Blockchain Papers

Umer Nauman, Miaolei Deng, Yuhong Zhang, Sheheryar Khan

No abstract is available for this record.

Shafik Nassar, R. Ramachandran

Statistical witness indistinguishability is a relaxation of statistical zero-knowledge which guarantees that the transcript of an interactive proof reveals no information about which valid witness the prover used to generate it. In this paper we define and initiate the study of QSWI, the class of problems with quantum statistically witness indistinguishable proofs. Using inherently quantum techniques from Kobayashi (TCC 2008), we prove that any problem with an honest-verifier quantum statistically witness indistinguishable proof has a 3-message public-coin malicious-verifier quantum statistically witness indistinguishable proof. There is no known analogue of this result for classical statistical witness indistinguishability. As a corollary, our result implies SWI is contained in QSWI. Additionally, we extend the work of Bitansky et al. (STOC 2023) to show that quantum batch proofs imply quantum statistically witness indistinguishable proofs with inverse-polynomial witness indistinguishability error.

Shruti Kundu, Twinkle Gupta, Akash Sardar, Anjan Bandyopadhyay · 6 authors

Quantum computing stands poised to transform numerous fields of modern technology by offering computational capabilities beyond those of classical systems. This survey offers a detailed analysis of major fields, such as artificial intelligence and machine learning (AI/ML), blockchain, cybersecurity, and digital communication, highlighting how they are significantly transformed through advancements in quantum computing. It presents a comparative analysis of current quantum computing paradigms and architectures, and examines major quantum algorithms such as Shor’s integer factorization algorithm, Grover’s search algorithm, and hybrid quantum–classical approaches like QAOA and VQE, highlighting their implications for real-world problem solving. Significant advancements in quantum hardware are surveyed, from increasing qubit counts and improved coherence to progress in error mitigation and emerging quantum processor technologies, and their impact on near-term and long-term computing capabilities is evaluated. Finally, the current limitations of quantum computing are discussed, and forward-looking insights into future research directions are provided, outlining the path toward fully harnessing quantum power across industries.

Muskan Srivastava, Sunil Kumar Singh, Pradeep Kumar Singh

Abstract Oblivious transfer is a type of message transfer in which a sender transmits one out of many potential pieces of information to the receiver, but she has no knowledge about the actual piece of information being received by the receiver. Oblivious transfer is a deceptively simple scheme that has many possible applications such as secure multiparty computation, private set intersection, federated learning, zero-knowledge proofs, accessing sensitive data etc. Security of most classical oblivious transfer protocols is based upon the unproven assumptions about the computational complexity of certain number theoretic problems such as integer factorization. So, existing classical protocols for oblivious transfer are only computationally secure and not unconditionally secure. Although many quantum oblivious protocols have been proposed lately, they are not simple and easy to implement. In the present work we propose a quantum oblivious transfer protocol that is efficient, simple and easily implementable with the existing quantum technology.

Amandeep Singh Bhatia, Sabre Kais

Federated Learning (FL) has become increasingly popular across different sectors, offering a way for clients to work together to train a global model without sharing sensitive data. It involves multiple rounds of communication between the global model and participating clients, which introduces several challenges like high communication costs, heterogeneous client data, prolonged processing times, and increased vulnerability to privacy threats. In recent years, the convergence of federated learning and parameterized quantum circuits has sparked significant research interest, with promising implications for fields such as healthcare and finance. By enabling decentralized training of quantum models, it allows clients or institutions to collaboratively enhance model performance and outcomes while preserving data privacy. Recognizing that Fisher information can quantify the amount of information that a quantum state carries under parameter changes, thereby providing insight into its geometric and statistical properties. We intend to leverage this property to address the aforementioned challenges. In this work, we propose a Quantum Federated Learning (QFL) algorithm that makes use of the Fisher information computed on local client models, with data distributed across heterogeneous partitions. This approach identifies the critical parameters that significantly influence the quantum model's performance, ensuring they are preserved during the aggregation process. Our research assessed the effectiveness and feasibility of QFL by comparing its performance against other variants, and exploring the benefits of incorporating Fisher information in QFL settings. Experimental results on ADNI and MNIST datasets demonstrate the effectiveness of our approach in achieving better performance and robustness against the quantum federated averaging method.

