Blockchain Papers

P. Naveen, S. Rajalakshmi, J. S. Abhirami, V. Vaissnave · 6 authors

No abstract is available for this record.

Meenal R Kale, Yousef A. Baker El–Ebiary, L. Sathiya, Vijay Kumar Burugari · 7 authors

Quantum computing is progressing at a fast rate and there is a real threat that classical cryptographic methods can be compromised and therefore impact the security of blockchain networks. All of the ways used to secure blockchain like Rivest–Shamir–Adleman (RSA), Elliptic Curve Cryptography (ECC) and Secure Hash Algorithm 256-bit (SHA256) are the characteristic of the traditional cryptographic techniques vulnerable to attack by quantum algorithms: Shor’s and Grover’s algorithms: can efficiently break asymmetric encryption and speed up brute force attacks. Because of this vulnerability, there exists a need to develop an advance quantum resilient blockchain framework to protect the decentralized ledgers from the future threats of the quantum. This research proposes Post-Quantum Cryptography (PQC), Quantum Key Distribution (QKD) and Quantum Random Number Generation (QRNG) as a formidable architectural integration, to fortify security of blockchain. Classical encryption is replaced with PQC, QKD with secure key exchange by detecting eavesdropping, and QRNG with improving cryptographic randomness to remove the predictable key vulnerability. Only with a small loss of transaction efficiency, we increase transaction encryption accuracy, key exchange security, and resistance to quantum attacks. In this quantum enhanced blockchain design, the idea is to preserve the decentralization, transparency and security and at the same time overcome the future quantum threat. By going through rigorous analysis and comparative evaluation, we demonstrate that the approach saves blockchain networks from the emerging quantum risks to make sure that the decentralized finance, smart contracts and cross chain transactions.

Patxi Juaristi, Isaac Agudo, Rubén Rı́os, Laura Ricci

No abstract is available for this record.

M. Albrecht, Kamil Doruk Gür

No abstract is available for this record.

Bora Buğra Sezer, Sedat Akleylek

No abstract is available for this record.

Xinxin Fan, Teik Guan Tan, Nicholas Ho, Shi Hong Choy

No abstract is available for this record.

Sunil Prajapat, Garima Thakur, Pankaj Kumar, Ashok Kumar Das · 5 authors

No abstract is available for this record.

Adeshina Akin Ajayi, Igba Emmanuel, Adesola Dorcas Soyele, Joy Onma Enyejo

This paper explores the integration of quantum cryptography and blockchain technology to address two pressing challenges: securing financial transactions in Central Bank Digital Currencies (CBDCs) and combating the spread of misinformation during U.S. elections through decentralized social media platforms. As quantum computing advances, traditional encryption methods may become obsolete, posing significant risks to digital financial systems. Quantum cryptography, with its quantum-resistant algorithms, offers enhanced protection for CBDC transactions, ensuring long-term security and privacy. Simultaneously, blockchain-based social media platforms provide a decentralized structure that can prevent the dissemination of false information by ensuring transparency and authenticity through cryptographic verification and consensus mechanisms. These platforms also facilitate decentralized identity management, empowering users to verify content without relying on centralized authorities. By combining quantum cryptography’s secure framework with blockchain’s decentralized transparency, this dual approach creates a more secure digital ecosystem that not only safeguards financial transactions but also strengthens democratic processes. The paper further addresses the regulatory and technical challenges associated with implementing these technologies and their potential to shape a more secure, transparent, and accountable future.

François Le Gall, Yupan Liu, Harumichi Nishimura, Qisheng Wang

We introduce two models of space-bounded quantum interactive proof systems, QIPL and QIP_{U}L. The QIP_{U}L model, a space-bounded variant of quantum interactive proofs (QIP) introduced by Watrous (CC 2003) and Kitaev and Watrous (STOC 2000), restricts verifier actions to unitary circuits. In contrast, QIPL allows logarithmically many pinching intermediate measurements per verifier action, making it the weakest model that encompasses the classical model of Condon and Ladner (JCSS 1995). We characterize the computational power of QIPL and QIP_{U}L. When the message number m is polynomially bounded, QIP_{U}L ⊊ QIPL unless P = NP: - QIPL^HC, a subclass of QIPL defined by a high-concentration condition on yes instances, exactly characterizes NP. - QIP_{U}L is contained in P and contains SAC¹ ∪ BQL, where SAC¹ denotes problems solvable by classical logarithmic-depth, semi-unbounded fan-in circuits. However, this distinction vanishes when m is constant. Our results further indicate that (pinching) intermediate measurements uniquely impact space-bounded quantum interactive proofs, unlike in space-bounded quantum computation, where BQL = BQ_{U}L. We also introduce space-bounded unitary quantum statistical zero-knowledge (QSZK_{U}L), a specific form of QIP_{U}L proof systems with statistical zero-knowledge against any verifier. This class is a space-bounded variant of quantum statistical zero-knowledge (QSZK) defined by Watrous (SICOMP 2009). We prove that QSZK_{U}L = BQL, implying that the statistical zero-knowledge property negates the computational advantage typically gained from the interaction.

