This paper explores the application of quantum error correction (QEC) codes to enhance the security and resilience of blockchain technology. Traditional blockchains are vulnerable to attacks that exploit vulnerabilities in their distributed ledger systems. The core challenge lies in the immutable nature of the blockchain, where a single compromised node can potentially disrupt the entire network. This research proposes leveraging the powerful error-correcting capabilities of QEC codes to safeguard blockchain data. Specifically, we examine the encoding and decoding processes using various QEC codes, focusing on their ability to detect and correct errors introduced by malicious actors. The integration of QEC codes into the blockchain architecture can significantly improve its tolerance to attacks, ensuring data integrity and maintaining the trust inherent in the blockchain system. We present a framework for implementing QEC within blockchain transactions and discuss the potential performance implications. The primary goal is to demonstrate that QEC codes offer a viable path towards a more robust and secure blockchain ecosystem.
This paper proposes a novel distributed consensus algorithm inspired by quantum mechanics, termed the Quantum-Inspired Distributed Consensus Algorithm with Measurement-Based Feedback (QIDCA-MBF). The core idea is to utilize the principles of quantum superposition to accelerate the convergence of distributed consensus in challenging network environments, particularly those prone to node failures. Unlike traditional consensus algorithms, QIDCA-MBF employs probabilistic representations of proposed values within each node, mimicking the concept of quantum superposition. A key innovation is the incorporation of measurement-based feedback, modeled after quantum measurement, to collapse these superpositions and guide the nodes towards a shared consensus value. This feedback mechanism dynamically adapts to the network topology and detects node failures, significantly enhancing the algorithm's robustness and convergence speed. The algorithm is formulated based on a modified averaging process, incorporating probabilistic weights derived from the superposition states. Simulation results demonstrate the effectiveness of QIDCA-MBF in achieving consensus rapidly and reliably, outperforming conventional distributed consensus protocols under various failure scenarios. The algorithm's adaptability and resilience make it a promising candidate for applications in decentralized systems, sensor networks, and blockchain technologies.
Mohammad Reehan Nawaz, Mohammad Afaque, Anzer Hussain, Dr. Anand Prakash
The emergence of quantum computing poses a significant threat to classical cryptographic mechanisms such as RSA and Elliptic Curve Cryptography that are widely used to secure email communication. Traditional secure email systems rely on classical public-key infrastructure and therefore lack resilience against quantum attacks. This paper presents QuMail, a quantum-secure email client that integrates BB84-based Quantum Key Distribution (QKD) simulation, CRYSTALS-Kyber post-quantum cryptography (PQC), and blockchain-based audit logging within a unified architecture. The proposed system operates entirely at the application layer and remains compatible with existing email infrastructures using standard SMTP and IMAP protocols without requiring any server-side modification. A modular prototype was implemented using IBM Qiskit for quantum key generation and hybrid cryptographic techniques for secure message transmission. Experimental evaluation demonstrates an average latency of 120–180 ms for QKD key generation and 20–30 ms for Kyber-based encryption while maintaining minimal overhead for email transmission. The results demonstrate the feasibility of integrating quantum-resilient security mechanisms into existing email systems and highlight the potential of hybrid QKD–PQC architectures for next-generation secure communication platforms.
We study the impact that two miners equipped with quantum computers purpose-built for quantum Bitcoin mining will have on the 51% attack threshold of the Bitcoin network, given that the miners are playing a competitive game against each other to be the first to mine a block. We extend an existing game-theoretic framework for Bitcoin mining and compute the resultant payoff matrices. From these payoff matrices, we determine optimal quantum mining strategies for two non-colluding and aggressive quantum miners with multiple opportunities at finding a valid block in an otherwise classical Bitcoin network. We show that these optimal quantum mining strategies have a negligible effect on the 51% attack threshold. The novelty of our work is the inclusion of the Aggressive Quantum Mining Strategy and the realistic approach of allowing the quantum miners to restart their search if their measurements do not yield a valid block when determining the optimal quantum mining strategies. Our result is important for evaluating quantum-mining threats on cryptocurrencies based on Proof-of-Work, e.g. Bitcoin
The paper addresses entity authentication in quantum key distribution (QKD) systems as a decisive condition of their practical security. It is shown that the information-theoretic security of quantum key agreement does not eliminate the need to authenticate the communicating parties: an unauthenticated classical channel leaves the system exposed to the man-in-the-middle attack, since the eavesdropper can run independent QKD instances with each party and reconcile two keys under full control. Existing authentication methods are analysed and classified by the underlying cryptographic primitive: symmetric schemes based on Wegman–Carter universal hashing, pre-shared and fixed keys, public-key infrastructure, two-way authentication, quantum entity/identity authentication, and zero-knowledge proofs. For each class the operating principle, advantages and limitations are determined, with emphasis on key management, scalability and trust distribution. It is established that symmetric and quantum-layer methods rely on pre-shared secrets with a quadratic growth of key material, public-key infrastructure introduces a single trust bottleneck and quantum-vulnerable primitives, while existing zero-knowledge authentication schemes are quantum and bound to the physical layer or solve network properties other than identity. A comparative analysis reveals an unresolved scientific gap: the absence of a scalable entity-authentication method that simultaneously provides non-disclosure of the secret, quantum resistance, sub-quadratic scalability and minimisation of trust assumptions. On this basis, a prospective research direction is substantiated – the construction of entity-authentication methods based on post-quantum zero-knowledge proofs operating over the classical control plane of scalable QKD networks. The requirements for such a method are formulated, and its compatibility with formal QKD security proofs is discussed.
