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arXiv:2302.07688 · Journal of Optical Communications and Networking

Distributed information-theoretical secure protocols for quantum key distribution networks against malicious nodes

Yi Luo, Qiong Li, Haokun Mao

Published Aug 7, 2024• 10 citations
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Abstract

Quantum key distribution (QKD) networks are expected to enable information-theoretical secure (ITS) communication over a large-scale network. Most research on relay-based QKD networks assumes all relays or nodes are completely trustworthy. However, this assumption is unreasonable because the malicious behavior of even a single node can undermine the security of the entire network. Currently, there is no method to directly distinguish between honest nodes and malicious nodes. Moreover, the status of nodes as honest or malicious can be dynamic. Therefore, a solution is needed that can withstand a certain proportion of malicious nodes in QKD networks. We propose a novel paradigm, inspired by distributed systems, to address the active and passive attacks by collaborating with malicious nodes in QKD networks. First, regarding security, we propose the ITS distributed authentication scheme, which additionally ensures two crucial security properties to QKD networks: identity unforgeability and non-repudiation. Second, concerning correctness, we propose an ITS fault-tolerant consensus scheme based on our ITS distributed authentication to ensure global consistency. This enables participating nodes to collaborate correctly and complete end-to-end key distribution within a constant number of communication rounds. Through our simulation, we have shown that our scheme exhibits a significantly lower growth trend in key consumption compared to the original end-to-end pre-shared keys scheme. For instance, in larger networks, such as when the number of nodes is 80, our scheme’s key consumption is only 13.1% of the pre-shared keys scheme.

