Abstract Quantum key distribution (QKD) is gradually evolving from dedicated-link deployment toward networked integration with existing optical network infrastructures. In quantum–classical co-propagation scenarios, the quality of quantum links is readily affected by noise interference and device non-idealities, making efficient routing and resource allocation in multi-node networks a critical issue. To address this problem, this paper proposes a security-aware, data-driven QKD routing and admission control framework for software-defined networking (SDN)-controlled quantum–classical integrated optical networks. In the proposed framework, a variational quantum classifier (VQC) is employed as a link-state pre-screening mechanism, and the detection results are further used to support candidate path screening, routing decision-making, and resource allocation. In addition, the actual key generation capability of each path is further validated by incorporating the QKD protocol procedure into the decision process. Simulation results show that, compared with conventional baseline methods, the proposed method achieves stable performance under varying traffic loads, non-ideal conditions, and larger network scales, while yielding moderate improvements in system blocking ratio, average quantum signal-to-noise ratio (QSNR), and final key length.
Abstract Quantum key distribution (QKD) is gradually evolving from dedicated-link deployment toward networked integration with existing optical network infrastructures. In quantum–classical co-propagation scenarios, the quality of quantum links is readily affected by noise interference and device non-idealities, making efficient routing and resource allocation in multi-node networks a critical issue. To address this problem, this paper proposes a security-aware, data-driven QKD routing and admission control framework for software-defined networking (SDN)-controlled quantum–classical integrated optical networks. In the proposed framework, a variational quantum classifier (VQC) is employed as a link-state pre-screening mechanism, and the detection results are further used to support candidate path screening, routing decision-making, and resource allocation. In addition, the actual key generation capability of each path is further validated by incorporating the QKD protocol procedure into the decision process. Simulation results show that, compared with conventional baseline methods, the proposed method achieves stable performance under varying traffic loads, non-ideal conditions, and larger network scales, while yielding moderate improvements in system blocking ratio, average quantum signal-to-noise ratio (QSNR), and final key length.
Quantum key distribution (QKD) has been identified as a secure method for providing symmetric keys between two parties based on the fundamental laws of quantum physics, making it impossible for a third party to copy the quantum states exchanged without being detected by the sender (Alice) and receiver (Bob) and without altering the original states. However, when QKD is applied in a deployed optical network, physical-layer intrusions may occur in the optical links by injecting harmful signals directly into the optical fiber. This can have a detrimental effect on the key distribution and eventually lead to its disruption. On the other hand, network architectures with software-defined networking (SDN) benefit from a homogeneous and unified control plane that can seamlessly control a QKD-enabled optical network end-to-end. There is no need for a separate QKD control, a separate control for each segment of an optical network, and an orchestrator to coordinate between these parts. Furthermore, SDN allows customized and application-tailored control and algorithm provisioning, such as QKD-aware optical path computation, to be deployed in the network, independent of the underlying infrastructure. Therefore, in this paper, we investigate the integration of the application, SDN, and QKD infrastructure layers and confirm capability for flexible supervision and uninterrupted key service provisioning in the event of link level attacks. An experimental demonstrator is used, for the first time, to verify the architecture proposed, considering real-time monitoring of quantum parameters and fiber-optic link intruders to emulate real-world conditions. Furthermore, attacks on a standard single-mode fiber (via a 3 dB coupler) and a multicore fiber (via an adjacent core) are undertaken to explore different connectivity between QKD units. Results show additional attacker identification and switching time of less than 60 ms for the link cases investigated, being negligible compared to the total (re-)initialization time of 14 min of the QKD units.
The demand for secure communication in the age of quantum technologies has driven progress in quantum key distribution (QKD) techniques for optical networks. This research addresses the issues of high blocking probabilities (BPs) and the proper utilization of quantum resources in varying network loads by introducing a novel heuristic approach, termed dynamic security-aware quantum resource allocation (D-SQRA), designed for dynamic resource allocation in QKD-enabled optical networks. We propose two D-SQRA algorithms to employ an adaptive resource assignment (RA) strategy that concurrently addresses routing, wavelength, and time-slot selection while dynamically modifying security levels according to the real-time network load and resource availability. We evaluate the proposed D-SQRA performance against two conventional methods, namely, fixed security quantum resource allocation (F-SQRA) and baseline quantum resource allocation (B-QRA). We discuss the results for NSFNET and UBN24 topologies for network security performance metrics such as network security performance (NSP), BP, quantum key utilization (QKU), and time-slot utilization. The results show that the proposed D-SQRA algorithms provide significant improvement with respect to conventional techniques in addressing proper resource utilization and management by reducing BPs of the new incoming connection requests.