Amandeep Singh Bhatia, David E. Bernal

Abstract The healthcare industry frequently handles sensitive and proprietary data, and due to strict privacy regulations, it is often reluctant to share it directly. In today’s context, Federated Learning (FL) stands out as a crucial remedy, facilitating the rapid advancement of distributed machine learning while effectively managing critical concerns regarding data privacy and governance. The fusion of federated learning and quantum computing represents a groundbreaking interdisciplinary approach with immense potential to revolutionize various industries, from healthcare to finance. In this work, we propose a federated learning framework based on quantum tensor networks (QTNs) that takes advantage of the principles of many-body quantum physics. Currently, there are no known classical tensor networks (TNs) implemented in federated settings. Furthermore, we investigated the effectiveness and feasibility of the proposed framework by conducting a differential privacy analysis to ensure the security of sensitive data across healthcare institutions. Experiments on popular medical image datasets show that the federated quantum tensor network (FedQTNs) model achieved a mean receiver-operator characteristic area under the curve of 91%–98%, outperforming several state-of-the-art federated learning methods. Moreover, QTN models require fewer parameters in FL settings compared to traditional classical models, which often suffer from over-parameterization. This reduction in parameters not only improves the efficiency of the communication process but also significantly decreases data consumption during training. As a result, QTN models facilitate a more effective and resource-efficient approach to training in decentralized environments with limited communication bandwidth. The FedQTN models demonstrate a smaller performance drop even when using strong differential privacy settings, maintaining higher accuracy compared to classical models under similar privacy constraints. Experimental results demonstrate that the quantum federated global model, consisting of highly entangled TN structures, showed better generalization and robustness and achieved higher testing accuracy, surpassing the performance of locally trained clients under unbalanced data distributions among healthcare institutions.

Abdullah Umar, Deepak Kumar

This paper presents a security analysis of blockchain networks with Proof-of-Stake (PoS) consensus mechanisms focusing on mitigating quantum attacks. With the advent of quantum computing, traditional cryptographic algorithms used in blockchain are at risk of being compromised, posing significant vulnerabilities to the integrity, confidentiality, and availability of blockchain systems. We explore the specific threats posed by quantum computing advancements, such as Shor’s algorithm and Grover’s algorithm, which can potentially break public key cryptography and weaken hash functions respectively. In response to these threats, we propose the implementation of quantum-resistant cryptographic solutions to safeguard blockchain networks. Our proposed solutions include the use of Keccak-based cryptographic algorithms, renowned for their robustness and efficiency in resisting quantum attacks. We detail the integration of these algorithms into blockchain platforms, ensuring that the core processes of stake verification, transaction signing, and block validation are secure. Additionally, we design and evaluate the effectiveness of the quantum-resistant Proof-of-Stake (PoS) consensus mechanism which leverages Keccak for hashing and Winternitz One-Time Signature (WOTS) for digital signatures. Through this integration, we aim to strengthen blockchain networks against the computational capabilities of future quantum computers, thus preserving the security and trustworthiness of blockchain systems.

Tao Shang

No abstract is available for this record.

Sohrab Ganjian, Connor Paddock, Anne Broadbent

Cloud computing allows clients with limited computational resources to offload computations to more powerful remote servers. In this paradigm, homomorphic encryption (HE) schemes enable a server to run any computation on a client's encrypted data. These schemes are widely used in cloud computing protocols such as delegated computing, two-party secure computation, and zero-knowledge proofs. Quantum homomorphic encryption (QHE) aims to achieve the objectives of HE with quantum data and quantum circuits, enabling cloud quantum servers to compute on encrypted quantum data uploaded by clients. In this work, we consider a scenario where a client has access to a quantum “encryption/decryption device”, which allows the encryption, transmission, reception, and decryption of quantum states, but not universal quantum computation. In this setting, we provide a proof-of-concept software simulation of quantum homomorphic encryption. Our code implements the “EPR scheme” of Broadbent and Jeffery, which allows for the execution of universal quantum circuits by the server at the cost of requiring shared EPR pairs between the client and server. Our implementation explores the near-term viability of the EPR scheme. Perhaps unsurprisingly, our experiments indicate that the additional cost of homomorphic circuit evaluation is minor in comparison to the simulation cost of the quantum operations. Our simulation toolkit is implemented in Python and is open-source.

