Blockchain Papers

Fang Ye, Zitao Zhou, Yibing Li

No abstract is available for this record.

Sonok Mahapatra, Tyler Wooldridge, Xiaodi Wang

No abstract is available for this record.

Mauritz Kop, Mateo Aboy, Timo Minssen

Mauritz Kop is TTLF Fellow and Visiting Scholar at Stanford Law School, Stanford University; Founder of MusicaJuridica and strategic intellectual property lawyer at AIRecht, a technology consultancy firm based in Amsterdam. His present cross-disciplinary, comparative research focuses on human-centred artificial intelligence (AI), the Ethical, Legal, Socio-Economic, and Policy Implications of Quantum Technology (Quantum-ELSPI), and sustainable disruptive innovation policy pluralism. Mateo Aboy is Principal Research Scholar in Biomedical Innovation, Precision Medicine, AI & Law at the LML, University of Cambridge and Affiliated Professor and Fellow at the Centre for Advanced Studies in Biomedical Innovation Law (CeBIL), University of Copenhagen. Timo Minssen is Professor of Law and the Founding Director of the Center for Advanced Studies in Biomedical Innovation Law (CeBIL), University of Copenhagen. Specializing in IP, tech-transfer, antitrust and the regulation of health and life science innovation, he is also a senior advisor at the Swedish law firm X-officio and a Quantum Law Researcher at Lund University. Abstract One of the central goals of intellectual property rights (IPRs) and related rights is to incentivize and reward creative and innovative efforts that promote scientific and technical progress and stimulate fair competition through the distribution and commercialization of technologies. Yet, an excessive proliferation of exclusive rights can also result in fundamentally anticompetitive environments with potentially negative effects on scientific research, product development, fair distribution and equitable access to the technology. Hence, a reasonable balance must be found between the stimulation of sustainable innovation and competition, the promotion of scientific research and protection through IPRs. To reconcile these factors, each new technology has led to judicial responses and even modifications to the law. We are on the verge of a technological revolution associated with quantum technologies, including quantum computing and quantum/artificial intelligence hybrids. Its complexity and global significance are creating challenges, which could not have been foreseen when the IP system was developed. This article utilizes the insights gained from qualitative and quantitative studies to (a) inquire which IPRs and related rights are currently directed to quantum computing and (b) examine whether the strategic use of overlapping IPRs might lead to innovation distortions such as excessive anticompetitive effects and underuse associated with property fragmentation. Emphasis is laid on the question if, and if so to what degree, IP portfolio approaches could result in inappropriate proliferations of exclusive rights, raise anticommons concerns and denote unwanted concentrations of first mover market power. It concludes by outlining potential proactive responses to mitigate these risks, while addressing the major future open and closed innovation opportunities, implications and challenges posed by quantum technology in general and quantum computing in particular. Current advances in quantum technology highlight the unique characteristics, promises and perils of quantum technologies—such as the unprecedented capabilities of quantum sensors, secured communications and the potential for quantum computing to solve problems beyond the reach of classical processors by implementing quantum algorithms on programmable quantum computers. The spectrum of potential applications is vast and ranges from uses in health and life sciences (eg, modelling chemical processes at the quantum using quantum simulation) to national security (eg, military uses quantum cryptography, communications and computation). In light of these actual and potential capabilities, national governments have invested over $25 billion into quantum computing research by mid-2021,1 and some reports announce that by September 2021, the quantum technology industry has attracted more than $1 billion in venture capital.2 This will have clear implications not only for the future of business, science, government and the global power game but also for society itself.3 While the predicted consequences of quantum technology remain in part speculative, it becomes increasingly evident that the ethico-legal frameworks for incentivizing, protecting, governing and regulating quantum technologies will have to be carefully studied. These frameworks might potentially have to be adapted—or newly interpreted—considering the new realities presented by second-generation (2G) quantum devices. International organizations, such as the World Economic Forum (WEF), have therefore engaged in developing ‘the first set of principles for responsible design and adoption of quantum computing technologies in order to incentivize the development of the technology while minimizing the possible risks’.4 Consequently, scrutinizing the existing framework for IPRs and how they apply to quantum computing, including their governance and regulatory dimensions, as well the interplay of IPRs with new forms of potentially closed or more decentralized and open innovation systems, are becoming ever more relevant. One of the primary goals of IPRs and related rights, such as patents, copyrights, trade secrets and trade marks, is to reward and protect creative and innovative efforts in order to promote scientific and technical progress, as well as stimulating fair competition through the distribution and commercialization of technologies.5 For example, an effective and predictable patent protection regime is generally regarded as necessary to encourage risky and costly research in complex technologies that take a long time to reach the market but are relatively easy to copy such as many pharmaceuticals. Other IPRs, such as trade secrets, could become more relevant regarding highly complex technologies that are not so easy to copy and face less regulatory barriers. However, overprotection through IPRs can also lead to a situation that would create a fundamentally anticompetitive environment.6 For example, a proliferation of patent rights upstream could potentially hinder essential innovations further downstream in the course of scientific research and product development because each upstream patent allows its owner to create another obstacle on the road to product development, adding to the cost and slowing the pace of downstream innovation.7 Dealing with this potential dilemma, commonly referred to as the ‘Tragedy of the Anticommons’, requires a reasonable balance to be found between the stimulation of innovation competition, the enhancement of scientific research and the careful protection of intellectual property rights.8 To maintain such a reasonable balance, each new technology has involved modifications to the law. This is nothing new. The first patents, during the Industrial Revolution, were mostly directed to mechanical devices and articles of manufacture. When chemical law the existing framework to solve new problems posed by and of based on and by the of and as well as in and have also led to many and a of law and We are currently on the verge of a new technological revolution associated with quantum technologies, including quantum its complexity might create challenges, which could have been foreseen when the system was this this article (a) which IPRs and rights would be to quantum technology and (b) an of whether the strategic use of of IP rights to the of a quantum IP portfolio potentially might lead to anticompetitive of market and competition and In this it would progress in an of quantum quantum will therefore be laid on the question if, and if so to what degree, overlapping IPRs could result in an inappropriate of global exclusive rights for first and in an unwanted of market power. To these this article will first with an of what quantum computing and how it can be will which of IP are at present the of quantum will these the first of on the patent for quantum will use the insights gained from qualitative and quantitative studies to the implications and possible responses to to mitigate and to future based on the of and Quantum computing its from principles of quantum (eg, and the of the Quantum the between and and the of at the beyond classical including such as and the of is the of the the of of such as of and Quantum and general are to be in an that the of at Quantum or are the quantum of can be a or a or a of We this with a a quantum in of possible quantum In to quantum can be while of each This is as quantum quantum to the in which a potential that is in For these are quantum In quantum computing is for some of the problems on which such as and for the of and Quantum are when modelling or of using quantum These at complex However, quantum also have For example, quantum can to complex and such as the but they to these The of artificial intelligence (eg, and quantum and can solve and chemical can problems that are currently not with the of classical computers. 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James Bartusek, Dakshita Khurana

