The round complexity of interactive proof systems is a key question of practical and theoretical relevance in complexity theory and cryptography. Moreover, results such as QIP = QIP(3) (STOC'00) show that quantum resources significantly help in such a task. In this work, we initiate the study of round compression of protocols in the bounded quantum storage model (BQSM). In this model, the malicious parties have a bounded quantum memory and they cannot store the all the qubits that are transmitted in the protocol. Our main results in this setting are the following: 1. There is a non-interactive (statistical) witness indistinguishable proof for any language in NP (and even QMA) in BQSM in the plain model. We notice that in this protocol, only the memory of the verifier is bounded. 2. Any classical proof system can be compressed in a two-message quantum proof system in BQSM. Moreover, if the original proof system is zero-knowledge, the quantum protocol is zero-knowledge too. In this result, we assume that the prover has bounded memory. Finally, we give evidence towards the âtightnessâ of our results. First, we show that NIZK in the plain model against BQS adversaries is unlikely with standard techniques. Second, we prove that without the BQS model there is no 2âmessage zero-knowledge quantum interactive proof, even under computational assumptions.
Emerging cryptographic systems such as Fully Homomorphic Encryption (FHE) and Zero-Knowledge Proofs (ZKP) are computation- and data-intensive. FHE and ZKP implementations in software and hardware largely rely on the von Neumann architecture, where a significant amount of energy is lost on data movements. A promising computing paradigm is computing in memory (CIM) which enables computations to occur directly within memory thereby reducing data movements and energy consumption. However, efficiently performing large integer multiplications - critical in FHE and ZKP - is an open question, as existing CIM methods are limited to small operand sizes. In this work, we address this question by exploring advanced algorithmic approaches for large integer multiplication, identifying the Karatsuba algorithm as the most effective for CIM applications. Thereafter, we design the first Karatsuba multiplier for resistive CIM crossbars. Our multiplier uses a three-stage pipeline to enhance throughput and, additionally, balances memory endurance with efficient array sizes. Compared to existing CIM multiplication methods, when scaled up to the bit widths required in ZKP and FHE, our design achieves up to 916x in throughput and 281x in area-time product improvements.
In distributed computing, data trading mechanisms are essential for ensuring the sharing of data across multiple computing nodes. Nevertheless, they currently encounter considerable obstacles, including low accuracy in matching trading parties, ensuring fairness in transactions, and safeguarding data privacy throughout the trading process. To address these issues, we put forward a data trading security scheme based on zero-knowledge proofs and smart contracts. In the phase of preparing the security parameters, the objective is to reduce the complexity of generating non-interactive zero-knowledge proofs and to enhance the efficiency of data trading. In the pre-trading phase, we come up with attribute atomic matching smart contracts that are based on precise data property alignment. The goal is to get trading parties to match data attributes in a very specific way. During the trading execution phase, we use lightweight cryptographic algorithms based on Elliptic Curve Cryptography (ECC) and non-interactive zero-knowledge proofs to encrypt trading data twice and make attribute proof contracts. This keeps the data safe and private. The results of experiments conducted on the Ethereum platform in an industrial Internet of Things (IoT) scenario demonstrate that our scheme maintains stable and low-cost consumption while ensuring accuracy in matching and privacy protection. Especially in battery industrial manufacturing, the application of distributed computing is in huge demand and essential to maintaining a healthier technology integration among various systems and technological nodes to perform the better management of energy cells within the battery management system.
Rahat Pervez, Afsana Alam Nova, Mir Nafiul Nagib, S. Sultana ¡ 6 authors
Cryptocurrency markets are characterized by high volatility and nonlinear dynamics, making accurate analysis and forecasting challenging. This study proposes a novel quantum computing-based model, CryptoQNet, to address these challenges by leveraging Quantum Feature Maps, Variational Quantum Circuits, and Quantum Recurrent Neural Networks. CryptoQNet outperforms classical models such as LSTMs and GRUs, achieving a Mean Absolute Error (MAE) of 0.021 and Root Mean Squared Error (RMSE) of 0.028 for Bitcoin price predictions, compared to 0.038 and 0.045 by LSTMs. For Ethereum, the model achieved an MAE of 0.018 and RMSE of 0.025, demonstrating its robustness in modeling complex market trends. Additionally, CryptoQNet significantly reduced Mean Absolute Percentage Error (MAPE) for volatility prediction, achieving 3.2% for Bitcoin and 3.6% for Ethereum, compared to over 5% by classical models. The model also provides enhanced interpretability, identifying price and volume as key factors influencing market trends. While training time is higher due to quantum computations, inference efficiency and accuracy make CryptoQNet a promising tool for financial forecasting. This study highlights the transformative potential of quantum computing in financial market analysis and offers directions for future research in hybrid quantum-classical approaches.