Zixian Li, Wenjie Liu, Bing-Mei Su

Private set intersection (PSI) has important application value, however, current quantum PSI protocols are either unsuitable for multi-party scenarios or inefficient. Recently, Imran (arXiv: 2303.17196v3 , 2023) proposed two quantum secure multi-party greatest common divisor (GCD) protocols that can be used for PSI, but with the downside of information leakage and resource consumption. In this paper, we propose a novel quantum secure multi-party GCD protocol that has higher security and lower complexity. To hide privacy, each party randomly selects a coefficient within a range determined by his input integer, and with the assistance of a semi-honest third party TP, all parties secretly calculate the linear combination of their inputs under these coefficients. Once enough linear combinations are collected, TP calculates the GCD of these combinations, which is equal to the GCD of all input integers. To verify the honesty of participants, a quantum zero-knowledge proof sub-protocol is designed. Analysis shows that our GCD protocol is correct and has security against malicious attacks. Moreover, its complexity is polynomial level and lower than Imran’s. Furthermore, we demonstrate the scalability of our GCD protocol in private set operations, such as private set intersection, private set intersection cardinality, private multi-set intersection, etc.

Fariza Sabrina, Shaleeza Sohail, Umair Ullah Tariq

The Internet of Medical Things (IoMT) has significantly enhanced the healthcare system by enabling advanced patient monitoring, data analytics, and remote interactions. Given that IoMT devices generate vast amounts of sensitive data, robust privacy mechanisms are essential. This privacy requirement is critical for IoMT as, generally, these devices are very resource-constrained with limited storage, computation, and communication capabilities. Blockchain technology, with its decentralisation, transparency, and immutability, offers a promising solution for improving IoMT data security and privacy. However, the recent emergence of quantum computing necessitates developing measures to maintain the security and integrity of these data against emerging quantum threats. This work addresses the current gap of a comprehensive review and analysis of the research efforts to secure IoMT data using blockchain in the quantum era. We discuss the importance of blockchain for IoMT privacy and analyse the impact of quantum computing on blockchain to justify the need for these works. We also provide a comprehensive review of the existing literature on quantum-resistant techniques for effective blockchain solutions in IoMT applications. From our detailed review, we present challenges and future opportunities for blockchain technology in this domain.

Engin Zeydan, Luis Blanco, Josep Mangues‐Bafalluy, Abdullah Aydeger · 8 authors

As evolving digital ecosystems become increasingly interconnected and reliant on digital transactions, secure, private and user-centric identity solutions are garnering more spotlight than ever before. In this paper, we propose an innovative architecture that integrates quantum key distribution (QKD) with blockchain-based self-sovereign identity (SSI) systems for secure key distribution and network/user management for mobile networks with advanced 6G network capabilities. The proposed approach leverages the advanced security guarantes of QKD to ensure the confidentiality and integrity of communications and uses the decentralized and immutable nature of blockchain technology to give individuals/organizations control over their digital identities in mobile environments. We then go on to expound on the foundations of architectural components and discuss its implications for various telecom specific services and applications. Finally, we present challenges and future directions to provide quantum communication support against future digital threats and a decentralized framework for identity management with the global pursuit of more privacy-friendly and usercentric digital services, and offer comparisons with traditional approaches.

Poulami Das, Andreas Erwig, Michaël Meyer, Patrick Struck

Cryptocurrency networks crucially rely on digital signature schemes, which are used as an authentication mechanism for transactions. Unfortunately, most major cryptocurrencies today, including Bit-coin and Ethereum, employ signature schemes that are susceptible to quantum adversaries, i.e., an adversary with access to a quantum computer can forge signatures and thereby spend coins of honest users. In cryptocurrency networks, signature schemes are typically not executed in isolation, but within a so-called cryptographic wallet. In order to achieve security against quantum adversaries, the signature scheme and the cryptographic wallet must withstand quantum attacks.

Mingshu Cong, Tsz Hon Yuen, Siu Ming Yiu

Matrix multiplication is a common operation in applications like machine learning and data analytics. To demonstrate the correctness of such an operation in a privacy-preserving manner, we propose zkMatrix, a zero-knowledge proof for the multiplication of committed matrices. Among the succinct non-interactive zero-knowledge protocols that have an O(log n) transcript size and O(log n) verifier time, zkMatrix stands out as the first to achieve O(n2) prover time and O(n2) RAM usage for multiplying two n X n matrices. Significantly, zkMatrix distinguishes itself as the first zk-SNARK protocol specifically designed for matrix multiplication. By batching multiple proofs together, each additional matrix multiplication only necessitates O(n) group operations in prover time.