Collins Izuchukwu Okafor, Love Allen Chijioke Ahakonye, Jae Min Lee, Dong‐Seong Kim

Integrating Internet of Things (IoT) networks with blockchain technology has introduced transformative potential for secure, decentralized applications. However, with expanding IoT networks and the rapid advancements in quantum computing, which can break the classical encryption mechanism employed in these networks, securing validator communications in blockchain consensus mechanisms becomes increasingly challenging. This study presents PureQuantum, a novel quantum-enhanced framework that integrates quantum key distribution (QKD) into a proof-of-authority and association (PoA 2 ) consensus mechanism. Our experimental evaluation demonstrates that PureQuantum achieves a key generation time of approximately 2.315 s (BB84) and an average error rate of 0.2493, thereby ensuring robust resistance to classical and quantum computational threats. Exploring the architecture, design, and performance of PureQuantum, this concept highlights its ability to balance scalability, energy efficiency, and quantum-resilient security. By integrating QKD into validator communication protocols, PureQuantum provides a future-proof framework capable of supporting the demands of IoT-enabled decentralized systems.

Chuhan Lu

Quantum pseudorandomness is an emerging research area. Ji, Liu, and Song defined pseudorandom states (PRSs) and pseudorandom unitaries (PRUs) as quantum analogs of pseudorandom generators and pseudorandom functions. A unitary oracle separation result between one-way functions and PRSs/PRUs, established by Kretschmer, suggests that certain quantum primitives may remain secure even if classical cryptography is compromised. This insight has spurred extensive work on quantum pseudorandomness and its applications in quantum cryptography. Many constructions of PRSs have been established under standard assumptions, yet building a secure PRU was a long-standing open problem. This dissertation aims to narrow the gap between PRSs and PRUs and presents results that go beyond PRSs. We introduce Pseudorandom State Scramblers (PRSSs), a new primitive that lies between PRSs and PRUs. A PRSS maps any pure state to a pseudorandom state, a property shared with PRUs but not with PRSs. We present a construction of PRSSs inspired by the well-known Kac’s walk, and in particular, we develop a parallel variant that significantly accelerates the mixing time, enabling an efficient construction. PRSSs support cryptographic tasks not known to be achievable from PRSs alone, including a quantum encryption scheme and a succinct quantum state commitment. Additionally, when suitable classical randomness is provided, our construction exhibits a special dispersing property not known to be satisfied by any existing construction of quantum pseudorandom primitives. Our subsequent work shows that, without asymptotically increasing the number of steps, our construction based on the parallel Kac’s walk yields PRUs with standard or even strong security. The proof builds on a recently developed technique for establishing adaptive security, known as the path-recording method. This result provides an alternative construction of PRUs and further showcases the power of this proof technique. In addition, this dissertation includes two side projects. The first revisits the Hidden Subgroup Problem over ℤn, providing a simplified analysis of a known quantum algorithm using elementary lattice tools. The second establishes a quantum analogue of a classical impossibility result for statistical non-interactive zero-knowledge arguments, showing limitations of black-box reductions under classical-query quantum adversaries.