As a prototype of quantum communications, quantum key distribution (QKD) is recommended for integration into the existing optical infrastructures to enable scalable quantum networking. This necessitates the development of supporting resource allocation strategies for carrier-grade operations. In this work, we propose a quantum-aware RWA framework with dual-granularity power control (QRA-PC) to mitigate quantum-classical interference under hybrid network constraints. In a 9-node mesh network with 1 GHz discrete-variable QKD systems coexisting in the C-band, QRA-PC with local power control mode achieves an average SKR of 891.9 kb/s at a traffic load of 50 erlangs, compared to the first-fit baseline of 50.4 kb/s. This result is achieved without incurring any classical traffic blocking.
Quantum Key Distribution (QKD) networks enable unconditionally secure key exchange using quantum mechanical principles. However, routing cryptographic keys across multi-hop quantum networks introduces challenges unique to quantum communication. This survey analyzes and classifies 26 routing strategies proposed between 2013 and 2024 for terrestrial, satellite, and hybrid QKD infrastructures. Dynamic, key-aware routing algorithms have been shown to reduce service rejection rates by 25-40% compared to static shortest-path methods by incorporating real-time key pool availability and link error rates. Multi-path strategies improve resilience against trusted-node compromise by distributing keys across disjoint routes, albeit with an increase in key consumption of 30-60%. SDN-based orchestration frameworks emerge as essential enablers of flexible, QoS-aware routing for hybrid networks integrating terrestrial fibers and intermittent satellite links. Critical research directions include reducing dependence on trusted nodes through quantum repeaters or post-quantum cryptography, developing standardized key management interfaces for interoperability, and adopting AI-driven predictive routing for adapting to fluctuating network states. This comprehensive synthesis of routing algorithms, performance trade-offs, and unresolved issues offers practical guidance for engineering secure, adaptable, and large-scale QKD networks capable of meeting real-world deployment demands.
Quantum cryptography is one of the emerging nascent fields in the area of quantum computing. It has found its places in various diversified applications across the domains. Ensuring long term information security in the post-quantum era requires the redesigning of conventional algorithms, which are quantum resistant. In the post quantum era, the field of quantum cryptography promises trusted communications, but practical implementation of the networks suffers serious challenges from adaptive conditions like noise and failures of the network links. Revaluation of new quantum resistant security algorithms need to be considered. This paper presents a hybrid system that combines Machine Learning (ML), Quantum Key Distribution (QKD) along with software-defined networking (SDN) for real-time allocation of resources in quantum networks. This approach uses the random forest classifier to predict a different robust network path based on the key rate and quantum bit error rate parameters. As network conditions change, the SDN controller makes it possible to choose a dynamic link. The simulations methods show that the system can adapt to increased noise and compromised links and attain key rates of up to 12.5 Mbps with a QBER rate as low as 0.01. In comparison to manual resource allocation in quantum networks, simulation findings demonstrate greater adaptability and security. Software-defined networking (SDN), quantum bit error rate (QBER), quantum key distribution (QKD), post-quantum cryptography (PQC), machine learning, and resource allocation are the index terms. Results show higher adaptability and security with respect to manual allocation of resources in quantum networks.
Software-defined networking (SDN) has emerged as a promising paradigm for managing and controlling network resources efficiently. However, ensuring the security of data packets transmitted within an SDN environment remains a critical challenge. Traditional networking relies on static configurations, while SDN offers dynamic control and programmability, revolutionizing network management. In SDN, the application layer employs tools like OpenDaylight and Mininet for network management and testing. The control layer, managed by controllers such as Floodlight or ONOS, orchestrates traffic flow among switches. In the infrastructure layer, Quantum Key Distribution (QKD) with the BB84 protocol ensures secure communication. Together, these layers enable agile, programmable, and secure networking paradigms. This paper proposes integrating quantum key distribution (QKD) into SDN architectures to bolster packet-level security. By leveraging quantum entanglement and uncertainty, a secure communication channel between SDN controllers and switches is established, resilient to quantum attacks. Evaluation through simulations and real-world experiments demonstrates efficacy in mitigating security threats while minimizing overhead and latency, advancing SDN security IEEE 802.1X capabilities and leveraging quantum technologies for cybersecurity.