The rise of quantum computing poses a serious threat to the cryptographic backbone of decentralized systems like Ethereum's Plasma chains, which rely on classical cryptography. This paper introduces a novel approach, integrating post-quantum cryptography (PQC) with hybrid frameworks that blend quantum-resistant algorithms with traditional cryptographic techniques. This hybrid approach ensures strong quantum-resistant security while maintaining Plasma's scalability, performance, and compatibility with Ethereum's ecosystem. This study focuses on critical plasma components like state transitions, fraud proofs, and exit strategies, that are most vulnerable to quantum attacks, proposing hybrid cryptography for low risk, high frequency transactions, while leveraging post-quantum solutions like Kyber and NTRU for securing long-term commitments and high-risk processes. By establishing clear decision criteria to determine when hybrid cryptography should take precedence over pure PQC, based on factors such as computational efficiency, security demands, and system interoperability. The insights set a new standard for Plasma's quantum resilience, ensuring it stays secure and adaptable as quantum computing evolves, paving path for decentralized finance to thrive in the face of quantum threats.
We propose a scalable quantum architectures which can improve operation of Blockchain systems. We focus on permissioned blockchains with consensus derived from Practical Byzantine Fault Tolerance (PBFT). We propose multipartite entanglement quantum architectures that can perform PBFT. Further we develop quantum systems and algorithms that can support Proof of Stake (PoS) voting as well as voter election and voting in delegated Proof of Stake systems. Validating nodes within a cluster hold qubits entangled in multipartite structure. Due to maximally connected entanglement they jointly perform voting and calculate voting results. We propose algorithms that can track voter's behavior and detect collusion and voting centralization problem.
Recently, the practical applications of advanced cryptographic protocols, such as Multi-Party Computation (MPC), Fully Homomorphic Encryption (FHE), and Zero Knowledge Proofs (ZKP), have spurred the development of a series of new symmetric encryption primitives. These novel symmetric encryption primitives, referred to as Arithmetization-Oriented (AO) ciphers, aim to minimize the number of field multiplications in large finite fields, including đ˝2n or đ˝p. In order to evaluate the algebraic degrees of AO ciphers over đ˝2n, the general monomial prediction technique was proposed by Cui et al. at ASIACRYPT 2022. However, when using their searching tool to evaluate the algebraic degrees of AO ciphers with complex affine layers, the efficiency is low, preventing solutions within a predetermined timeframe. In this study, we extend the propagation rules of monomials for field-based operations and present an automatic searching tool based on Mixed Integer Linear Programming (MILP) and Boolean Satisfiability (SAT) Problem for evaluating the upper bound of the algebraic degrees. Moreover, to accurately calculate the algebraic degrees of monomials in the SAT model, we improve the sequence encoding method, enabling it to accurately determine whether the monomials of degree d exist in the output. We apply our new searching tool to various AO ciphers, including Chaghri, MiMC, and Ciminion. For Chaghri, we compare our results with the Coefficient Grouping technique proposed by Liu et al. at EUROCRYPT 2023, and our results yield tighter upper bounds compared to Liu et al.âs findings. Additionally, we evaluate the algebraic degrees of Chaghri and MiMC with arbitrary complex affine layers and obtain tighter bounds compared to the results from Liu et al. at CRYPTO 2023. Regarding Ciminion, we have observed that starting from the 4-th round, the upper bound on the algebraic degrees for each round actually 1 degree lower than the previous bound. Our searching tool enables a more precise evaluation of the algebraic degrees of AO ciphers, contributing to a deeper understanding of the design and analysis of such primitives.