N. Ramanjaneya Reddy, Supriya Suryadevara, K. Guru Raghavendra Reddy, R. Umamaheswari · 6 authors

Quantum computing is an evolution of classical computing, capable of solving problems that are competitive enough to break the existing cryptographic primitives upon which current blockchain systems are based. Popular schemes like RSA, ECDSA, and SHA-256 can be compromised by quantum algorithms (Shor's and Grover's), raising questions about the security and trustworthiness of blockchain-based applications in finance, healthcare, and supply chains. Many current approaches focus on isolated aspects of the blockchain, such as cryptographic primitives or key exchange, without a comprehensive strategy that can guarantee end-to-end security in the face of a quantum threat. Finally, traditional consensus mechanisms such as Proof-of-Work and Proof-of-Stake are vulnerable to Sybil attacks, centralization, and leader-selection bias. When the adversary has access to a quantum computer, these issues become significantly worse. In this paper, we present QuantumShield-BC, a modular blockchain framework incorporating post-quantum cryptographic signatures, quantum key distribution (QKD), and a novel Quantum Byzantine Fault Tolerance (Q-BFT) consensus mechanism driven by quantum random number generation (QRNG) to address these challenges. QKD: The system supports tamper-proof key exchange, quantum-resilient consensus among validator nodes, and secure transaction signing. Experimental evaluation demonstrates that QuantumShield-BC achieves low consensus latency and high throughput, while providing perfect security against simulated attacks from Shor's and Grover's algorithms. The proposed framework eradicates the Sybil attack effectiveness up to 0%, eliminates replay and MITM vulnerabilities, and achieves an average throughput of over 7,000 transactions per second with 100 validators, orders of magnitude better than classical blockchain systems. The importance of each quantum part to the system's robustness is also demonstrated using an ablation study. With its unique ability to provide a post-quantum framework for high-assurance, general-purpose, scalable, and interoperable blockchain networks resistant to quantum-inspired attacks or quantum retrieval, QuantumShield-BC is practical for deployment in critical infrastructure and digital trust ecosystems where performance and a future-proof foundation are essential.

Rafael H N Oliveira

This paper presents the Arkhe(n) framework, a comprehensive theoretical and engineer-ing architecture that unifies quantum mechanics, distributed ledger technology, molecularbiology, and consciousness studies under a single informational substrate. We extend theNew Subquantum Informational Mechanics (NMSI) by proposing a fundamental projectionequation C × R3 × Z −→ R4, where information flows from a complex phase field throughdiscrete structural nodes into observable spacetime. We introduce the Vortex of Aether asthe physical carrier of phase (C) and validate this through retrocausal engineering protocolsutilizing the Ωccd particle. We detail the implementation of a Temporal Consensus Oraclevia gRPC and etcd, and a Caffeine Motor for high-speed phase computation (< 16μs).Furthermore, we bridge biological substrates to this network via a Neural-Molecular Bridge(Swift/iOS), translating heart rate variability (HRV) into ConsciousnessPayloads, and pro-pose RNA Computing as the molecular logic gate substrate. The framework is validatedthrough a six-layer architecture spanning RNA World to Silicon GPU clusters.

Niketa Yadav, Gaurav Indra

With the emergence of quantum computing, traditional cryptographic methods used in blockchain systems face increasing risk. One such area of concern is the Layer-2 protocols zk-Rollups designed to improve scalability and privacy in platforms like Ethereum, which are heavily dependent on classical zero-knowledge proofs such as zk-SNARKs and zk-STARKs. These systems may be compromised by quantum algorithms. To address this, we propose a quantum-secure zk-Rollup model using Quantum Zero-Knowledge Proofs (QZKPs), implemented with IBM’s Qiskit simulator. The protocol uses quantum features like superposition and random basis selection to verify transactions without leaking private data. Simulation results confirm key properties: valid proofs are reliably accepted, while invalid ones are rejected. This demonstrates both the feasibility and future relevance of integrating QZKPs into blockchain systems for post-quantum security.

M Lakshmanan

Cross-border payment systems face growing complexity and urgency, driven by rapid globalization, fluctuating exchange rates, and the expansion of decentralized finance (DeFi). Simultaneously, the looming advent of quantum computing threatens to undermine traditional cryptographic methods, pressing the need for future-proof solutions. In this paper, we propose a Quantum-Safe Fuzzy Transformer framework that unifies fuzzy logic with Transformer-based sequence modeling, enhanced by post-quantum cryptographic primitives. Our approach tackles two critical challenges: handling data uncertainty and market volatility-common in cross-border transactions-through fuzzy membership functions seamlessly embedded in the self-attention mechanism, and ensuring robust security against quantum-era threats via lattice-based signatures and key exchanges. Empirical evaluations on a simulated DeFi payment network demonstrate that the proposed model maintains high transaction throughput and low latency, even under stress-test conditions reflecting extreme exchange rate fluctuations. Furthermore, the quantumsafe cryptographic layer defends settlement integrity, highlighting the practicality of post-quantum methods for realworld payment pipelines. By fusing explainable fuzzy transformations with a resilient cryptographic infrastructure, this work paves the way for an AI-driven, trust-minimized ecosystem capable of withstanding the next wave of financial and computational revolutions.

