolitan and BB84-based inter-domain connections, as well as BB84-based metropolitan and TF-based inter-domain connections. Furthermore, the inter-domain key service provisioning model is formulated, and four corresponding SKR-adaptive inter-domain key service provisioning algorithms are designed. Simulation results show that the IrS-IaS algorithm performs better in terms of success probability as well as the equilibrium degree between key supply and demand. The security level is quantitatively evaluated through the number of trusted relays. The IrB-IaB algorithm achieves the lowest number of trusted relays, which is more than 20% lower than the benchmark algorithm, resulting in a higher security level and lower cost. The key resource utilization efficiency is assessed via the equilibrium degree. Both the IrB-IaS and IrS-IaB algorithms have the potential to balance the effectiveness and reliability of quantum networks. In particular, the IrS-IaB algorithm is beneficial in achieving the best trade-off between key resource utilization efficiency and security level.
Quantum key distribution (QKD), as one of the pivotal technologies for future-proof security, is progressing toward large-scale networking. Since different QKD protocols have their own potential advantages and shortcomings, the interconnection of metropolitan quantum networks based on heterogeneous protocols is an important step to realize a wide-area quantum network. In this scenario, the provision of inter-domain key services still faces challenges in terms of success probability, security level, and the balance between key supply and demand. Targeting these challenges, this work proposes four secret key rate (SKR) adaptive inter-domain key service provisioning policies based on the dynamic node bypass and elastic SKR slicing, namely, IrB-IaB (inter-domain bypass and intra-domain bypass), IrS-IaS (inter-domain slicing and intra-domain slicing), IrB-IaS (inter-domain bypass and intra-domain slicing), and IrS-IaB (inter-domain slicing and intra-domain bypass). The proposed policies are applicable to multi-domain quantum networks with heterogeneous protocols such as GG02-based metropolitan and BB84-based inter-domain connections, as well as BB84-based metropolitan and TF-based inter-domain connections. Furthermore, the inter-domain key service provisioning model is formulated, and four corresponding SKR-adaptive inter-domain key service provisioning algorithms are designed. Simulation results show that the IrS-IaS algorithm performs better in terms of success probability as well as the equilibrium degree between key supply and demand. The security level is quantitatively evaluated through the number of trusted relays. The IrB-IaB algorithm achieves the lowest number of trusted relays, which is more than 20% lower than the benchmark algorithm, resulting in a higher security level and lower cost. The key resource utilization efficiency is assessed via the equilibrium degree. Both the IrB-IaS and IrS-IaB algorithms have the potential to balance the effectiveness and reliability of quantum networks. In particular, the IrS-IaB algorithm is beneficial in achieving the best trade-off between key resource utilization efficiency and security level.
Most of the existing metropolitan quantum networks are implemented based on a single quantum key distribution protocol, and interconnecting metropolitan quantum networks implemented by different protocols are the development trend of large-scale quantum networks, but there are still some problems in the provision of inter-domain key services, such as low possibility of success and mismatch between key supply and demand. To solve the above problems, this paper proposes two on-demand inter-domain key service provisioning strategies for multi-domain cross-protocol quantum networks, namely, on-demand provisioning strategy based on BB84 bypass first (BB84-BF) and on-demand provisioning strategy based on MDI bypass first (MDI-BF). Meanwhile, a service provisioning model for multi-domain cross-protocol quantum networks is constructed, and an on-demand inter-domain key service provisioning algorithm is designed. Moreover, numerical simulations and performance evaluation are carried out under two scenarios: high key rate demand and low key rate demand for two-domain and three-domain quantum network topologies. Simulation results verify that the proposed on-demand provisioning strategies have better applicability to different multi-domain quantum networks. In addition, for different key rate requirements, the MDI-BF strategy and BB84-BF strategys have different performance advantages under different performance indicators. For example, in terms of the success possibility of inter-domain key service requests, the MDI-BF strategy is more suitable for the low key rate requirements (~30% higher than the traditional strategies in two domain topologies), while the BB84-BF strategy is more suitable for the high key rate requirements (~19% higher than the traditional strategies under two domain topologies). In addition, compared with the traditional strategies, the proposed on-demand provisioning strategies can increase the balance degree between key supply and demand by more than one order of magnitude. Hence, the proposed strategies can reduce the cost of inter-domain key service provisioning and improve the realistic security level.
Abstract As the cornerstone of future information security, quantum key distribution (QKD) is evolving towards large-scale hybrid discrete-variable/continuous-variable (DV/CV) multi-domain quantum networks. Meanwhile, multicast-oriented multi-party key negotiation is attracting increasing attention in quantum networks. However, the efficient key provision for multicast services over hybrid DV/CV multi-domain quantum networks remains challenging, due to the limited probability of service success and the inefficient utilization of key resources. Targeting these challenges, this study proposes two key-resource-aware multicast-oriented key provision strategies, namely the link distance-resource balanced key provision strategy and the maximum shared link key provision strategy. The proposed strategies are applicable to hybrid DV/CV multi-domain quantum networks, which are typically implemented by GG02-based intra-domain connections and BB84-based inter-domain connections. Furthermore, the multicast-oriented key provision model is formulated, based on which two heuristic algorithms are designed, i.e., the shared link distance-resource (SLDR) dependent and the maximum shared link distance-resource (MSLDR) dependent multicast-oriented key provision algorithms. Simulation results verify the applicability of the designed algorithms across different multi-domain quantum networks, and demonstrate their superiority over the benchmark algorithms in terms of the success probability of multicast service requests, the number of shared links, and the key resource utilization.
