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.
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.
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.
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.
Quantum key distribution (QKD) can protect the exchange process of confidential information between communicating parties. By using the basic principles of quantum mechanics and combined with “one-time pad” cipher encryption, information can be unconditionally secure. The BB84 protocol first describes the method of transmitting information by photon polarization state, and it expounds the transmission process of services between trusted relays. However, due to the defects of real experimental devices, there are security vulnerabilities in QKD in a real system. The birth of measurement-device-independent quantum key distribution (MDI-QKD) protocol solves the problem, providing immunity to hacker attacks at the end of the detector. It can enable both sides of the transmission service to establish a connection and generate secret keys through an untrusted relay node to ensure information security. However, the types and properties of link nodes in quantum key distribution network (QKDN) based on partially trusted relay are more complex, which can easily result in network fault. Therefore, how to prevent the impact of failure on QKDN has become an urgent problem. In this paper, we propose a protection scheme for QKDN with partially trusted relays. The method deals with trusted and untrusted relays differently and constructs the working and protection paths of the secret key for each service. It reduces resource conflict between the protection and working paths by establishing a key protection threshold, which realizes the resource trade-off between the two factors. Simulation results show that the scheme provides effective protection to the services, and it improves the stability and reliability of QKDN based on partially trusted relay.
Abstract The rapid advancement of quantum computing poses escalating threats to the cryptographic foundations of blockchain consensus mechanisms deployed in consumer applications. This paper proposes QS-BFT (Quantum-Secured Byzantine Fault Tolerance), a novel quantum-resistant blockchain consensus framework designed to protect consumer-oriented blockchain systems against adversaries operating under an information-theoretically unbounded threat model—that is, adversaries with unlimited classical and quantum computational resources against whom only information-theoretic security (ITS) provides meaningful protection. This is a strictly stronger threat model than the computational security (CS) model assumed by standard post-quantum cryptographic schemes such as lattice-based signatures. QS-BFT integrates Quantum Key Distribution (QKD) networks to address the fundamental vulnerabilities of classical public-key digital signature schemes. By combining QKD with a multilinear hash function family, the framework introduces the MH-USS (Multilinear Hash Unconditionally Secure Signature) scheme, whose signatures are provably unforgeable, non-repudiable, and transferable under ITS, while remaining compatible with deployment on existing consumer devices. To overcome the throughput limitations of classical Byzantine Fault Tolerance approaches such as PBFT, QS-BFT introduces a dual-mode consensus strategy comprising fast mode and standard mode, and permits nodes to vote on empty blocks, thereby eliminating the need for computationally expensive view-change processes. Formal proofs establish the safety and liveness of the protocol under the ITS threat model. Performance evaluations on a local testbed demonstrate that QS-BFT achieves substantially higher throughput and lower latency than PBFT across all tested network configurations. This work advances quantum-resistant blockchain technology by achieving a principled balance between unconditional cryptographic security and practical consensus efficiency.
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.
This paper presents a novel approach to building robust and reliable decentralized quantum sensor networks capable of operating effectively even when confronted with Byzantine faults – malicious or faulty nodes intentionally disrupting network operation. The core of this system leverages quantum key distribution (QKD) for secure key exchange and incorporates advanced consensus algorithms to achieve Byzantine fault tolerance. The proposed mechanism guarantees data integrity and accuracy, mitigating the impact of compromised sensors. We detail the architecture, key components, and the theoretical underpinnings of this system, outlining a pathway towards practical, resilient quantum sensor networks. The key contributions of this work include the integration of QKD with Byzantine fault tolerance specifically tailored for sensor networks, offering a significant advancement over existing approaches that typically treat these challenges separately. Mathematical models and notation are presented for clarity and rigor.