Quantum Key Distribution (QKD) is a technique for sharing encryption keys between two adjacent nodes in an unconditionally secure manner based on quantum theory. From the viewpoint of network system research, QKD is considered to be a building block for providing secure link communication in network systems. Although the communication distance is subject to a limitation attributable to the QKD fundamentals, recent research and some QKD field trials of “key relaying” over a “QKD network” are overcoming this limitation. It also enables each node on the QKD network to exchange encryption keys with arbitrary nodes on the QKD network. However, the previous research didn't address a routing method on the QKD network in detail. This paper focuses on the routing issues on the QKD network, clarifies the requirements of the routing protocol, and proposes a routing solution designed for the key relaying on the QKD network. The proposed routing solution consists of 4 components: (1) a node interface architecture addressing both encrypted and unencrypted traffics, (2) a path selection algorithm based on the number of keys, (3) an IP address assignment scheme connecting unencrypted interfaces and encrypted interfaces, and (4) a routing protocol deployment method consuming no extra keys. The proposed routing solution allows the QKD network to select a suitable key relaying path according to the QKD system condition and to reduce the extra key consumption, which optimizes the key utilization on the QKD network. The proposed routing solution was implemented with a network emulating QKD technology and evaluated. The evaluation result shows that the proposed routing solution could select a path that stores enough keys, which is suitable for a QKD network. Additional impact analysis reveals that the proposed routing solution could save up to 52% of key consumption depending on the QKD key sharing speed and the routing protocol configuration.
Quantum Key Distribution (QKD) is a technique for sharing encryption keys between two adjacent nodes in an unconditionally secure manner based on quantum theory. From the viewpoint of network system research, QKD is considered to be a building block for providing secure link communication in network systems. Although the communication distance is subject to a limitation attributable to the QKD fundamentals, recent research and some QKD field trials of “key relaying” over a “QKD network” are overcoming this limitation. It also enables each node on the QKD network to exchange encryption keys with arbitrary nodes on the QKD network. However, the previous research didn't address a routing method on the QKD network in detail. This paper focuses on the routing issues on the QKD network, clarifies the requirements of the routing protocol, and proposes a routing solution designed for the key relaying on the QKD network. The proposed routing solution consists of 4 components: (1) a node interface architecture addressing both encrypted and unencrypted traffics, (2) a path selection algorithm based on the number of keys, (3) an IP address assignment scheme connecting unencrypted interfaces and encrypted interfaces, and (4) a routing protocol deployment method consuming no extra keys. The proposed routing solution allows the QKD network to select a suitable key relaying path according to the QKD system condition and to reduce the extra key consumption, which optimizes the key utilization on the QKD network. The proposed routing solution was implemented with a network emulating QKD technology and evaluated. The evaluation result shows that the proposed routing solution could select a path that stores enough keys, which is suitable for a QKD network. Additional impact analysis reveals that the proposed routing solution could save up to 52% of key consumption depending on the QKD key sharing speed and the routing protocol configuration.
Quantum key distribution (QKD) technology can establish unconditional secure keys between two communicating parties. Although this technology has some inherent constraints, such as the distance and point-to-point mode limits, building a QKD network with multiple point-to-point QKD devices can overcome these constraints. Considering the development level of current technology, the trust relaying QKD network is the first choice to build a practical QKD network. However, the previous research didn’t address a routing method on the trust relaying QKD network in detail. This paper focuses on the routing issues, builds a model of the trust relaying QKD network for easily analysing and understanding this network, and proposes a dynamical routing scheme for this network. From the viewpoint of designing a dynamical routing scheme in classical network, the proposed scheme consists of three components: a Hello protocol helping share the network topology information, a routing algorithm to select a set of suitable paths and establish the routing table and a link state update mechanism helping keep the routing table newly. Experiments and evaluation demonstrates the validity and effectiveness of the proposed routing scheme.
Since the QKD network can overcome the distance limitation and expand the point-to-point QKD system to a multi-user key distribution system, some testing QKD networks have been built. However, all of this previous research seldom focused on the routing mechanism of QKD network in detail. Therefore, this paper focuses on the routing issue in trust relaying QKD network, builds a model of the trust relaying QKD network and proposes a secret-key-aware routing method. In our method, a dynamic model for the residual local key is proposed to forecast the residual local key quantity of each QKD link more accurately, and the cost of QKD link and relaying path are defined by multiple affecting factors, e.g. the generation, consumption rate and the local key depletion index. The proposed method is implemented and evaluated in a simulation environment. The simulation results show that our routing method can increase the success rate of key exchange, make all the QKD links participate key exchange with almost equal opportunity to achieve load balance, and trade off the local key generation and consumption of each QKD link. Therefore, our proposed method can contribute to effectively improve the holistic performance of the trust relaying QKD network.
