Quantum Key Distribution (QKD) networks are proposed as a solution to ensure information-theoretic security for symmetric key exchange in post-quantum networks. Key generation is limited and variable, hence Quantum Key Pools (QKPs) have been proposed to allow applications a quicker access to quantum keys for secure data exchange. Nevertheless, On-Demand (OD) key relaying can still entail a delay too large for some applications. Therefore, the concept of key provisioning has been proposed to expedite key supply whenever necessary, resulting in Virtual QKPs for non-adjacent QKD nodes. After the implementation of a key pre-provisioning strategy inspired by an approach proposed by other authors, some novel variants are proposed that aim to decrease demand blocking due to the lack of keys, without significantly increasing the delay for key supply. In this work, an experimental study is conducted, where different settings are considered for the simulation parameters (including the QKP capacity). We conclude that the different pre-provisioning strategies allow for a reduction in the blocking probability (calculated for demands and for data) and in the delay, when compared to an OD strategy.
Quantum Key Distribution (QKD) networks are proposed as a solution to ensure information-theoretic security for symmetric key exchange in post-quantum networks. Key generation is limited and variable, hence Quantum Key Pools (QKPs) have been proposed to allow applications a quicker access to quantum keys for secure data exchange. Nevertheless, On-Demand (OD) key relaying can still entail a delay too large for some applications. Therefore, the concept of key provisioning has been proposed to expedite key supply whenever necessary, resulting in Virtual QKPs for non-adjacent QKD nodes. After the implementation of a key pre-provisioning strategy inspired by an approach proposed by other authors, some novel variants are proposed that aim to decrease demand blocking due to the lack of keys, without significantly increasing the delay for key supply. In this work, an experimental study is conducted, where different settings are considered for the simulation parameters (including the QKP capacity). We conclude that the different pre-provisioning strategies allow for a reduction in the blocking probability (calculated for demands and for data) and in the delay, when compared to an OD strategy.
Quantum key distribution (QKD) is experiencing a rapid increase of interest due to its security advantages in the face of quantum computers. However, typical QKD deployments are point-to-point and limited in terms of distance, which significantly restricts their utilization for end-user applications. To overcome these restrictions, trusted relays are adopted as intermediate nodes to allow the transition to QKD networks (QKDNs), where one of the hallmarks is the key management system. In this work, we investigate different key allocation strategies as a method to enhance the performance of key management systems in QKDN from the perspective of key allocation success rate and key delivery delay. We first describe an upgrade model from classical to QKDN at three distinct network layers—quantum, key management, and service. Then, we propose a novel, to our knowledge, key allocation strategy leveraging the benefits of key storage and relaying as a solution to improve the QKDN performance. To achieve this, our method makes use of end-to-end virtual quantum key pools (VQKPs) implemented between non-adjacent nodes requesting key material. We introduce static and dynamic upper and lower threshold limits at the VQKP level, with the dynamic thresholds adapted according to application demand, to control the key distribution in the network and fill the pools ahead of end-user requests. We demonstrate through simulations that the introduction of thresholds achieves performance enhancement and explain the trade-off between the key allocation success rate and key delivery delay evaluation metrics in comparison with different on-demand key allocation strategies.
Quantum key distribution (QKD) allows the distribution of secret keys for quantum-secure communication between two distant parties, vital in the quantum computing era in order to protect against quantum-enabled attackers. However, overcoming rate-distance limits in QKD and the establishment of quantum key distribution networks necessitate key relaying over trusted nodes. This process may be resource-intensive, consuming a substantial share of the scarce QKD key material to establish end-to-end secret keys. Hence, an efficient scheme for key relaying and the establishment of end-to-end key pools is essential for practical and extended quantum-secured networking. In this paper, we propose and compare two protocols for managing, storing, and distributing secret key material in QKD networks, addressing challenges such as the success rate of key requests, key consumption, and overhead resulting from relaying. We present an innovative, fully decentralized key distribution strategy as an alternative to the traditional hop-by-hop relaying via trusted nodes, where three experiments are considered to evaluate performance metrics under varying key demand. Our results show that the decentralized pre-flooding approach achieves higher success rates as application demands increase. This analysis highlights the strengths of each approach in enhancing QKD network performance, offering valuable insights for developing robust key distribution strategies in different scenarios.