We propose a new, unifying framework that yields an array of cryptographic primitives with certified deletion. These primitives enable a party in possession of a quantum ciphertext to generate a classical certificate that the encrypted plaintext has been information-theoretically deleted, and cannot be recovered even given unbounded computational resources. - For X \in {public-key, attribute-based, fully-homomorphic, witness, timed-release}, our compiler converts any (post-quantum) X encryption to X encryption with certified deletion. In addition, we compile statistically-binding commitments to statistically-binding commitments with certified everlasting hiding. As a corollary, we also obtain statistically-sound zero-knowledge proofs for QMA with certified everlasting zero-knowledge assuming statistically-binding commitments. - We also obtain a strong form of everlasting security for two-party and multi-party computation in the dishonest majority setting. While simultaneously achieving everlasting security against all parties in this setting is known to be impossible, we introduce everlasting security transfer (EST). This enables any one party (or a subset of parties) to dynamically and certifiably information-theoretically delete other participants' data after protocol execution. We construct general-purpose secure computation with EST assuming statistically-binding commitments, which can be based on one-way functions or pseudorandom quantum states. We obtain our results by developing a novel proof technique to argue that a bit b has been information-theoretically deleted from an adversary's view once they output a valid deletion certificate, despite having been previously information-theoretically determined by the ciphertext they held in their view. This technique may be of independent interest.

Omega John Unogwu, Ruchi Doshi, Kamal Kant Hiran, Maad M. Mıjwıl

Quantum-resistant blockchains refer to cryptographic processes that are resistant to attacks via quantum computers. Present public-key algorithms depend on the difficulty of deciphering the discrete log and factorization problem of large prime numbers. Shor's algorithm can be used to break the hash signatures by quantum computers. Therefore, it is necessary for the development of a post-quantum secure signature scheme or quantum-resistant blockchain for post-quantum blockchain security. This chapter will discuss the impact quantum computers are predicted to have on public key cryptography based on the following topics: quantum computers, public key cryptography, quantum threat to PKI, Shor's and Grover's algorithms, post-quantum cryptography, and quantum-resistant blockchain.

