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) 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.
In the initial stage of the quantum Internet, most of the practical quantum networks have been deployed relying on diverse individual quantum key distribution (QKD) protocols. However, this single-protocol paradigm cannot fulfill the heterogeneous requirements of the users, hence market-penetration of quantum networks is limited. Given the recent advances in QKD protocols, the next generation quantum networks are expected to support both legacy and emerging QKD protocols. However, the evolution from single-protocol to multi-protocol quantum networks poses numerous challenging problems. As a remedy, we conceive a practical protocol translation framework for supporting this migration from single-protocol to large-scale multi-protocol quantum networks. Furthermore, we propose a programmable multi-functional relay node architecture for harmonizing the components of a suitable relay node. A pair of protocol translation policies are presented for meeting the challenging security requirements of migration requests, which are compared to the single-protocol-based migration solutions both in terms of the translation success probability attained (i.e., the proportion of migration requests with successful protocol translation), and the average relaying risk probability encountered (i.e., the mean of the relaying risk probabilities of end-to-end key negotiation in a quantum network). Finally, we highlight a suite of open problems in both quantum secure direct communication and quantum teleportation for research into future multi-protocol quantum networks.
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), 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.
Abstract As the first stage of the quantum Internet, quantum key distribution (QKD) networks hold the promise of providing long-term security for diverse users. Most existing QKD networks have been constructed based on independent QKD protocols, and they commonly rely on the deployment of single-protocol trusted relay chains for long reach. Driven by the evolution of QKD protocols, large-scale QKD networking is expected to migrate from a single-protocol to a multi-protocol paradigm, during which some useful evolutionary elements for the later stages of the quantum Internet may be incorporated. In this work, we delve into a pivotal technique for large-scale QKD networking, namely, multi-protocol relay chaining. A multi-protocol relay chain is established by connecting a set of trusted/untrusted relays relying on multiple QKD protocols between a pair of QKD nodes. The structures of diverse multi-protocol relay chains are described, based on which the associated model is formulated and the policies are defined for the deployment of multi-protocol relay chains. Furthermore, we propose three multi-protocol relay chaining heuristics. Numerical simulations indicate that the designed heuristics can effectively reduce the number of trusted relays deployed and enhance the average security level versus the commonly used single-protocol trusted relay chaining methods on backbone network topologies.
Quantum key distribution (QKD) networks are potential to be widely deployed in the immediate future to provide long-term security for data communications. Given the high price and complexity, multi-tenancy has become a cost-effective pattern for QKD network operations. In this work, we concentrate on addressing the online multi-tenant provisioning (On-MTP) problem for QKD networks, where multiple tenant requests (TRs) arrive dynamically. On-MTP involves scheduling multiple TRs and assigning non-reusable secret keys derived from a QKD network to multiple TRs, where each TR can be regarded as a high-security-demand organization with the dedicated secret-key demand. The quantum key pools (QKPs) are constructed over QKD network infrastructure to improve management efficiency for secret keys. We model the secret-key resources for QKPs and the secret-key demands of TRs using distinct images. To realize efficient On-MTP, we perform a comparative study of heuristics and reinforcement learning (RL) based On-MTP solutions, where three heuristics (i.e., random, fit, and best-fit based On-MTP algorithms) are presented and a RL framework is introduced to realize automatic training of an On-MTP algorithm. The comparative results indicate that with sufficient training iterations the RL-based On-MTP algorithm significantly outperforms the presented heuristics in terms of tenant-request blocking probability and secret-key resource utilization.
Current and next-generation networks are threatened by emerging attacks from quantum computers. To protect these services against quantum threat, quantum key distribution (QKD) using optical networks is being investigated and tested as a safe countermeasure to provide information-theoretic security. Although recent studies confirm the feasibility of QKD over optical networks, two main technical challenges, among others, remain unaddressed: the limited rate of generating keys requires efficient key distribution to secure the numerous applications, and as key requests from applications can be characterized by different importance, QKD networks need a key distribution platform that accounts for such diversity. To address these challenges, we propose to incorporate the paradigm of Information-Centric Networking (ICN) within the QKD process, and we describe a novel information-centric quantum key distribution (IC-QKD) network for efficient and differentiated key distribution. We first design a semantic-based key distribution scheme, which leverages ICN to incorporate the knowledge of application importance in QKD and to enhance the resource efficiency of QKD by decoupling the sender from its receiver. We then propose an in-network key-caching scheme, which is especially advantageous for multi-cast applications, as keys can be cached and reused for multiple users of a multicast group to accelerate key distribution. Finally, we design a semantic-based application analysis for semantic-based key caching and distribution, which serves various applications with different priorities. Simulation results show that the proposed QKD network can reach up to about 16 percent increase in the capability of serving key requests with respect to the existing QKD network.