The paper addresses entity authentication in quantum key distribution (QKD) systems as a decisive condition of their practical security. It is shown that the information-theoretic security of quantum key agreement does not eliminate the need to authenticate the communicating parties: an unauthenticated classical channel leaves the system exposed to the man-in-the-middle attack, since the eavesdropper can run independent QKD instances with each party and reconcile two keys under full control. Existing authentication methods are analysed and classified by the underlying cryptographic primitive: symmetric schemes based on Wegman–Carter universal hashing, pre-shared and fixed keys, public-key infrastructure, two-way authentication, quantum entity/identity authentication, and zero-knowledge proofs. For each class the operating principle, advantages and limitations are determined, with emphasis on key management, scalability and trust distribution. It is established that symmetric and quantum-layer methods rely on pre-shared secrets with a quadratic growth of key material, public-key infrastructure introduces a single trust bottleneck and quantum-vulnerable primitives, while existing zero-knowledge authentication schemes are quantum and bound to the physical layer or solve network properties other than identity. A comparative analysis reveals an unresolved scientific gap: the absence of a scalable entity-authentication method that simultaneously provides non-disclosure of the secret, quantum resistance, sub-quadratic scalability and minimisation of trust assumptions. On this basis, a prospective research direction is substantiated – the construction of entity-authentication methods based on post-quantum zero-knowledge proofs operating over the classical control plane of scalable QKD networks. The requirements for such a method are formulated, and its compatibility with formal QKD security proofs is discussed.
Junhong Liu, Qinfei Long, Alex Pengfei Zhao, X Zhong · 7 authors
Multi-region unit commitment with reserve sharing requires coordinated optimization across jurisdictionally distinct system operators, exposing sensitive cost curves, topology, and dispatch decisions to inference attacks. The accelerating progress of quantum computing further compounds this threat. As quantum hardware matures, current classically-encrypted data flow becomes vulnerable to retrospective decryption. To enable post-quantum-secure distributed optimization, we propose a customized Benders decomposition-based approach with the global summation structure to share aggregated cuts and variables. By exploiting this structure, we further develop a multi-layer quantum-resilient secure aggregation protocol comprising additive masking for information-theoretic content privacy, affine variable transformation hiding individual sensitive data flows, and reveal-bound lattice-based zero-knowledge proofs providing resilience against active adversaries. Simulation results show that the proposed approach achieves the mean suboptimality of 0.09%-0.22% with lightweight computational overhead, recovers up to 51% of system cost via inter-regional reserve sharing, and imposes no measurable cost-quality trade-off, whereas the noisy ADMM degrades monotonically under tightening privacy budgets and becomes structurally infeasible on combinatorially dense systems.
Traditional secret sharing techniques such as Verifiable Secret sharing (VSS) are vulnerable to quantum attacks by a Cryptographically Relevant Quantum Computer (CRQC) running Shor's algorithm. We observe that the binding a VSS needs is required only at the moment of dealing, and this binding can be made before any CRQC exists. We propose Proof in a Bottle (PiB), which decouples verifiability from long-term binding: standard Pedersen commitments provide zero-knowledge, publicly checkable consistency during a pre-quantum window, while a salted, index-bound hash of the share set, anchored to an immutable public ledger, preserves the binding established in that window into the post-quantum era. The guarantee is explicitly a commit-now, reveal-later one: it protects today's honest dealings against tomorrow's quantum adversary.
