Quantum Key Distribution (QKD) networks allow multiple users to generate and share secret quantum keys with unconditional security. Although many schemes of QKD networks have been presented, they are only concentrated on the system realization and physical implementations. For the complete practical quantum network, a succinct theoretic model that systematically describes the working processes from physical schemes to key process protocols, from network topology to key management, and from quantum communication to classical communication is still absent. One would hope that research and experience have shown that there are certain succinct model in the design of communication network. With demonstration of the different QKD links and the four primary types of quantum networks including probability multiplexing, wavelength multiplexing, time multiplexing and quantum multiplexing, we suggest a layer model for QKD networks which will be compatible with different implementations and protocols. We divide it into four main layers by their functional independency while defining each layer's services and responsibilities in detail, orderly named quantum links layer, quantum networks layer, quantum key distribution protocols process layer, and keys management layer. It will be helpful for the systematic design and construction of real QKD networks.
Quantum Key Distribution (QKD) networks allow multiple users to generate and share secret quantum keys with unconditional security. Although many schemes of QKD networks have been presented, they are only concentrated on the system realization and physical implementations. For the complete practical quantum network, a succinct theoretic model that systematically describes the working processes from physical schemes to key process protocols, from network topology to key management, and from quantum communication to classical communication is still absent. One would hope that research and experience have shown that there are certain succinct model in the design of communication network. With demonstration of the different QKD links and the four primary types of quantum networks including probability multiplexing, wavelength multiplexing, time multiplexing and quantum multiplexing, we suggest a layer model for QKD networks which will be compatible with different implementations and protocols. We divide it into four main layers by their functional independency while defining each layer's services and responsibilities in detail, orderly named quantum links layer, quantum networks layer, quantum key distribution protocols process layer, and keys management layer. It will be helpful for the systematic design and construction of real QKD networks.
Secure networks composed of optical networks and quantum key distribution (QKD) are considered in this paper. A network layer structure is defined to focus on issues important with respect to the QKD network layer that controls QKD links and supplies a secure key for message transmission. A multiple-user QKD network layer can be constructed with timing synchronization, secure key sharing between indirectly connected nodes with switched QKD systems and key relays, and key management to control the volume of key generation and supply in response to the demand from optical network nodes.
Similar to the Internet, Quantum Key Distribution (QKD) networks typically have diverse participants, such as users, operators, and infrastructure builders. In order to achieve loose functional coupling, a multi-layer structure is frequently indispensable. Nevertheless, once the architecture of the QKD network is designed, further expansion and modification prove to be extremely challenging. To address this issue, a QKD network architecture based on virtual Quantum Key Distribution (VQKD) is proposed. In this architecture, all devices at both ends that are capable of providing consistent quantum keys are regarded as a pair of quantum key distribution devices. The bottom layer is real QKD, while all other layers are virtual QKD. All real and virtual QKDs provide quantum keys to the upper layers. This network structure is an iterative one, and theoretically, the number of layers in a quantum key distribution network can be infinitely increased based on actual needs. In this paper, we present a practical application case. This case addresses the actual needs of network operators, network service providers, and those involved in user network construction. We have designed a three-layer quantum secure communication network exchange structure that is suitable for network infrastructure developers, network operators, and those involved in user network construction. Network infrastructure developers, network operators, and users can carry out network construction, network operation, and user network construction at different network layers, realizing a loosely coupled hierarchical design of quantum secure communication networks. This model can dynamically increase or decrease the number of quantum network exchange layers based on actual needs, without affecting the network exchange of quantum secure communication networks, demonstrating strong versatility and adaptability.
A global Quantum Key Distribution (QKD) network, as the one developed in the European project SECOQC [1] is an infrastructure capable of realizing long-distance secret key establishment with information-theoretic security. Due to the specificity of their physical layer, the structure and the principle of operation of QKD networks will however significantly differ from the solutions adopted for “classical ” networks. The deployment of QKD networks is indeed far from being straightforward: it implies the con-ception of a network architecture connecting multiple users that may possibly be very far away from each other, all of this while QKD links are currently point-to-point only and intrinsically limited in distance. We will describe the logical architecture we have adopted for QKD networks with the SECOQC project. It is based on the original concept of maintaining a dedicated “network of secrets ” in order to distribute and manage the secret key material produced by QKD devices. We will alo present specific issues related to the development of a stack of network protocols adapted to the specific constraints of such infrastructures [2]. We have also considered QKD networks from a topology viewpoint and study analytically how cost minimization arguments impact on the optimal working points of individual QKD links [3]. We show in particular that, in the perspective of QKD networks, individual QKD links should be operated at an optimal working distance that can be significantly shorter than the maximum distance imposed by detector dark counts. We explain why such results motivate the research of new experimental compromise in practical QKD systems, and illustrate that point by considering the example of the recently developped DPSK QKD system [4].
Quantum key distribution (QKD) constitutes a symmetric secret key negotiation protocol capable of maintaining information-theoretic security. Given the recent advances in QKD networks, they have evolved from academic research to some preliminary applications. A QKD network consists of two or more QKD nodes interconnected by optical fiber or free space links. The secret keys are negotiated between any pair of QKD nodes, and then they can be delivered to multiple users in various areas for ensuring long-term protection and forward secrecy. We commence by introducing the QKD basics, followed by reviewing the development of QKD networks and their implementation in practice. Subsequently, we describe the general QKD network architecture, its elements, as well as its interfaces and protocols. Next, we provide an in-depth overview of the associated physical layer and network layer solutions, followed by the standardization efforts as well as the application scenarios associated with QKD networks. Finally, we discuss the potential future research directions and provide design guidelines for QKD networks.
Quantum Key Distribution (QKD) is one of the major cryptographic solutions to tackle the security threats associated to future computational advances, in particular those coming from quantum computing. At the most simple level, QKD can be seen as a highly secure source of symmetric secret keys in two separated places. Nonetheless, the lack of standardization and the strong requirements from the physical layer makes this technology very difficult to integrate in existing infrastructure.However, the success of QKD networks radically depends on the degree in which they can be adopted in the existing infrastructure, and it is a must that it happens via standard protocols and interfaces. The flexibility of novel network paradigms, like Software-Defined Networking (SDN), allows for a faster adoption of new concepts, hardware and services in telecommunications networks. This paradigm can be used for quantum communications, allowing for a fast and scalable deployment of quantum technologies and services in the telecommunications network to a degree that was simply impossible in previous schemes, where the different network devices and their connections should be modified, one by one, to create a quantum communications channel.This tutorial provides an introduction to existing QKD technologies and networks, followed by a descriptive explanation on how SDN principles can be utilized to abstract and integrate QKD systems as part of the network management. This will help to reduce the time-to-market for quantum technologies, and also will make quantum cryptography available as a service to be capitalized by the network operators.
Abstract The fundamental architecture and functions of secure key management in a quantum key distribution (QKD) network with enhanced universal interfaces for smooth key sharing between arbitrary two nodes and enabling multiple secure communication applications are proposed. The proposed architecture consists of three layers: a quantum layer, key management layer and key supply layer. We explain the functions of each layer, the key formats in each layer and the key lifecycle for enabling a practical QKD network. A quantum key distribution-advanced encryption standard (QKD-AES) hybrid system and an encrypted smartphone system were developed as secure communication applications on our QKD network. The validity and usefulness of these systems were demonstrated on the Tokyo QKD Network testbed.