Current quantum key distribution (QKD) networks focus almost exclusively on transporting secret keys at the highest possible rate. Consequently, they are built as mostly fixed, ad hoc, logically, and physically isolated infrastructures designed to avoid any penalty to the quantum channel. This architecture is neither scalable nor cost-effective and future, real-world deployments will differ considerably. The structure of the MadQCI QKD network presented here is based on disaggregated components and modern paradigms especially designed for flexibility, upgradability, and facilitating the integration of QKD in the security and telecommunications-networks ecosystem. These underlying ideas have been tested by deploying many QKD systems from several manufacturers in a real-world, multi-tenant telecommunications network, installed in production facilities and sharing the infrastructure with commercial traffic. Different technologies have been used in different links to address the variety of situations and needs that arise in real networks, exploring a wide range of possibilities. Finally, a set of realistic use cases has been implemented to demonstrate the validity and performance of the network. The testing took place during a period close to three years, where most of the nodes were continuously active.

Quantum Key Distribution (QKD) is maturing quickly. However, the current approaches to its application in optical networks make it an expensive technology. QKD networks deployed to date are designed as a collection of point-to-point, dedicated QKD links where non-neighboring nodes communicate using the trusted repeater paradigm. We propose a novel optical network model in which QKD systems share the communication infrastructure by wavelength multiplexing their quantum and classical signals. The routing is done using optical components within a metropolitan area which allows for a dynamically any-to-any communication scheme. Moreover, it resembles a commercial telecom network, takes advantage of existing infrastructure and utilizes commercial components, allowing for an easy, cost-effective and reliable deployment.

Quantum Key Distribution is carving its place among the tools used to secure communications. While a difficult technology, it enjoys benefits that set it apart from the rest, the most prominent is its provable security based on the laws of physics. QKD requires not only the mastering of signals at the quantum level, but also a classical processing to extract a secret-key from them. This postprocessing has been customarily studied in terms of the efficiency, a figure of merit that offers a biased view of the performance of real devices. Here we argue that it is the throughput the significant magnitude in practical QKD, specially in the case of high speed devices, where the differences are more marked, and give some examples contrasting the usual postprocessing schemes with new ones from modern coding theory. A good understanding of its implications is very important for the design of modern QKD devices.

Quantum based technologies have been fundamental in our world. After producing the laser and the transistor, the devices that have shaped our modern information society, the possibilities enabled by the ability to create and manipulate individual quantum states opens the door to a second quantum revolution. In this paper we explore the possibilities that these new technologies bring to the Telecommunications industry.

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.

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