Henrique Hepp, Murilo V. G. da Silva, Leandro M. Zatesko

The complexity class of the problems that can be solved by a quantum algorithm in a non-adaptive collapse-free model is called naCQP. This class was introduced in 2016 by Aaronson et al. intended to be a slightly larger class than BQP: larger enough to include important NP-intermediate candidate problems, but likely not to include NP-complete problems. Aaronson et al. (2016) showed that there is an oracle A for which NPA ⊈ naCQPA; and Hepp et al. (2025) showed that relative to an oracle A chosen uniformly at random, (UP ∩ coUP)A ⊈ naCQPA with probability 1, being UP ∩ coUP a subclass of NP. Amongst the NP-intermediate candidate problems in naCQP is the entire class SZK, of the problems that admit a statistical zero-knowledge interactive proof system. The relation between QSZK, which is the class of the problems that admit a quantum zero-knowledge interactive proof system, and naCQP is unknown, with some believing that there is an oracle A for which QSZKA ⊈ naCQPA. A promise problem complete for QSZK is the trace distance distinguishability of mixed quantum states. We show that this problem, when restricted to pure quantum states, is in naCQP.

Serhan W. Bahar

The emergence of quantum computing presents profound challenges to existing cryptographic infrastructures, whilst the development of central bank digital currencies (CBDCs) has raised concerns regarding privacy preservation and excessive centralisation in digital payment systems. This paper proposes the Quantum-Resilient Privacy Ledger (QRPL) as an innovative token-based digital currency architecture that incorporates National Institute of Standards and Technology (NIST)-standardised post-quantum cryptography (PQC) with hash-based zero-knowledge proofs to ensure user sovereignty, scalability, and transaction confidentiality. Key contributions include adaptations of ephemeral proof chains for unlinkable transactions, a privacy-weighted Proof-of-Stake (PoS) consensus to promote equitable participation, and a novel zero-knowledge proof-based mechanism for privacy-preserving selective disclosure. QRPL aims to address critical shortcomings in prevailing CBDC designs, including risks of pervasive surveillance, with a 10-20 second block time to balance security and throughput in future monetary systems. While conceptual, empirical prototypes are planned. Future work includes prototype development to validate these models empirically.

Ankita Sharma, Pritaj Yadav

In the rapidly evolving landscape of cloud computing, ensuring secure user authentication and protection against cyber-attacks has become increasingly critical. This research proposes a novel security framework for cloud systems based on the Quantum Zero-Knowledge Proof (ZKP) technique, aiming to provide a privacy-preserving and quantum-resilient authentication mechanism. The core of the proposed model lies in leveraging photon polarization at specific quantum angles to implement secure and non-disclosive verification, effectively allowing users (provers) to prove their identity without revealing any sensitive credentials. The system's architecture integrates a Zero Knowledge Proof Engine (ZKE), which forms the backbone of the security protocol, enhancing resilience against Denial-of-Service (DoS) and Distributed Denial-of-Service (DDoS) attacks. The quantum properties of photons enable a high level of randomness and unpredictability, significantly improving the robustness of the system. A Python-based simulation environment has been developed to model the proposed engine and conduct experimental validations. Furthermore, a web-based application interface has been designed to facilitate seamless interaction between cloud users and the authentication system, demonstrating real-time threat detection and response. Experimental results, visualized through performance metrics and interface output, confirm the effectiveness and practicality of the proposed model. This approach not only enhances security but also offers a scalable and user-friendly solution for modern cloud environments, marking a significant step toward integrating quantum principles into mainstream cybersecurity infrastructures.

