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Journal of Optical Communications and Networking

Monitoring and Physical-Layer Attack Mitigation in SDN-Controlled Quantum Key Distribution Networks

E. Hugues-Salas, Foteini Ntavou, Dimitris Gkounis, George Theodore Kanellos, Reza Nejabati, Dimitra E. Simeonidou

Published Jan 15, 2019• 49 citations
Publisher

Abstract

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.

DOI
10.1364/jocn.11.00a209

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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 rapid evolution of digital infrastructure has raised significant concerns about the security of data transmission, particularly with the advent of quantum computing. Traditional cryptographic algorithms are vulnerable to attacks, highlighting the need for quantum-resistant solutions. This paper presents the integration of Quantum Key Distribution (QKD) with Software-Defined Networking (SDN) and network slicing to build a secure, programmable, and flexible network architecture. QKD ensures unconditional security based on quantum mechanics by enabling key distribution with the ability to detect eavesdropping through quantum bit error rates (QBER). SDN provides centralized control and real-time traffic management, while network slicing allows isolation, reliability and customization of traffic flows for specific applications such as URLLC, eMBB, and mMTC. When abnormal QBER or decryption failures are detected, mitigation actions such as Quantum key refresh, traffic rerouting, or attacker isolation are triggered and Performance evaluation of the system is based on Latency and throughput Experimental validation using Mininet and Ryu demonstrates secure key distribution, attack detection, and slice-specific threat mitigation. This integrated approach enhances end-to-end security for next-generation networks, with strong applicability to5G/6G\mathbf{5 G} \boldsymbol{/} \mathbf{6 G}5G/6G, IoT, and mission-critical services.
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.
Software Defined Networking is increasingly seen as one of the best choices to create a Quantum Key Distribution (QKD) Network, especially if the aim is also its integration into a standard telecommunications network. The degree of flexibility afforded by this paradigm allows the creation of a network whose control mechanisms can be made aware simultaneously of the capabilities installed at the classical optical transport level as well as those at the quantum level. This is interesting not only to manage the coexistence between a classical and a quantum network sharing the same infrastructure, but also for future applications beyond QKD. This flexibility is due to a formal separation between the control and data forwarding planes. The logically centralized SDN controller gathers all relevant information monitoring the behavior of the hole network. It can act on the programmable quantum or classical devices opening many possibilities to share a common infrastructure, that can reach even the level of a single fiber strand to manage the signals that go through it in a compatible way. The same controller can use this information to manage the fundamental task of a QKD network, namely the key transport. Here we briefly report on the implementation of the SDN-QKD controller used in the Madrid testbed and its use to allow multi-vendor end-to-end key transport between any two nodes in the network.
Quantum key distribution (QKD) is a state-of-the-art method of generating cryptographic keys by exchanging single photons. Measurements on the photons are constrained by the laws of quantum mechanics, and it is from this that the keys derive their security. Current public key encryption relies on mathematical problems that cannot be solved efficiently using present-day technologies; however, it is vulnerable to computational advances. In contrast QKD generates truly random keys secured against computational advances and more general attacks when implemented properly. On the other hand, networks are moving towards a process of softwarization with the main objective to reduce cost in both, the deployment and in the network maintenance. This process replaces traditional network functionalities (or even full network instances) typically performed in network devices to be located as software distributed across commodity data centers. Within this context, network function virtualization (NFV) is a new concept in which operations of current proprietary hardware appliances are decoupled and run as software instances. However, the security of NFV still needs to be addressed prior to deployment in the real world. In particular, virtual network function (VNF) distribution across data centers is a risk for network operators, as an eavesdropper could compromise not just virtualized services, but the whole infrastructure. We demonstrate, for the first time, a secure architectural solution for VNF distribution, combining NFV orchestration and QKD technology by scheduling an optical network using SDN. A time-shared approach is designed and presented as a cost-effective solution for practical deployment, showing the performance of different quantum links in a distributed environment.
Today’s networks are quickly evolving toward more dynamic and flexible infrastructures and architectures. This software-based evolution has seen its peak with the development of the software-defined networking (SDN) and network functions virtualization (NFV) paradigms. These new concepts allow operators to automate the setup of services, thus reducing costs in deploying and operating the required infrastructure. On the other hand, these novel paradigms expose new vulnerabilities, as critical information travels through the infrastructure from central offices, down to remote data centers and network devices. Quantum key distribution (QKD) is a state-of-the-art technology that can be seen as a source of symmetric keys in two separated domains. It is immune to any algorithmic cryptanalysis and is thus suitable for long-term security. This technology is based on the laws of physics, which forbids us from copying the quantum states exchanged between two endpoints from which a secret key can be extracted. Thus, even though it has some limitations, a correct implementation can deliver keys of the highest security. In this paper, we propose the integration of QKD systems with well-known protocols and methodologies to secure the network’s control plane in an SDN and NFV environment. Furthermore, we experimentally demonstrate a workflow where QKD keys are used together with classically generated keys to encrypt communications between cloud and SDN platforms for setting up a service via secure shell, while showcasing the applicability to other cryptographic protocols.
The advent of cryptographically relevant quantum computers poses an existential threat to classical public-key infrastructure. Quantum Key Distribution (QKD) addresses this challenge by providing information-theoretic security for key establishment, independently of any computational hardness assumption. In this work, the deployment and experimental validation of a metropolitan-scale quantum-secure network between data centers in Milan is reported. The network operates over installed fiber infrastructure and implements a layered architecture integrating QKD hardware, standards-compliant Key Management (KM), and centralized Software-Defined Networking (SDN) orchestration. Dynamic path reconfiguration via active optical switching and trusted-node routing allow automated fail-over solutions. Application-layer validation across diverse protocols and workloads confirms the seamless interoperability of all system components. These results establish the technical and operational readiness of metropolitan QKD networks for production deployment, and offer a replicable blueprint for building quantum-secure communication infrastructure at metropolitan scale.