The internet is evolvingâfrom sharing information (Web 1.0) to exchanging value (Web 2.0). Blockchain technology, also known as distributed ledger technology, is powering this transformation. By using a network of computers, cryptography and irreversible records, blockchain enables secure and transparent transactions without intermediaries. This unlocks the potential to streamline the transfer of digital assets like money, intellectual property, and more, revolutionising industries. Blockchain&s;s rapid rise is fuelled by global investments and a surge in government and corporate innovation. It offers the promise of digitised records, reduced costs, real-time solutions and even greater efficiency and transparency in governance. However, challenges exist alongside these benefits, including the need for regulatory frameworks and adaptation to the potential threats posed by quantum computing. The development of quantum-resistant blockchain solutions will be crucial to ensure security as this technology matures. Like all powerful technologies, blockchain&s;s impact depends on how it&s;s implementedâoffering both transformation and potential for disruption.
Joseph T. Yun, Eli Lifton, Eunseo Lee, Y. M. Yun ¡ 11 authors
The rapid advancements in quantum computing present significant threats to existing encryption standards and internet security. Simultaneously, the advent of Web 3.0 marks a transformative era in internet history, emphasizing enhanced data security, decentralization, and user ownership. This white paper introduces the W3ID, an abbreviation of Web3 standard meeting universal digital ID, which is a Universal Digital Identity (UDI) model designed to meet Web3 standards while addressing vulnerabilities posed by quantum computing. W3ID innovatively generates secure Digital Object Identifiers (DOIs) tailored for the decentralized Web 3.0 ecosystem. Additionally, W3ID employs a dual-key system for secure authentication, enhancing both public and private verification mechanisms. To further enhance encryption strength and authentication integrity in the quantum computing era, W3ID incorporates an advanced security mechanism. By requiring quadruple application of SHA-256, with consecutive matches for validation, the system expands the number of possibilities to 256^4, which is approximately 4.3 billion times the current SHA-256 capacity. This dramatic increase in computational complexity ensures that even advanced quantum computing systems would face significant challenges in executing brute-force attacks. W3ID redefines digital identity standards for Web 3.0 and the quantum computing era, setting a new benchmark for security, scalability, and decentralization in the global digital twin ecosystem.
Bit commitment is a fundamental cryptographic primitive and a cornerstone for numerous two-party cryptographic protocols, including zero-knowledge proofs. However, it has been proven that unconditionally secure bit commitment, both classical and quantum, is impossible. In this work, we demonstrate that imposing a restriction on the committing party to perform only separable operations enables secure quantum bit commitment schemes. Specifically, we prove that in any perfectly hiding bit commitment protocol, an honestly-committing party limited to separable operations will be detected with high probability if they attempt to alter their commitment. To illustrate our findings, we present an example protocol.
Non-interactive zero-knowledge (NIZK) proof systems are a cornerstone of modern cryptography, but their security has received little attention in the quantum settings. Motivated by improving our understanding of this fundamental primitive against quantum adversaries, we propose a new definition of security against quantum adversary. Specifically, we define the notion of quantum simulation soundness (SS-NIZK), that allows the adversary to access the simulator in superposition. We show a separation between post-quantum and quantum security of SS-NIZK, and prove that Sahaiâs construction for SS-NIZK (in the CRS model) can be made quantumly-simulation-sound. As an immediate application of our new notion, we prove the security of the Naor-Yung paradigm in the quantum settings, with respect to a strong quantum IND-CCA security notion. This provides the quantum analogue of the classical dual key approach to prove the security of encryption schemes. Along the way, we introduce a new notion of quantum-query advantage functions, which may be used as a general framework to show classical/quantum separation for other cryptographic primitives, and it may be of independent interest.