Nellore Kapileswar, Judy Simon

However, with the rapid development of quantum computing cracking the basic security algorithms of the current blockchain system, such as RSA and ECC, is a big threat. To tackle this critical issue, this work is aimed to develop a quantum resilient consensus scheme that combines in general purpose blockchain architectures with lattice based cryptographic primitives. This model is based on the hardness of lattice problems, which are believed to be resistant to even the attack of quantum; securing blockchain data long and immutably. Our contribution is a novel Proof of Work (PoW) and Proof of Stake (PoS) hybrid, combined with three primitives for secure identity management, digital signature and transaction validation, provided by Learning with Errors (LWE) and Ring-LWE. Quantum Resistance, Computational Complexity, Latency and Network Scalability of the proposed system is evaluated with respect to the classical methods and it is demonstrated that the proposed system is superior in all of these aspects. This marks a critical and one important step toward future proofing blockchain ecosystems as they will be forced into the quantum paradigm that will be inevitable.

Cambyse Rouzé, Daniel Stilck França, Álvaro M. Alhambra

International audience

S. Jagan, B. Girirajan, Manisha Bhimrao Mane, Hussana Johar R B · 6 authors

The convergence of quantum computing and artificial intelligence (AI) has introduced innovative opportunities to accelerate deep learning, particularly within decentralized cloud architectures. This study develops an adaptive quantum AI model leveraging hybrid quantum-classical algorithms to optimize deep learning processes such as training, inference, and resource allocation. The proposed model integrates Variational Quantum Circuits (VQCs) and Quantum Approximate Optimization Algorithms (QAOAs), which enable efficient handling of high-dimensional data and complex optimization tasks inherent in distributed environments. By addressing challenges like latency, energy efficiency, and computational overhead, the quantum AI model demonstrates significant performance gains in decentralized cloud systems.Experimental evaluations on benchmark datasets reveal a 40% reduction in training time, a 30% improvement in resource efficiency, and a 20% increase in prediction accuracy compared to classical deep learning frameworks. This study highlights the transformative potential of quantum computing in AI-driven decentralized cloud architectures, offering insights into its application for computationally intensive tasks across industries such as healthcare, finance, and logistics. Future work will focus on refining quantum hardware compatibility, developing quantum error correction methods, and exploring federated learning applications to expand the scope of quantum AI in privacy-preserving and distributed systems.

AnQi Chi, Lin Bi, Gopal Verma, Xiaoqiang Di

No abstract is available for this record.

Aditi Rai, Vijay Kumar Yadav

The major challenge in the existing communication system is maintaining the user's privacy while ensuring the pro- cess of verification and authentication. The conventional methods either jeopardize with user's privacy by linking the data or message to the source or fail to prevent false submissions because of weak authentication mechanisms. To address these issues, this paper proposes a Zero-Knowledge Proofs-based Quantum- resistant Anonymous and Authenticated Feedback System that optimizes Zero-Knowledge Succinct Non-Interactive Argument of Knowledge, shortly termed as zk-SNARKs, to enable secure, anonymous, and verifiable feedback submissions. The method presented in this research achieves strong authentication without sacrificing user privacy, which was not possible with traditional techniques like digital signatures, public-key infrastructure, and others. The system is resistant to impersonation and Sybil attacks because it uses zk-SNARKs to enable users to authenticate their permission to send feedback without disclosing their identity. Furthermore, the suggested framework is made to be postquantum secure, guaranteeing long-term resilience against sophisticated quantum attackers, since quantum computing poses a danger to traditional cryptographic techniques like RSA and ECC. Security, effectiveness, and practical viability of the system are assessed, based on which it is concluded that zk-SNARKs are a reliable and scalable basis for privacy-preserving feedback mechanisms and in various other applications like online dis- cussion forums, educational assessments. The study highlights how well zk-SNARKs succeeds in making a privacypreserving authentication system and mitigating the risk of quantum attacks.

Sultan Almuhammadi, Sarah Alghamdi

Blockchain-based public ledgers, known as cryptocurrencies, are used to build peer-to-peer digital payment systems. Cryptocurrency transactions are secured by digital signatures. However, today's public-key cryptography, which is the basis of digital signatures, is vulnerable to quantum attacks. Therefore, there is a significant risk to the 2.7 trillion dollar market capitalization of the cryptocurrency sector in the Quantum Era. In this paper, we review the current risk of quantum attacks on the blockchains of cryptocurrencies. We also discuss the migration of existing cryptocurrencies from classical to quantum-resistant blockchains and review some of the existing transition protocol algorithms. The main contribution of this work is to propose a new transition protocol algorithm that allows smooth and safe migration to post-quantum blockchains without delay. The proposed algorithm requires a soft fork of the original blockchain, which makes it more desirable than other hard-fork solutions. We also prove the soundness and completeness properties of the proposed algorithm and discuss its advantages compared to the existing ones. We conclude by highlighting our recommendations based on this study.