Saeed Banaeian Far, Azadeh Imani Rad, Maryam Rajabzadeh Asaar

Quantum computing is the primary concern against security and privacy issues; And it is known that no digital assets have provable ownership in the post-quantum age. As a digital asset or investing method, cryptocurrencies are not far from this fact. This study presents a practical and comprehensive framework to secure current cryptocurrencies against quantum computers by offering a hard fork. The currently-using cryptocurrencies can apply the mentioned hard fork for providing security in the post-quantum age. To keep the currencies’ previous values in their post-quantum forks, the mentioned hard fork is designed based on a 1-to-1 proof of burn (PoB) consensus: a hash function and hash-based signature as two quantum-secure tools, are applied to prepare the migration to the quantum-secure fork. For example, and to show that the hard fork works, the quantum-secure fork of Bitcoin (QBTC) will be presented and analyzed in the heuristic form.

Sunil Pai, Tae‐Won Park, Marshall Ball, Bogdan Penkovsky · 12 authors

As blockchain technology and cryptocurrency become increasingly mainstream, ever-increasing energy costs required to maintain the computational power running these decentralized platforms create a market for more energy-efficient hardware. Photonic cryptographic hash functions, which use photonic integrated circuits to accelerate computation, promise energy efficiency for verifying transactions and mining in a cryptonetwork. Like many analog computing approaches, however, current proposals for photonic cryptographic hash functions that promise similar security guarantees as Bitcoin are susceptible to systematic error, so multiple devices may not reach a consensus on computation despite high numerical precision (associated with low photodetector noise). In this paper, we theoretically and experimentally demonstrate that a more general family of robust discrete analog cryptographic hash functions, which we introduce as LightHash, leverages integer matrix-vector operations on photonic mesh networks of interferometers. The difficulty of LightHash can be adjusted to be sufficiently tolerant to systematic error (calibration error, loss error, coupling error, and phase error) and preserve inherent security guarantees present in the Bitcoin protocol. Finally, going beyond our proof-of-concept, we define a ``photonic advantage'' criterion and justify how recent developments in CMOS optoelectronics (including analog-digital conversion) provably achieve such advantage for robust and digitally-verifiable photonic computing and ultimately generate a new market for decentralized photonic technology.

Muhammad Asad Ullah, Jason William Setiawan, Junaid ur Rehman, Hyundong Shin

Blockchain has revolutionized many fields, such as distributed sensor networks, finance, and cryptocurrency. Consensus between distributed network nodes is at the core of such blockchain technologies. The three primary performance measures for any consensus algorithm are scalability, security, and decentralization. This paper evaluates the usefulness and practicality of quantum consensus algorithms for blockchain-enhanced sensor, and computing networks and evaluates them against the aforementioned performance measures. In particular, we investigate their noise robustness against quantum decoherence in quantum processors and over fiber-optic channels. We observe that the quantum noise generally increases the error rate in the list distribution. However, the effect is variable on different quantum consensus schemes. For example, the entanglement-free scheme is more affected than entanglement-based schemes for the local noise cases, while in the case of noisy optical fiber links, the effect is prominent on all quantum consensus schemes. We infer that the current quantum protocols with noisy intermediate-scale quantum devices and noisy quantum communication can only be employed for modular units in intraenterprise-level blockchain, such as Zilliqa, for sensor, and computing networks.

M. X. Luo, Shao-Ming Fei, Jing‐Ling Chen

Quantum entanglement has shown distinguished features beyond any classical state. Many methods have been presented to verify unknown entanglement with the complete information about the density matrices by quantum state tomography. In this work, we aim to identify unknown entanglement with only partial information of the state space. The witness consists of a generalized Greenberger-Horne-Zeilinger-like paradox expressed by Pauli observables, and a nonlinear entanglement witness expressed by density matrix elements. First, we verify unknown bipartite entanglement and study the robustness of entanglement witnesses against the white noise. Second, we generalize such verification to partially unknown multipartite entangled states, including the Greenberger-Horne-Zeilinger-type and W-type states. Third, we give a quantum-information application related to the quantum zero-knowledge proof. It further provides a useful method in blindly verifying universal quantum computation resources. These results may be interesting in entanglement theories, quantum communication, and quantum networks.

Scott E. Smart, Jan-Niklas Boyn, David A. Mazziotti

The simulation of strongly correlated many-electron systems is one of the most promising applications for near-term quantum devices. Here we use a class of eigenvalue solvers [presented in Smart and Mazziotti, Phys. Rev. Lett. 126, 070504 (2021)] in which a contraction of the Schr\"odinger equation is solved for the two-electron reduced density matrix (2-RDM) to resolve the energy splittings of the ortho-, meta-, and para-isomers of benzyne ${\text{C}}_{6}{\text{H}}_{4}$. In contrast to the traditional variational quantum eigensolver, the contracted quantum eigensolver can solve an integration (or contraction) of the many-electron Schr\"odinger equation onto the two-electron space. The quantum solution of the anti-Hermitian part of the contracted Schr\"odinger equation provides a scalable approach with few variational parameters that has its foundations in 2-RDM theory. Experimentally, a variety of error-mitigation strategies enable the calculation, including a linear shift in the 2-RDM targeting the iterative nature of the algorithm as well as a projection of the 2-RDM onto the convex set of approximately $N$-representable 2-RDMs defined by the 2-positive $N$-representability conditions. The relative energies exhibit single-digit millihartree errors, capturing a large part of the electron correlation energy, and the computed natural orbital occupations reflect the significant differences in the electron correlation of the isomers.