Yongqiang Du, Chen-Xun Weng, Feng Xie, Ming-Yang Li · 13 authors
Popularized by the Bitcoin cryptocurrency, blockchain technology establishes a decentralized digital framework that utilizes cryptographic and consensus protocols to secure data against unauthorized modification. Consequently, blockchain has found broad adoption across diverse fields, including finance, data management, healthcare, and digital asset governance. In the quantum computing era, a paramount objective for blockchain is to preserve its foundational advantages of cryptographic integrity and decentralized fault-tolerant resilience. In principle, quantum digital signatures and quantum Byzantine agreement protocols offer foundational security guarantees and tolerate up to one-half of malicious nodes for blockchain. However, the practical realization of such a quantum-enhanced blockchain remains a significant and multifaceted challenge. Here, we propose and experimentally demonstrate a fully operational hybrid quantum blockchain architecture built on photonic integrated circuits and deployed over commercially available classical telecommunications infrastructure. The system achieves a fault tolerance of nearly one-half, surpassing the classical limit, while reaching consensus on a timescale of seconds. A deployed food traceability application validates the practicality of the proposed architecture, achieving a throughput of approximately 500 transactions per second. This work establishes a foundation for practical quantum blockchains, enabling secure, scalable, and decentralized information processing in the emerging quantum era.
Sai Sakunthala Guddanti, Anupama Ray, Mrunal Arun Kumavat, Anil Prabhakar
This article explores the potential of Quantum Machine Learning (QML), specifically assessing a Quantum Support Vector Machine (QSVM) and a Variational Quantum Classifier (VQC) for detecting anomalies in real-world financial transaction data. While these QML methods outperform statistical methods, they fall short of cutting-edge deep learning techniques. To bridge this gap, we propose a hybrid quantum-classical ensemble framework that leverages the strengths of both domains. We demonstrate its effectiveness in detecting phishing in Ethereum transaction networks by combining complementary algorithms. The QSVM, whether used individually or in an ensemble, consistently delivered the lowest false negatives and higher recall rates, that are crucial for anomaly detection. To enhance individual models, we encoded the data using novel cascaded Quantum Random Access Coding (QRAC) schemes and compared it with the popular encoding ZZ feature map on both simulators and the IBM Heron quantum processor. For both QSVM and VQC, we consistently observed improvements (13% for QRAC-VQC and 3% for QRAC-QSVM) of QRAC over the ZZ feature map. Notably, certain QML algorithms exhibit remarkable resilience on the IBM Heron quantum processor, approaching simulator-level performance on devices with high quantum volume. This observation underscores the promise of QML despite hardware limitations.
Objectives . The aim of this work is to develop and implement a conceptual model of a quantum-secured blockchain by integrating a quantum key distribution mechanism based on the E91 protocol into a classical architecture. Methods . The vulnerabilities of classical blockchain cryptographic mechanisms to threats posed by quantum computing are considered. To create a resilient architecture, it is proposed to combine the properties of quantum entanglement with classical cryptographic methods. The E91 quantum key distribution protocol, based on quantum entanglement and the Bell inequality test (CHSH test), is used as the foundation. A new field, E91 MAC, is introduced to link blocks in the chain, calculated using the HMAC algorithm from the hash of the previous block with a key generated by the E91 protocol. The Delegated Proof of Stake (DPoS) algorithm is chosen as the consensus mechanism. The software implementation includes simulating the E91 protocol using the IBM Quantum cloud platform and the Qiskit library, as well as deploying a peer-to-peer blockchain network with a CLI interface in Python using TCP sockets. Results . A conceptual model was developed and a prototype of a quantum-secured blockchain was implemented. A functional peer-to-peer network with the DPoS consensus algorithm and a distributed voting mechanism was created. The successful simulation of the E91 protocol confirmed the possibility of generating and verifying a quantum key. The fundamental feasibility of integrating a quantum authentication mechanism (E91 MAC) into the block creation and validation process was demonstrated. Conclusion . The proposed hybrid architecture demonstrates a novel approach to blockchain security, based not only on computational complexity but also on the fundamental laws of quantum mechanics. The integration of the E91 protocol and the DPoS mechanism provides potential resilience to quantum attacks and high network energy efficiency. The software prototype confirms the practical feasibility of the concept for creating secure next-generation distributed ledgers.
As quantum computing moves to a cloud-based service model, a privacy–utility dilemma arises: effective Quantum Error Mitigation (QEM) requires circuit visibility, yet circuits and noise models are often proprietary. We propose Blind-QEM, a privacy-preserving framework that enables outsourced mitigation without revealing circuit topology. Using Zero-Knowledge Proofs (ZKPs) and a receipt-based binding mechanism anchored by QPU-signed execution logs, Blind-QEM verifies policy compliance and cryptographically links results to committed circuits. This allows Service Providers to perform global incoherent noise cancellation and readout mitigation using only verified aggregate statistics, ensuring mutual protection of user IP and SP models.
