Due to the intrinsic point-to-point characteristic of quantum key distribution (QKD) systems, it is necessary to study and develop QKD network technology to provide a secure communication service for a large-scale of nodes over a large area. Considering the quality assurance required for such a network and the cost limitations, building an effective mathematical model of a QKD network becomes a critical task. In this paper, a flow-based mathematical model is proposed to describe a QKD network using mathematical concepts and language. In addition, an investigation on QKD network topology evaluation was conducted using a unique and novel QKD network performance indicator, the Information-Theoretic Secure communication bound, and the corresponding linear programming-based calculation algorithm. A large number of simulation results based on the SECOQC network and NSFNET network validate the effectiveness of the proposed model and indicator.
Due to the intrinsic point-to-point characteristic of quantum key distribution (QKD) systems, it is necessary to study and develop QKD network technology to provide a secure communication service for a large-scale of nodes over a large area. Considering the quality assurance required for such a network and the cost limitations, building an effective mathematical model of a QKD network becomes a critical task. In this paper, a flow-based mathematical model is proposed to describe a QKD network using mathematical concepts and language. In addition, an investigation on QKD network topology evaluation was conducted using a unique and novel QKD network performance indicator, the Information-Theoretic Secure communication bound, and the corresponding linear programming-based calculation algorithm. A large number of simulation results based on the SECOQC network and NSFNET network validate the effectiveness of the proposed model and indicator.
With the growing complexity of quantum key distribution (QKD) network structures, aforehand topology design is of great significance to support a large-number of nodes over a large-spatial area. However, the exclusivity of quantum channels, the limitation of key generation capabilities, the variety of QKD protocols and the necessity of untrusted-relay selection, make the optimal topology design a very complicated task. In this research, a hybrid QKD network is studied for the first time from the perspective of topology, by analyzing the topological differences of various QKD protocols. In addition, to make full use of hybrid networking, an analytical model for optimal topology calculation is proposed, to reach the goal of best secure communication service by optimizing the deployment of various QKD devices and the selection of untrusted-relays under a given cost limit. Plentiful simulation results show that hybrid networking and untrusted-relay selection can bring great performance advantages, and then the universality and effectiveness of the proposed analytical model are verified.
Quantum Key Distribution (QKD) is a foundational method for the secure generation and distribution of cryptographic keys between network nodes, relying on quantum mechanical principles to provide information-theoretic security. As quantum computing continues to advance, the development of quantum communication networks requires the implementation of complex and secure architectures. However, the deployment of such networks demands considerable financial, technical, and human resources. In this context, simulation tools are essential, as they enable researchers to validate theoretical models, optimize network design, and identify potential vulnerabilities without the need for costly physical infrastructure. The goal of the research was to evaluate the efficiency and accuracy of QNET simulation tool by comparing the outcomes of developed simulation models with empirical data from real QKD networks. While the results in some cases closely aligned indicating a high level of accuracy in modeling QKD networks noticeable discrepancies were observed in certain scenarios. Such an approach not only facilitates more accurate modeling and planning but also promotes the development of scalable, cost effective, and secure quantum communication systems.
The wide range of supported services in modern telecommunication networks has increased the demand for highly secure means of communication. Common security frameworks based on the computational security model are expected to become insecure due to significant advances in quantum computing. Quantum key distribution (QKD), a new secret key agreement primitive, enables long-anticipated practical information-theoretical security (ITS). Over the past two decades, academic and industrial communities have devoted their time and resources to developing QKD-based networks that can distribute and serve ITS keys to remote parties. However, because the availability of QKD network testbeds to the larger research community is limited and the deployment of such systems is costly and difficult, progress in this area is noticeably slow. To address this problem and spur future development and education, we provide a valuable, unique tool for simulating a QKD network. The tool is essential to testing novel network management methodologies applied to large-scale QKD networks. The simulator model contained in the tool was validated by simulating a network with six nodes and three pairs of users. The results indicate that the designed functional elements operate correctly.
Quantum Key Distribution (QKD), based on the laws of physics rather than the computational \ncomplexity of mathematical problems, provides a secure way of establishing symmetrical binary \nkeys between two geographically distant users. The keys are secure from eavesdropping during \ntransmission and QKD ensures that any third party’s knowledge of the key is reduced to a \nminimum. In recent years, a noticeable progress in the development of quantum equipment has \nbeen reflected through a number of successful demonstrations of QKD technology. While they \nshow the great achievements of QKD, many practical difficulties still need to be resolved, such as \nto provide better service differentiation. These networks are characterized as being multihop in \nnature where the consumption key rate is often higher than the charging key rate, which means that \nthe links are available for a limited period of time only. Such features impose several challenges \non the effective modeling and evaluation of reliability as well as finding appropriate Quality \nof Service (QoS) solution. This thesis focuses on research in the field of QKD for securing \nreal-time communication by supporting QoS in QKD networks including a novel QoS model \nand novel distributed reactive routing protocol to achieve high-level scalability and minimize the \nconsumption of key material used for securing routing data. \nAs research in QKD networks grows larger and more complex, the need for highly accurate and \nscalable simulation technologies becomes important to assess the practical feasibility and foresee \ndifficulties in the practical implementation of theoretical achievements. Due to the specificity of \nQKD link which requires optical/quantum and Internet connection between the network nodes, it \nis very costly to deploy a complete testbed containing multiple network hosts and links to validate \nand verify a certain network algorithm or protocol. The network simulators in these circumstances \nsave a lot of money and time in accomplishing such task. A simulation environment offers the \ncreation of complex network topologies, a high degree of control and repeatable experiments, \nwhich in turn allows researchers to conduct exactly the same experiments and confirm their results. \nThis thesis describes the design and implementation of QKD network simulation module which \nwas developed in the network simulator of version 3 (NS-3). The module supports simulation \nof QKD network in overlay mode or in a single TCP/IP mode. Therefore, it can be used for \nsimulation of other network technologies regardless of QKD. \nImplemented simulation model was used for verification of proposed QoS solution. A number \nof simulations were performed. The obtained data have confirmed the primary thesis of this study, \nthat it is possible to use real-time applications in QKD networks.
A quantum key distribution (QKD) network is an infrastructure that allows the realization of the key distribution cryptographic primitive over long distances and at high rates with information-theoretic security.In this work, we consider QKD networks based on trusted repeaters from a topology viewpoint, and present a set of analytical models that can be used to optimize the spatial distribution of QKD devices and nodes in specific network configurations in order to guarantee a certain level of service to network users, at a minimum cost.We give details on new methods and original results regarding such cost minimization arguments applied to QKD networks.These results are likely to become of high importance when the deployment of QKD networks will be addressed by future quantum telecommunication operators.They will therefore have a strong impact on the design and requirements of the next generation of QKD devices.
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].