Quantum key distribution (QKD) is a symmetric key exchange mechanism designed to enhance the security of current communication systems. Although QKD provides unconditional security, it also comes with deployment challenges. One challenge is the distance limitation between the transmitter and receiver, which restricts the large-scale adoption of QKD. To overcome this, trusted relays are used as intermediate nodes, allowing QKD to evolve from distance-limited point-to-point connections to unlimited QKD networks (QKDN). With an increasing deployment of QKD and a growing number of applications requesting keys, quality of service (QoS) constraints must be set for efficient key resource management to alleviate the risk of rejecting application requests. In this work, we integrate key delivery delay and maximum requested key size as QoS constraints in a novel key allocation algorithm built on three QKDN layers – quantum, key management and service. Moreover, we design key relaying using quantum key pools and virtual quantum key pools as storage mechanisms. We use static and dynamic weights for relay path computation and evaluate their impact on the proposed key allocation strategies with QoS constraints and find that static weights show a good overall performance for QKDN, while performance with dynamic weights varies based on historical key consumption data.
Quantum Key Distribution allows the exchange of symmetric keys with information-theoretic security between adjacent nodes. Key relay techniques in Quantum Key Distribution Networks (QKDNs) address the need for symmetric keys between nodes that are either too distant for establishing a quantum link or separated by intermediate nodes. The Secure Key Rate is limited, which triggers a need to use buffers (Quantum Key Pools) to store keys for later use. The secure key relay uses One-Time Pad, thus the number of links in the route impacts the number of keys used to deliver a pair of symmetric keys. The need for efficient routing algorithms in QKDNs has led to different routing algorithms. This work revisits some routing approaches that have been improved here. Results show that using asymmetrical link costs reduces blocking, a Long Short-Term Memory approach is enhanced by including cross-validation, and finally some strategies to reduce management traffic are proposed.
Quantum key distribution (QKD) provides future-proofed security based on the quantum physics. The end-to-end security services in the fields such as finance, government, and military are mainly carried by optical networks. Limited by technical and economical obstacles of QKD deployment, partially-QKD-deployed optical networks (pQKD-ONs) are much more practical. Key pooling is a technique to decouple keys from the underlying infrastructure for timely key provisioning. However, traditional QKD key provisioning (QKPR) methods are specific to QKD-deployed nodes. In this paper, we propose the pQKD-ON architecture and design the multi-level key pool slicing scheme for key management in pQKD-ONs. Then, we propose a general auxiliary-graph-based QKPR algorithm for key supply in pQKD-ONs. Based on the algorithm, we design four dynamic QKPR policies by adjusting edge weights of the auxiliary graphs including Quantum-Key-Pool-First (QKP-First), Key-Pool-Slice-First (KPS-First), Key-Availability-First (KA-First), and Quantum-Key-Pool-All (QKP-All) policies. We evaluate the performances of the QKPR policies in terms of key consumption, security level, and QKPR latency under two network topologies. Simulation results show that the KA-First policy can achieve 9.9% lower key consumption ratio than the KPS-First policy; the KPS-First policy sacrifices the security level but can achieve lower QKPR latency than the QKP-First and QKP-All policies.
Quantum cryptography (QC) is currently under investigation to build highly secure optical communication networks. QC requires distribution of quantum keys (also called "secret" keys) on separate wavelength channels than those used to transmit the encrypted data. Hence, we propose a quantum-secured passive optical network (QS-PON) that supports both i) the traditional wavelength channels for secured data transmission, and ii) a quantum key distribution network (QKDN) running on separate dedicated wavelengths. The QKDN generates and stores secret keys that are then assigned to users' demands served on traditional PON channels. To generate secret keys, quantum transmitters at the optical network units (ONUs) exchange qubits with a quantum receiver at the optical line terminal (OLT). Then, the generated secret keys are stored in quantum key pools (QKPs) installed at both OLT and the ONUs and assigned to users' demands. Point-to-multipoint QKD systems have been experimentally demonstrated over various forms of quantum access networks (QANs), showing that an efficient mechanism to generate and assign quantum keys based on traffic requests is a critical component of QANs. In this study, we present a new QS-PON architecture, and we propose a dynamic secret-key provisioning (DSKP) algorithm that effectively generates and assigns secret keys from users' demands. Our proposed DSKP algorithm features two phases, the lowest-first secret-key generation (LF-SKG) phase and the hierarchical-clustering secret-key consumption (HC-SKC) phase. In this study, we also provide an analytical model that describes how secret keys are generated and consumed in QKPs. In our illustrative numerical evaluation, we compare our algorithm for secret-key provisioning with a baseline IPACT-based solution in terms of service-rejection ratio, time-slot utilization, and guard- and relay-time saving. Results show that DSKP reduces service-rejection ratio and guard- and relay-time of about 16% and 39.54%, respectively.