Xinhao Zheng

In recent years, blockchain technology has developed rapidly and has been widely used in medical, financial, energy and other fields. However, in the process of practical application, each blockchain is a small independent ecosystem, with all transactions and operations limited to the chain, resulting in a large number of mutually heterogeneous to independent blockchains. It presents challenges for cross-chain interactions, cross-organization data sharing, and cross-blockchain expansion, and hinders the wider application of blockchain technology. In addition, the traditional digital signature method based on elliptic curve cipher faces the threat of being cracked by quantum computing attacks. To solve the aforementioned problems, this paper proposed a blockchain smart contract technique based on quantum computing attack resistance(BSCTQCAT). The technique first introduces the digital signature of the lattice cipher into the blockchain to resist the quantum search algorithm attack. Then, based on the smart contract authentication scheme, the nodes on multiple heterogeneous chains are organized into an identity agent layer P2P network, through which transactions on the chain will establish a credible identity management and message authentication mechanism between different chains, solving the current problem that each chain is difficult to communicate with each other. In this paper, the performance of the algorithm is evaluated by simulating the Bitcoin transaction scenario and analyzing the experimental data.

Jalel Ktari, Tarek Frikha, Monia Hamdi, Nesrine Affes · 5 authors

Introduction: Blockchain technology has revolutionized data management and transaction recording, extending its application beyond cryptocurrencies to various sectors, including Central Bank Digital Currencies (CBDCs) Methods: This distributed ledger technology offers a transparent, immutable, and secure transaction platform, reducing the risk of data tampering and increasing resistance to attacks. However, challenges such as performance, scalability, and security continue to exist; these challenges are particularly concerning consensus mechanisms like Proof of Work (PoW). Field-Programmable Gate Arrays (FPGAs) present a promising solution to enhance the efficiency and security of blockchain consensus mechanisms. Results: This study explores the implementation of blockchain in embedded systems using FPGAs and discusses the post-quantum cryptographic algorithms to ensure long-term protection. Conclusion: The research highlights the potential of FPGA-based implementations to revolutionize blockchain applications, emphasizing the need for continuous adaptation and vigilance to address evolving security threats, particularly those posed by quantum computing.

S. Sabari, N. V. Keerthana

This project focuses on Zero-Knowledge Proofs (ZKPs), a groundbreaking cryptographic technique reshaping data authentication while preserving maximum confidentiality.ZKPs enable the verification of truthfulness in statements without disclosing associated data, ensuring the utmost protection of sensitive information.With applications spanning various domains, including secure authentication protocols, privacy-preserving transactions in decentralized systems like blockchain, and confidential data verification across digital interactions, ZKPs offer versatile solutions for secure communications.The project aims to safeguard sensitive business information during outsourcing service processes.The implementation of ZKPs intends to establish a secure communication framework that fosters trust among stakeholders without compromising sensitive details, ensuring enhanced confidentiality in outsourced operations.At its core, ZKPs empower a prover to convince a verifier of a statement's validity without revealing underlying data, establishing an unmatched level of security and privacy.This concept shields against unauthorized access and data breaches, fostering trust between entities without the exchange of sensitive details.The versatility of ZKPs extends beyond authentication, influencing secure voting systems, safeguarding digital identities, and facilitating confidential transactions while upholding user privacy.

Mandeep Kumar, Bhaskar Mondal

No abstract is available for this record.

Chandra Sekhar Oleti

The exponential advancement of quantum computing poses unprecedented threats to conventional cryptographic systems employed in banking infrastructure. This paper presents a comprehensive quantum-enhanced cryptographic framework that integrates post-quantum algorithms with distributed ledger technologies to establish resilient financial security systems. Through systematic analysis of lattice-based cryptography, hash-based signatures, and multivariate cryptographic schemes, this research demonstrates significant improvements in computational security while maintaining operational efficiency. The proposed framework achieves 99.7% security resilience against quantum attacks while reducing transaction processing overhead by 23% compared to traditional RSA-based systems. Experimental validation across simulated banking environments reveals enhanced performance metrics in key generation, digital signatures, and secure communication protocols. The integration of quantum-resistant algorithms with blockchain-based consensus mechanisms provides a robust foundation for future-proof banking security architectures.

Nday Kabulo Sinai, Hoh Peter In

Abstract Popular Secp256k1 and Schnorr algorithms offer strong security in current Blockchains. However, they are vulnerable to quantum attacks. To solve this problem, several quantum-resistant algorithms have been proposed. However, the performance evaluations and tangible analyses of these algorithms on current Blockchains have not been studied yet. In this context, a performance analysis of quantum-resistant algorithms on a Blockchain can provide valuable insight into the efficiency of quantum-resistant algorithms in real-world scenarios. To address this need, we prototyped and analyzed a quantum-resistant Blockchain using the Falcon algorithm. Falcon is selected because it provides smaller signature and key size compared to Crystals-Dilithium and Sphincs+. We then measured in real-time the key size, transaction signature size, and transaction verification time. The paper also discusses the potential scalability limitations of the proposed quantum-resistant Blockchain and suggests an approach to select quantum-resistant algorithms based on different Blockchain use cases. Our approach and benchmark results have implications for the future development and adoption of quantum-resistant Blockchains.