In the era of quantum computing, data sharing in the Internet of Vehicles (IoV) confronts the challenges of auditability, efficiency, and quantum security. However, existing research remains insufficient to meet the requirements of high mobility, resource constraints, and resilience against quantum attacks. In this paper, we propose a new quantum-secure auditable data sharing framework, in which we first present a quantum-resistant puncturable signature algorithm (QRPPRFS). Combining the low-noise LPN-based pseudorandom function with an optimized trapdoor generation mechanism, it achieves compact key sizes and millisecond-level signing; second, the blockchain and dual-commitment proof mechanism are integrated to ensure anonymity, transparent auditability and robustness. Finally, we rigorously demonstrate the correctness of our scheme, the EUF-CMA with puncturing of QRPPRFS, and the knowledge soundness and witness zero-knowledge of the dual-commitment proof system. Experimental evaluations show that, under the practical setting$n=256$and$q \approx 2^{23}$, the proposed scheme keeps both signing and verification latencies below 10 ms, and reduces the initial secret-key storage to only 0.22 MB. These results demonstrate that the proposed scheme achieves both enhanced security and high efficiency, outperforming existing schemes.
Swati Sachan, Dale Fickett, Richard Buchinger, Theo Miller
Recent advances in error-corrected qubits have accelerated the timeline for practical quantum computing. It poses a threat to cryptographic primitives used to secure financial systems, government infrastructure, communication networks, and DeFi (Decentralized Finance) ecosystems. This paper introduces a post-quantum secure federated DeFi framework that enables inter-bank collaboration to improve the inclusivity of individuals underserved by local lenders due to limited financial histories. Multiple banks contribute encrypted information batches to a virtual server, where lattice-based Fully Homomorphic Encryption (FHE) enables end-to-end homomorphic computation. The server fuses local data-driven probabilistic assessments, expert beliefs, and verifiable evidence generated by the NASA-IBM Prithvi Geospatial Foundation Model (GFM), in encrypted format. Decentralized technologies are employed to ensure tamper-proof evidence and auditable accountability for all encrypted data exchanges between institutions and the server. The framework is tested on agricultural lending decisions for rural borrowers in Virginia.
Jorge Garcia-Diaz, Daniel Escánez-Expósito, Pino Caballero-Gil, Jezabel Miriam Molina-Gil
Abstract Zero Knowledge Proofs based on computational hardness assumptions are fundamental primitives for secure user authentication. This paper proposes a novel Designated Verifier Zero Knowledge Proof that leverages the inherent randomness of quantum bits. Unlike traditional constructions relying on computationally intractable NP problems, the proposed protocol derives its security from the physical layer, specifically the uncertainty principle of quantum state projections in misaligned measurement bases. A rigorous formal mathematical analysis establishes the completeness, soundness and zero knowledge properties of the scheme. Furthermore, the protocol’s performance is evaluated via a quantum simulator under realistic error-prone conditions. The results demonstrate that the construction is robust against dishonest parties while remaining feasible under constrained quantum resources, offering a scalable approach for secure quantum authentication.
Decentralized Autonomous Organizations (DAOs) allow for novel collective governance. However, their reliance on conventional forms of cryptography raises fundamental security concerns, as well as paradoxes in their governance. With the emergence of fault-tolerant quantum computers threatening critical IoT-Blockchain ecosystems, which will shatter today's monetary encryption, this study proposes the first holistic, comprehensive, and conceptualization of a Quantum-Secured DAO (Q-DAO). Such entities will have their core functions organically designed around the foundational elements of quantum theory. Q-DAO design conceptualization transcends the mere addition of post-quantum cryptography and addresses the re-invention of the trustlessness paradigm. It will transform current reliance on a computational assumption to a physical guarantee of trustlessness as defined by the immutable and unassailable laws of nature. The designed system conceptualization will revolve around four pillars: The first is quantum-state governance designed tokens exploiting the no-cloning theorem towards Sybil attacks. The second focuses on a secure and private voting stratagem induced by quantum entanglement. The third introduces a hybrid onchain/quantum channel governance system designed to ensure simultaneous transparency and security of communication. Finally, the fourth emphasizes a novel quantum interference for dispute resolution that overcomes the Code is Law rigidity.