With the rapid development of quantum computers, proofs of quantumness have recently become an interesting and intriguing research direction. However, in all current schemes for proofs of quantumness, quantum provers almost invariably face the risk of being maliciously exploited by classical verifiers. In fact, through malicious strategies in interaction with quantum provers, classical verifiers could solve some instances of hard problems that arise from the specific scheme in use. In other words, malicious verifiers can break some schemes (that quantum provers are not aware of) through interaction with quantum provers. All this is due to the lack of formalization that prevents malicious verifiers from extracting useful information in proofs of quantumness. To address this issue, we formalize zero-knowledge proofs of quantumness. Intuitively, the zero-knowledge property necessitates that the information gained by the classical verifier from interactions with the quantum prover should not surpass what can be simulated using a simulated classical prover interacting with the same verifier. As a result, the new zero-knowledge notion can prevent any malicious verifier from exploiting quantum advantage. Interestingly, we find that the classical zero-knowledge proof is sufficient to compile some existing proofs of quantumness schemes into zero-knowledge proofs of quantumness schemes. Due to some technical reason, it appears to be more general to require zero-knowledge proof on the verifier side instead of the prover side. Intuitively, this helps to regulate the verifier's behavior from malicious to be honest-but-curious. As a result, both parties will play not only one role in the proofs of quantumness but also the dual role in the classical zero-knowledge proof. Specifically, the two principle proofs of quantumness schemes: Shor's factoring-based scheme and learning with errors-based scheme in [Brakerski et al, FOCS, 2018], can be transformed into zero-knowledge proofs of quantumness by requiring an extractable non-interactive zero-knowledge argument on the verifier side. Notably, the zero-knowledge proofs of quantumness can be viewed as an enhanced security notion for proofs of quantumness. To prevent malicious verifiers from exploiting the quantum device's capabilities or knowledge, it is advisable to transition existing proofs of quantumness schemes to this framework whenever feasible.
As a popular decentralized and distributed database exhibiting transparency and unforgeability, blockchain has received widespread attention. At the time of writing, its security hinges on classical cryptography, which maintains a high grade of security by exploiting the potentially excessive computational complexity of mathematical problems to be solved by state-of-the-art computers. However, as computational technology develops, this encryption philosophy is likely to be challenged and there is a risk of âstore now and decrypt laterâ attacks. A compelling solution to this security threat is to intrinsically integrate blockchain with quantum technology. Against this background, we propose a quantum blockchain scheme relying on quantum secure direct communication (QSDC). Specifically, we conceive QSDC-based blockchain for identity verification, message encryption, and consensus. We also propose an optical network based realization of the proposed QSDC-aided blockchain using present-day technology. Our simulations quantify the benefits of the scheme, especially in terms of its resource utilization. This work provides a new prospect for the intrinsic fusion of quantum information technology and blockchain technology, paving the way for its rapid commercialization.
Abstract Blockchain technology ensures accountability, transparency, and redundancy, but its reliance on publicâkey cryptography makes it vulnerable to quantum computing threats. This article addresses the urgent need for quantumâsafe blockchain solutions by integrating postâquantum cryptography (PQC) into blockchain frameworks. Utilizing algorithms from the NIST PQC standardization process, it is aimed to fortify blockchain security and resilience, particularly for IoT and embedded systems. Despite the importance of PQC, its implementation in blockchain systems tailored for embedded environments remains underexplored. A quantumâsecure blockchain architecture is proposed, evaluating various PQC primitives and optimizing transaction sizes through techniques such as publicâkey recovery for Falcon, achieving up to 17% reduction in transaction size. The analysis identifies Falconâ512 as the most suitable algorithm for quantumâsecure blockchains in computerâbased environments and XMSS as a viable but unsatisfactory stateful alternative. However, for embeddedâbased blockchains, Dilithium demonstrates a higher transactionsâperâsecond (TPS) rate compared to Falcon, primarily due to Falcon's slower signing performance on ARM CPUs. This highlights the signing time as a critical limiting factor within embedded blockchains. Additionally, smart contract functionality is integrated, assessing the impact of PQC on smart contract authentication. The findings demonstrate the feasibility and practicality, paving the way for robust and futureâproof IoT applications.
The field of quantitative finance is constantly seeking new tools to exploit the complexities of the financial markets. With classical computers having limitations, the burgeoning field of quantum computing offers immense computational capabilities. Though Belief Networks have been useful in quantitative finance, their towering computational demands on classical systems limit their efficacy. On the other hand, Bitcoinâs popularity has increased in the last few years due to its unique features, such as decentralization and blockchain. Being relatively new Bitcoinâs market possesses huge potential. Price of the Bitcoin depends upon various economic and market factors, also possesses quite high volatility making traders worried while dealing with it. This project tries explore the potential of quantum computing technologies and Belief networks for developing new long-short Bitcoin trading strategy by leveraging the strengths of both paradigms.