Marta Irene García Cid

The main motivation of this thesis is the uncertain panorama of cybersecurity risks and threats, accentuated by the arrival of the quantum computer. This type of computer is completely disruptive, since its operation is governed by quantum mechanical phenomena. The implementation of Shors algorithm in a quantum computer with relevant size and performance will allow breaking the security of the most currently used pre-quantum asymmetric algorithms. This panorama makes it necessary to research new cryptographic paradigms that are resistant to quantum threats. Thus, quantum and post-quantum cryptography emerge. Several national security agencies are recommending the immediate migration to quantum-resistant solutions of vulnerable critical cryptosystems, mainly by implementing post-quantum algorithms, some of them recently standardized. Quantum cryptography bases its security on the same physical foundations as quantum computers, being independent of the computational capacity of an adversary. The implementation of solutions based on quantum cryptography still requires greater technological maturity, development of standards and certification of devices. In addition, the infrastructures necessary for these networks are expensive and difficult to scale, in their current conception, due to the need to have trusted intermediate nodes. However, the rapid advances in this field allow to further research quantum communications networks to be a reality for daily operations where a high level of security is required. The main objective of this thesis is to investigate quantum cryptography-based solutions that go beyond quantum key distribution (QKD). The thesis has focused on proposing two novel cryptographic mechanisms ensuring that the new protocols are comparable in efficiency with pre-quantum and post-quantum algorithms. Furthermore, it has been taken into account that these protocols are implementable in current quantum communications infrastructures (QCI) to maximize the technical benefit of the investments carried out for these deployments. As a result, a quantum-assisted digital signature protocol (Q-DS) and a quantum zero-knowledge proof (QZKP) have been proposed, analyzed and implemented, which combine symmetric pre-quantum mechanisms with QKD. The proposed quantum-assisted digital signature protocol avoids the use of vulnerable pre- quantum public-key cryptosystems, using symmetric keys generated by QKD and using them with widely known NIST-approved hash functions, giving rise to a composite cryptosystem whose security against various attacks is demonstrated. For its part, the proposed quantum zero-knowledge proof allows the authentication of users in a QCI without revealing personal information during the process. The proposal of a quantum version of ZKP has been done in this thesis for the very first time, without precedent in the literature. A theoretical study as well as experimental tests have been carried out, resulting in a secure and efficient authentication mechanism. Finally, given the industrial nature of this thesis, the evolution of the political panorama regarding quantum technologies and PQC have been closely followed, including the positions of relevant security-oriented organizations and economic investments for project funding. These issues, although not technical, have influenced the design of the cryptographic protocols proposed in this thesis. RESUMEN La principal motivación de esta tesis es el panorama incierto de los riesgos y amenazas de ciberseguridad, acentuado por la llegada del ordenador cuántico. Este tipo de ordenadores son completamente disruptivos, ya que su funcionamiento se rige por fenómenos mecánico-cuánticos. La implementación del algoritmo de Shor en un ordenador cuántico con tamaño y rendimiento relevantes permitirá romper la seguridad de los algoritmos asimétricos pre-cuánticos más utilizados actualmente. Este panorama hace necesario investigar nuevos paradigmas criptográficos que sean resistentes a las amenazas cuánticas. Así, surgen la criptografía cuántica y post-cuántica. Varias agencias de seguridad nacional han recomendado la migración inmediata de los criptosistemas críticos vulnerables a soluciones "quantum-resistant", principalmente mediante la implementación de algoritmos post-cuánticos, algunos de ellos recientemente estandarizados. La criptografía cuántica basa su seguridad en los mismos fundamentos físicos que los ordenadores cuánticos, siendo independiente de la capacidad computacional de un adversario. La implementación de soluciones basadas en criptografía cuántica aún requiere de mayor madurez tecnológica, desarrollo de estándares y certificación de dispositivos. Además, las infraestructuras necesarias para estas redes son costosas y difíciles de escalar, en su concepción actual, debido a la necesidad de contar con nodos intermedios de confianza. Sin embargo, los rápidos avances en este campo permiten que la investigación de las redes de comunicaciones cuánticas se vaya convirtiendo en una realidad para las operaciones diarias donde se requiere un alto nivel de seguridad. El objetivo principal de esta tesis es investigar soluciones basadas en criptografía cuántica que vayan más allá de la distribución de claves cuánticas (QKD). La tesis se ha centrado en proponer dos mecanismos criptográficos novedosos asegurando que los nuevos protocolos sean comparables en eficiencia con algoritmos pre-cuánticos y post-cuánticos. Además, se ha tenido en cuenta que estos protocolos sean implementables en las actuales infraestructuras de comunicaciones cuánticas (QCI) para maximizar el beneficio técnico de las inversiones realizadas para estos despliegues. Como resultado, se han propuesto, analizado e implementado un protocolo de firma digital asistido por claves cuánticas (Q-DS) y una prueba de conocimiento cero cuántica (QZKP), que combinan mecanismos pre-cuánticos simétricos con QKD. El protocolo de firma digital cuántica propuesto evita el uso de criptosistemas de clave pública pre-cuánticos vulnerables, utilizando claves simétricas generadas por QKD y utilizándolas con funciones hash ampliamente conocidas aprobadas por el NIST, dando lugar a un criptosistema compuesto cuya seguridad frente a diversos ataques se demuestra. Por su parte, la QZKP propuesta permite la autenticación de usuarios en una QCI sin revelar información personal durante el proceso. La propuesta de una versión cuántica de ZKP se ha realizado en esta tesis por primera vez, sin precedentes en la literatura. Se ha realizado un estudio teórico así como pruebas experimentales, dando como resultado un mecanismo de autenticación seguro y eficiente. Finalmente, dada la naturaleza industrial de esta tesis, se ha seguido de cerca la evolución del panorama político en relación con las tecnologías cuánticas y PQC, incluyendo las posiciones de las organizaciones relevantes en materia de seguridad y las inversiones económicas para la financiación de proyectos. Estas cuestiones, aunque no técnicas, han influido en el diseño de los protocolos criptográficos propuestos en esta tesis.