Margherita Cozzolino, Stephan Krenn, Thomas Lorünser
While QKD ensures information-theoretic security at the link level, real-world deployments depend on trusted repeaters, creating potential vulnerabilities. In this paper, we thus introduce a topology-hiding connectivity assurance protocol to enhance trust in quantum key distribution (QKD) network infrastructures. Our protocol allows network providers to jointly prove the existence of a secure connection between endpoints without revealing internal topology details. By extending graph-signature techniques to support multi-graphs and hidden endpoints, we enable zero-knowledge proofs of connectivity that ensure both soundness and topology hiding. We further discuss how our approach can certify, e.g., multiple disjoint paths, supporting multi-path QKD scenarios. This work bridges cryptographic assurance methods with the operational requirements of QKD networks, promoting verifiable and privacy-preserving inter-network connectivity.
This paper presents a novel hybrid zero-knowledge proof protocol resistant to quantum computer attacks. The protocol combines classical cryptography based on the Learning with Errors problem complexity with quantum state properties. The main objective of the protocol is to enable a prover to convince a verifier of knowledge of a secret parameter alpha without revealing its value, even against adversaries with quantum computational capabilities. A key feature of the protocol is the explicit dependence of quantum operations on the secret parameter through a cryptographic hash function modeled as a quantum random oracle. This ensures an inseparable connection between the quantum and classical phases of protocol execution. The protocol includes a mechanism for regular secret updates between interaction rounds, providing protection against adaptive attacks. Special attention is given to accounting for real physical errors of quantum devices – a difference threshold is introduced that allows for a certain level of noise and decoherence. The paper presents a formal security analysis of the protocol. The properties of honest-verifier zero-knowledge and proof of knowledge against quantum polynomial-time adversaries are proven. Security is justified through constructing a sequence of hybrid games showing that the probability of a successful attack is negligible relative to the security parameter plus the probability of physical implementation error. The protocol is of practical interest for building cryptographic systems in the context of quantum computing development.
The Fischlin transform yields non-interactive zero-knowledge proofs with straight-line extractability in the classical random oracle model. This is done by forcing a prover to generate multiple accepting transcripts through a proof-of-work mechanism. Whether the Fischlin transform is straight-line extractable against quantum adversaries has remained open due to the difficulty of reasoning about the likelihood of query transcripts in the quantum-accessible random oracle model (QROM), even when using the compressed oracle methodology. In this work, we prove that the Fischlin transform remains straight-line extractable in the QROM, via an extractor based on the compressed oracle. This establishes the post-quantum security of the Fischlin transform, providing a post-quantum straight-line extractable NIZK alternative to Pass' transform with smaller proof size. Our techniques include tail bounds for sums of independent random variables and for martingales as well as symmetrization, query amplitude and quantum union bound arguments.
Uma Girish, Greg Gluch, Shafi Goldwasser, Tal Malkin · 6 authors
Position verification schemes are interactive protocols where entities prove their physical location to others; this enables interactive proofs for statements of the form "I am at a location $L$." Although secure position verification cannot be achieved with classical protocols (even with computational assumptions), they are feasible with quantum protocols. In this paper we introduce the notion of zero-knowledge position verification, which generalizes position verification in two ways: 1. enabling entities to prove more sophisticated statements about their locations at different times (for example, "I was NOT near location $L$ at noon yesterday"). 2. maintaining privacy for any other detail about their true location besides the statement they are proving. We construct zero-knowledge position verification from standard position verification and post-quantum one-way functions. The central tool in our construction is a primitive we call position commitments, which allow entities to privately commit to their physical position in a particular moment, which is then revealed at some later time.
As quantum computing matures, characterizing its practical workloads and verifying quantum supremacy presents a significant challenge. Current benchmarking and claims rely on trust-based verification methods that lack public auditability. We propose a decentralized benchmarking framework implemented via an Ethereum smart contract to provide verifiable assurance in these claims. This framework generates classically intractable puzzles that, crucially, require absolutely no pre-computed secrets. By utilizing the blockchain as an immutable public ledger, independent observers can mathematically verify that any provided solution to the puzzle must have been computationally derived via quantum hardware rather than classically spoofed. Furthermore, we demonstrate how this verifiable benchmarking metric can be utilized as an automation trigger. As a practical example of such a trigger, we focus on the ability for blockchains to automatically switch to quantum-secure signature schemes upon the successful demonstration of cryptographic quantum supremacy. We demonstrate these principles with BloQBench, which implements the concept using integer factorization as the generated puzzle and Lamport signatures as the trigger-based effect. This approach demonstrates a novel use of distributed ledgers for quantum workload characterization, providing a transparent, automated metric for measuring quantum supremacy while managing the performance and complexity trade-offs of post-quantum technology transitions.