Quantum key distribution (QKD) protocols generate a same secret key at two nodes which are at different locations. Such key is used to encrypt and decrypt messages for unconditionally secure communications through a classical channel. Originally, QKD protocols are designed to work between two nodes which are directly connected through a point-to-point quantum channel. Currently, commercial QKD systems have limited range and key rate. To increase key rate and extend range, the key generated by QKD at one end node is relayed hop-by-hop to the other end node through multiple trusted nodes. In a QKD network with multiple pairs of communicating nodes, routing deals with the issue of deciding for each pair, which trusted nodes are used to form a path connecting the end nodes. This paper presents an overview of QKD and highlights the differences between QKD routing as compared to classical routing. The challenges of QKD routing are presented. Existing works dealing with the challenges are surveyed. This paper ends with a discussion on remaining research issues.
Quantum Key Distribution (QKD) is a technique for sharing encryption keys between two adjacent nodes. It provides unconditional secure communication based on the laws of physics. From the viewpoint of network research, QKD is considered to be a component for providing secure communication in network systems. A QKD network enables each node to exchange encryption keys with arbitrary nodes. However previous research did not focus on the processing speed of the key management method essential for a QKD network. This paper focuses on the key management method assuming a high-speed QKD system for which we clarify the design, propose a high-speed method, and evaluate the throughput. The proposed method consists of four modules: (1) local key manager handling the keys generated by QKD, (2) one-time pad tunnel manager establishing the transparent encryption link, (3) global key manager generating the keys for application communication, and (4) web API providing keys to the application. The proposed method was implemented in software and evaluated by emulating QKD key generation and application key consumption. The evaluation result reveals that it is capable of handling the encryption keys at a speed of 414 Mb/s, 185 Mb/s, 85 Mb/s and 971 Mb/s, for local key manager, one-time pad tunnel manager, global key manager and web API, respectively. These are sufficient for integration with a high-speed QKD system. Furthermore, the method allows the high-speed QKD system consisting of two nodes to expand corresponding to the size of the QKD network without losing the speed advantage.
With the advent of powerful quantum computers, an emerging quantum-resilient security mechanism within existing networks is crucial. Thus, Quantum Key Distribution (QKD), which generates symmetric secret keys with Information-Theoretical Security (ITS) for secure point-to-point communication, is present as a solution. Despite QKD’s potential, its deployment is challenging due to significant investment and infrastructure requirements. Using state-of-the-art technology, the maximum distance between nodes is limited to hundreds of kilometers, necessitating multiple nodes to relay keys. For now, QKD Network (QKDN) relies on software-defined networking (SDN) and a central orchestrator, but this centralized approach has limitations. Hence, the main challenge is to select an efficient path between key relays to avoid communication failure. To address these challenges, a more distributed approach could be envisioned. In this paper, we propose to leverage one of the distributed routing protocols, OSPF, to redefine and improve the current architecture. We propose a novel QKDN-based OSPF (Open Shortest Path First) architecture for efficient key relay routing, offering a completely different dimension to the overall network management: we modify QKDN architecture to exploit the OSPF networks and present a QKD-enabled OSPF version capable of computing the best path for key relay, offering a cost-effective and scalable solution for widespread QKD adoption.
Quantum key distribution (QKD) is an encrypted communication technique based on the principles of quantum mechanics that ensures communication security by exploiting the properties of quantum states. Currently, the transmission efficiency of the QKD system is low. Trusted relay technology is used to solve this problem and achieve long-distance transmission. However, trusted relaying alone cannot decrypt the issues of poor link stability and the low utilization of key resources. To further optimize the system performance, we propose a dynamic routing algorithm. One of the improvement schemes includes the following: firstly, an adjustable-size quantum key pool (QKP) is designed, which can dynamically adjust the size of the refreshing pool according to the actual demand. Secondly, the utilization of key resources is improved by using the residual quantum key model to dynamically obtain the remaining key amount in the QKP and set the key amount threshold. We calculate the link-blocking probability and track the blocking intensity and blocking entry by combining the Poisson process, thus realizing the evaluation of the link stability. Finally, the number of remaining keys in the QKP and the link-blocking probability combine with the random wandering model as the basis of the route selection for the QKD dynamic routing algorithm to achieve efficient key path selection. We validated the algorithm by comparing it with other algorithms on the Mininet simulation platform, and the algorithm proved to have a better performance in terms of congestion avoidance, delay reduction, and improved QKD efficiency. This scheme provides a novel and efficient way to solve the problems in existing QKD systems. It effectively improves the transmission efficiency and strengthens the system’s security by dynamically obtaining the critical volume, accurately evaluating the link state, and selecting the optimal critical path.