Huifang Yu, Ming‐Hao Huang

To solve the privacy leakage and identity island problems in cross-chain interaction, we propose an anti-quantum cross-chain identity authentication approach based on dynamic group signature (DGS-AQCCIDAA) for smart education. The relay-based cross-chain model promotes interconnection in heterogeneous consortium blockchains. DGS is used as the endorsement strategy for cross-chain identity authentication. Our approach can ensure quantum security under the learning with error (LWE) and inhomogeneous small integer solution (ISIS) assumptions, and it uses non-interactive zero-knowledge proof (NIZKP) to protect user identity privacy. Our scheme has low calculation overhead and provides anonymous cross-chain identity authentication in the smart education system.

Arya Wicaksana

No abstract is available for this record.

Marija Mikić, Mihajlo Srbakoski, Strahinja Praska

The integration of privacy-preserving transactions into public blockchains such as Ethereum remains a major challenge. The Stealth Address Protocol (SAP) provides recipient anonymity by generating unlinkable stealth addresses. Existing SAPs, such as the Dual-Key Stealth Address Protocol and the Curvy Protocol, have shown significant improvements in efficiency, but remain vulnerable to quantum attacks. Post-quantum SAPs based on lattice-based cryptography, such as the Module-LWE SAP, on the other hand, offer quantum resistance while achieving better performance. In this paper, we present a novel hybrid SAP that combines the Curvy protocol with the computational advantages of the Module-LWE technique while remaining Ethereum-friendly. In contrast to full post-quantum solutions, our approach does not provide quantum security, but achieves a significant speedup in scanning the ephemeral public key registry, about three times faster than the Curvy protocol. We present a detailed cryptographic construction of our protocol and compare its performance with existing solutions. Our results prove that this hybrid approach is the most efficient Ethereum-compatible SAP to date.