The end-to-end verifiable e-voting system Ordinos [26] is primarily characterized by its tally-hiding property, which ensures that only the actual election result, e. g., the winner of the election, is revealed while the full tally consisting of the aggregated votes stays hidden. Ordinos is an abstract model that guarantees tally-hiding, verifiability and vote privacy if the underlying cryptographic primitives satisfy certain requirements. It uses a multi-party-computation protocol over an additively homomorphic encryption scheme and guarantees active security with zero-knowledge proofs. Ordinos has already been instantiated for several election systems using the Paillier [35] encryption scheme, which can be broken by Shorâs algorithm [41]. The aim of this thesis is to instantiate Ordinos post-quantum secure using a variant of Regevâs LWE-based cryptosystem [39], which is adapted to realize an actively secure threshold encryption scheme over an arbitrary plaintext space. Then a noise analysis of the arithmetic and logical components used in the MPC-protocol of the Paillier instantiation is conducted, and the components are slightly adapted to restrict the noise growth. Additionally, valid zero-knowledge proofs are provided and a concrete instantiation achieving a security level of 128 bits is shown.
Joon Sik Kim, Kwangsu Lee, Jong Hwan Park, Hyoseung Kim
A threshold key encapsulation mechanism (TKEM) facilitates the secure distribution of session keys among multiple participants, allowing key recovery through a threshold number of shares. TKEM has gained significant attention, especially for decentralized systems, including blockchains. However, existing constructions often rely on trusted setups, which pose security risks such as a single point of failure and are limited by fixed participant numbers and thresholds. To overcome this issue, we propose a dynamic TKEM with a transparent setup, allowing for a flexible selection of both recipients and thresholds without relying on trusted third parties in the setup phase. In addition, our construction does not rely on pairing operations, which are less efficient compared to exponentiation. We prove the selective chosen-ciphertext security of our construction under the decisional Diffie-Hellman assumption, zero-knowledge, and soundness of a non-interactive zero-knowledge (NIZK) proof system. We also show that our scheme satisfies decapsulation consistency when the underlying NIZK system is sound. Our proof-of-concept implementation highlights the practicality and efficiency of this approach, further advancing the field of threshold cryptography.
The intersection of quantum urbanism and non-fungible tokens (NFTs) offers a new paradigm for remapping urban futures, wherein digital and physical realms merge into dynamic, decentralized ecosystems. This article examines how quantum computing, by applying principles such as superposition and probabilistic optimization, can simulate extremely intricate urban systems, from energy networks to traffic patterns, with unprecedented efficiency. Meanwhile, NFTs are transforming the notion of virtual land ownership, allowing decentralized control and hybrid economies that bypass geographical constraints. By integrating these domains, cities can become vibrant spaces where quantum algorithms optimize virtual land value, and NFT-based platforms democratize urban development. However, this transformation poses fundamental challenges: the energy consumption of quantum-blockchain infrastructures risks compromising sustainability goals, while algorithmic opacity and digital divides risk reproducing historical inequalities in virtual realms. Ethical governance policy and principles must concentrate on renewable energy integration, algorithmic transparency, and fair access to prevent exploitation. Drawing from emergent metaverse economy trials and quantum urban simulations, the paper argues that such a nexus would be capable of driving Sustainable Development Goals (SDGs), namely SDG 9 (innovation), SDG 11 (sustainable cities), and SDG 17 (partnerships) if they are premised on participatory design and cross-sectoral collaboration.
Blockchain technology has revolutionized secure and decentralized digital transactions. However, the emergence of quantum computing presents a significant threat to traditional cryptographic protocols, particularly public-key encryption mechanisms such as RSA and Elliptic Curve Cryptography (ECC). Quantum computers, leveraging Shorâs and Groverâs algorithms, can efficiently break these encryption schemes, compromising blockchain security. This paper explores quantum-secure blockchain protocols that integrate post-quantum cryptographic (PQC) techniques such as lattice-based, hash-based, and code-based cryptography to resist quantum attacks. Additionally, we evaluate quantum-resistant consensus mechanisms like Quantum-Secure Proof of Stake (QS-PoS) and Quantum-Protected Byzantine Fault Tolerance (Q-BFT). Through simulation-based performance analysis, we demonstrate that quantum-safe blockchain models can achieve robust security while maintaining efficient transaction processing. Our findings suggest that a hybrid approach, combining classical cryptographic elements with post-quantum algorithms, provides the best balance between security, performance, and scalability.