DOI
10.1364/jocn.530575

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Quantum key distribution (QKD) networks are expected to enable information-theoretical secure (ITS) communication over a large-scale network. Most research on relay-based QKD networks assumes all relays or nodes are completely trustworthy. However, this assumption is unreasonable because the malicious behavior of even a single node can undermine the security of the entire network. Currently, there is no method to directly distinguish between honest nodes and malicious nodes. Moreover, the status of nodes as honest or malicious can be dynamic. Therefore, a solution is needed that can withstand a certain proportion of malicious nodes in QKD networks. We propose a novel paradigm, inspired by distributed systems, to address the active and passive attacks by collaborating with malicious nodes in QKD networks. First, regarding security, we propose the ITS distributed authentication scheme, which additionally ensures two crucial security properties to QKD networks: identity unforgeability and non-repudiation. Second, concerning correctness, we propose an ITS fault-tolerant consensus scheme based on our ITS distributed authentication to ensure global consistency. This enables participating nodes to collaborate correctly and complete end-to-end key distribution within a constant number of communication rounds. Through our simulation, we have shown that our scheme exhibits a significantly lower growth trend in key consumption compared to the original end-to-end pre-shared keys scheme. For instance, in larger networks, such as when the number of nodes is 80, our scheme’s key consumption is only 13.1% of the pre-shared keys scheme.
Quantum key distribution (QKD) networks is expected to provide information-theoretical secured (ITS) communication over long distances. QKD networks based trusted relay architecture are now the most widely used scheme in practice. However, it is an unrealistic assumption that all relays are fully trustable in complex networks. In the past, only a few studies have theoretically analyzed the case of passive eavesdropping attack by dishonest relays and corresponding defense method. However, we have found that active attacks by dishonest relays can be more threatening. With the consideration of passive and active attacks, we treat dishonest relays as Byzantine nodes and analyzes the upper limit of Byzantine nodes that the QKD network can accommodate. In this paper, we propose an ITS Byzantine-fault tolerance (BFT) QKD network scheme to achieve end-to-end key distribution based on point-to-point QKD links. To ensure consistency and provide BFT ability in the QKD network, we design an ITSBFT-consensus protocol for this network scheme. To ensure the information-theoretic security of consensus, we design a temporary signature scheme based on point-to-point QKD link keys. To prevent Byzantine nodes from disrupting the execution process of key distribution, we design an end-to-end key distribution scheme combined with consensus. We theoretically analyze proposed ITSBFT-QKD network scheme from four aspects: QKD key distribution security, temporary signature security, consensus security, and leader election fairness. The simulation result proved the feasibility and demonstrate the performance.
Information-theoretic secure (ITS) authentication is an essential part of a quantum key distribution (QKD) system. In the QKD network, the authentication scheme based on the ITS QKD keys pre-shared by the QKD system. However, such a scheme is subject to the limitation that consumes a significant amount of authentication keys when the scale and communication requirements of QKD networks grow. To address the issue, we propose an ITS group authentication scheme for QKD networks that consumes considerably fewer keys. In our scheme, multiple QKD network nodes collaborate and complete the authentication as a group. Compared to the pre-shared keys authentication scheme, our scheme reduces the complexity of authentication key consumption from$O\left ({N^{2}d }\right) tototoO\left ({N }\right) ,where, where,whereN isthenumberofnodesandis the number of nodes andisthenumberofnodesandd $is the average path length of the network topology. The security of the proposed scheme is analyzed in detail and simulation experiments are conducted to demonstrate our scheme’s effectiveness for varying networks scales and communication requirements.
This paper proposes a novel approach to distributed consensus that leverages quantum key distribution (QKD) for Byzantine fault tolerance. Traditional consensus algorithms struggle to guarantee agreement in the face of malicious actors introducing Byzantine faults. This work introduces a framework where a shared secret, established via QKD, serves as the foundation for a consensus protocol. The inherent cryptographic properties of QKD – specifically its ability to detect eavesdropping – are exploited to identify and neutralize malicious nodes attempting to disrupt the consensus process. We demonstrate that this combination offers a fundamentally more secure and efficient solution compared to classical approaches. The core of our system relies on the creation of a quantum-secured shared key, denoted as *K*, and the subsequent implementation of a consensus protocol designed to operate on this key. This protocol incorporates mechanisms for key verification and anomaly detection, providing robust resilience against Byzantine faults. The theoretical analysis presented highlights the advantages of this approach in terms of security and efficiency. We define the following key variables: *n* - number of nodes in the network; *f* - maximum number of faulty nodes; *m* - number of correct nodes; *si* - the state of node *i* (1 if active, 0 if faulty); *K* - the quantum key shared among the nodes; *ri,j* - the raw key shared between nodes *i* and *j*; *Ei,j* - the error rate observed between nodes *i* and *j* during QKD; *σi,j* - the quantum state used for key exchange between nodes *i* and *j*; *Ci,j* - the ciphertext generated during the QKD process; *Di,j* - the decrypted ciphertext between nodes *i* and *j*; *Hi,j* - the hash value calculated based on the decrypted ciphertext. The system's robustness is directly proportional to the level of security provided by QKD and the effectiveness of the consensus protocol in detecting and isolating faulty nodes.
Abstract Secure key distribution is crucial for maintaining communication confidentiality in networks with multiple communicating partners. Asymmetric key algorithms are vulnerable to quantum attacks because of the computational advantage offered by quantum computers, whereas symmetric key algorithms with sufficiently large keys remain comparatively more resistant. Quantum Key Distribution (QKD) has emerged as a promising quantum-secure key distribution technique based on the principles of quantum physics. However, practical QKD networks often rely on relay nodes to extend communication distance, and malicious relay nodes can compromise quantum keys during the relaying process. This study proposes a secure key relaying approach based on Shamir's Secret Sharing to mitigate this vulnerability. The proposed method uses a probabilistic behavioural model to assess relay nodes according to their curiosity and collaboration tendencies. By splitting a quantum key into multiple shares and routing them through paths with minimum compromise risk, the approach reduces exposure to malicious or colluding relay nodes. The proposed algorithm assigns risk to network paths by evaluating node-level curiosity and collaboration potential, determines the appropriate number of shares, and selects secure routing paths to minimise key compromise. The study further analyses the parameters influencing the ideal number of shares for a given network, thereby offering a resilient mechanism for quantum-safe communication in QKD networks with malicious relay nodes.
Quantum key distribution (QKD) networks promise information-theoretic security for multiple nodes by leveraging the fundamental laws of quantum mechanics. In practice, QKD networks require dedicated routing protocols to coordinate secure key distribution among distributed nodes. However, most existing routing protocols operate under the assumption that all relay nodes are honest and fully trustworthy, an assumption that may not hold in realistic scenarios. Malicious nodes may tamper with routing updates, causing inconsistent key-state views or divergent routing plans across the network. Such inconsistencies increase routing failure rates and lead to severe wastage of valuable secret keys. To address these challenges, we propose a distributed routing framework that combines two key components: (i) Causal Consistency Key-State Update, which prevents malicious nodes from propagating inconsistent key states and routing plans; and (ii) Trust-Aware Multi-path Flow Optimization, which incorporates trust metrics derived from discrepancies in reported states into the path-selection objective, penalizing suspicious links and filtering fabricated demands. Across 50-node topologies with up to 30% malicious relays and under all three attack modes, our protocol sustains a high demand completion ratio (DCR) (mean 0.90, range 0.81-0.98) while keeping key utilization low (16.6 keys per demand), decisively outperforming the baselines-Multi-Path Planned (DCR 0.48, 30.8 keys per demand) and OSPF (DCR ≤0.12, 296 keys per demand; max 1601). These results highlight that our framework balances reliability and efficiency, providing a practical and resilient foundation for secure QKD networking in adversarial environments.
This paper presents a novel approach to distributed consensus protocols leveraging quantum entanglement and Byzantine fault tolerance. The core claim is that quantum entanglement can provide secure and efficient agreement among nodes even in the presence of malicious actors. We propose a mechanism that utilizes quantum key distribution (QKD) to establish shared entanglement between participating nodes. Subsequent quantum measurements identify faulty nodes, informing a robust consensus algorithm built upon majority voting and entanglement-based error correction. The potential advantages of this combined approach – enhanced security and efficiency compared to traditional classical methods – are explored. The research addresses the critical challenge of achieving reliable consensus in distributed systems susceptible to Byzantine attacks. This work introduces a new paradigm for consensus, potentially leading to more resilient and secure distributed applications.