QKD technology is being increasingly adopted inside the network core for protecting information transport against any form of computational attacks. However, the use of QKD for wide-area internetworking is still challenging and costly, due to its strong trust assumptions and the low achievable key rates in long QKD links. This paper presents a standards-driven design and implementation of a unified hybrid key delivery service for a network of isolated QKD domains (subnetworks using QKD as provider technology for secret key generation) connected via classical WAN links. The framework follows a distributed architecture and uses a hybrid approach where keys generated in a domain are securely relayed to other domains with PQC (Kyber), dynamically routed, and managed at the system level. The solution has been implemented in an operational testbed comprising three regional subnetworks. We present the design principles, the deployment, and the experimental performance results for this scalable key delivery service.
Quantum key distribution (QKD) is a promising technology that can provide future-proof security. With the emergence of multiple advanced QKD protocols, the QKD protocol upgrading for a metropolitan quantum optical network (MQON) is critical for fulfilling the requirements of users for secret keys with a high security level. Conventionally, due to the lack of effective QKD protocol upgrading strategies for MQONs, massive amounts of resources have to be consumed during QKD protocol upgrading, resulting in high costs. In order to reduce the costs for practical implementation of QKD protocol upgrading, in this work, a new policy of QKD protocol upgrading is proposed, where the bypass technique is adopted to decouple multiple protocols from the linking patterns for efficient resource utilization. Moreover, we illustrate a multi-role QKD node structure for enabling the harmonious operation of multiple QKD protocols. A mixed integer linear programming (MILP) model and a novel divided-packet-based QKD protocol upgrading algorithm are designed to save costs by relying on flexible traffic management. We also propose a fixed-chain-based QKD protocol upgrading algorithm with fixed traffic management for achieving low costs. Simulation results indicate that the proposed heuristic algorithms are significantly more cost effective than the associated benchmark algorithms, while the MILP model can reduce the cost of protocol upgrading by 41% compared with the benchmark.
Quantum key distribution (QKD) can provide long-term security for numerous users. Currently, quantum networks are still in the early stages of small-scale deployment, most of which can only support a single QKD protocol (QKDP). However, with the advancement of various QKDPs, a single-protocol quantum network is no longer sufficient to meet the demands of multiple users, prompting the emergence of multi-protocol quantum networks. Nevertheless, the transition from a single-protocol to a multi-protocol quantum network still faces many challenging issues, such as key negotiation interruptions due to device initialization and channel calibration during protocol updating. To address the quantum key negotiation interruption problem, we propose a seamless key negotiation oriented multi-protocol updating algorithm in this work, which can fulfill the protocol updating requests of different users in quantum metropolitan networks. Furthermore, to better improve network performance while meeting diverse user demands, we propose four heuristic algorithms for optimal QKDP recommendation, focusing on their applications for multi-protocol updating in different types of typical networks. We perform the simulations with different QKDP recommendation algorithms to analyze the impact of the cache time of the key cache area on the key negotiation interruption probability and the time resource utilization. Simulation results demonstrate that the proposed algorithm can reduce the key negotiation interruption probability by 77.7% while increasing the time resource utilization by 15.3% compared to no key cache area.
Quantum Key Distribution (QKD) is considered to be the ultimate solution to communication security. However, current QKD devices, especially quantum photon sources, are expensive, and they can generate secret keys only at a low rate. In this paper, we first consider homogeneous trusted-relay-based QKD networks where every request has the same amount of secret key requirement and every photon source has the same key distribution rate, and design an approach named RPSP to not only minimize the number of photon sources needed in a network to ensure at least one feasible relay path exists for any potential QKD requests but also save the time to complete a batch of QKD requests by jointly optimizing the routing of relay paths and the provisioning of photon sources to distribute secret keys. Then, we extend RPSP to RPSP-HN which can be applied to heterogeneous networks where requests have different secret key requirements and photon sources distribute keys at different rates. Furthermore, we also extend RPSP to RPSP-HY, which considers that some of the nodes in a network is untrusted. Compared with existing works, RPSP and its extensions focus on more practical scenarios where only some of the nodes are equipped with photon sources and they leverage optical switching to enable dynamic photon source provisioning such that we can utilize QKD devices more efficiently. Extensive simulations show that compared with baseline schemes, RPSP, RPSP-HN, and RPSP-HY can save up to 33%, 37%, and 25% of the time to complete a batch of QKD requests in homogeneous, heterogeneous, and hybrid QKD networks, respectively.