Alexey Yu. Bykovsky

The methods of data verification are discussed, which are intended for the distant control of autonomous mobile robotic agents via networks, combining optical data links. The problem of trust servers is considered for position verification and position-based cryptography tasks. In order to obtain flexible quantum and classical verification procedures, one should use the collective interaction of agents and network nodes, including some elements of the blockchain. Multiple-valued logic functions defined within discrete k-valued Allen–Givone algebra are proposed for the logically linked list of entries and the distributed ledger, which can be used for distant data verification and breakdown restoration in mobile agents with the help of partner network nodes. A distributed ledger scheme involves the assigning by distant partners of random hash values, which further can be used as keys for access to a set of distributed data storages, containing verification and restoration data. Multiple-valued logic procedures are simple and clear enough for high-dimensional logic modelling and for the design of combined quantum and classical protocols.

Snigdha Kashyap, Bharat Bhushan, Avinash Kumar, Parma Nand

No abstract is available for this record.

P. R. Mahalingam

No abstract is available for this record.

Yijie Zhu, Qiang Ni, Richard Jiang, Ahmed Bouridane · 5 authors

No abstract is available for this record.

Jelle Don, Serge Fehr, Christian Majenz, Christian Schaffner

Commit-and-open Sigma-protocols are a popular class of protocols for constructing non-interactive zero-knowledge arguments and digital-signature schemes via the Fiat-Shamir transformation. Instantiated with hash-based commitments, the resulting non-interactive schemes enjoy tight online-extractability in the random oracle model. Online extractability improves the tightness of security proofs for the resulting digital-signature schemes by avoiding lossy rewinding or forking-lemma based extraction. In this work, we prove tight online extractability in the quantum random oracle model (QROM), showing that the construction supports post-quantum security. First, we consider the default case where committing is done by element-wise hashing. In a second part, we extend our result to Merkle-tree based commitments. Our results yield a significant improvement of the provable post-quantum security of the digital-signature scheme Picnic. Our analysis makes use of a recent framework by Chung et al. [arXiv:2010.11658] for analysing quantum algorithms in the QROM using purely classical reasoning. Therefore, our results can to a large extent be understood and verified without prior knowledge of quantum information science.

Zebo Yang, Tara Salman, Raj Jain, Roberto Di Pietro

Blockchain technology has been prominent recently due to its applications in cryptocurrency. Numerous decentralized blockchain applications have been possible due to blockchains' nature of distributed, secured, and peer-to-peer storage. One of its technical pillars is using public-key cryptography and hash functions, which promise a secure, pseudo-anonymous, distributed storage with non-repudiation. This security is believed to be difficult to break with classical computational powers. However, recent advances in quantum computing have raised the possibility of breaking these algorithms with quantum computers, thus, threatening the blockchains' security. Quantum-resistant blockchains are being proposed as alternatives to resolve this issue. Some propose to replace traditional cryptography with post-quantum cryptography—others base their approaches on quantum computer networks or quantum internets. Nonetheless, a new security infrastructure (e.g., access control/authentication) must be established before any of these could happen. This article provides a theoretical analysis of the quantum blockchain technologies that could be used for decentralized identity authentication. We put together a conceptual design for a quantum blockchain identity framework (QBIF) and give a review of the technical evidence. We investigate its essential components and feasibility, effectiveness, and limitations. Even though it currently has various limitations and challenges, we believe a decentralized perspective of quantum applications is noteworthy and likely.

Qin Li, Jiajie Wu, Junyu Quan, Jinjing Shi · 5 authors

Quantum blockchain is expected to offer an alternative to classical blockchain to resist malicious attacks laughed by future quantum computers. Although a few quantum blockchain schemes have been constructed, their efficiency is low and unable to meet application requirements due to the fact that they lack of a suitable consensus mechanism. To tackle this issue, a consensus mechanism called quantum delegated proof of stake (QDPoS) is constructed by using quantum voting to provide fast decentralization for the quantum blockchain scheme at first. Then an efficient scheme is proposed for quantum blockchain based on QDPoS, where the classical information is initialized as a part of each single quantum state and these quantum states are entangled to form the chain. Compared with previous methods, the designed quantum blockchain scheme is more complete and carried out with higher efficiency, which greatly contributes to better adapting to the challenges of the quantum era.

Ming‐Xing Luo, Shao-Ming Fei, Jing‐Ling Chen

Quantum entangled states have shown distinguished features beyond any classical state. Many methods like quantum state tomography have been presented to verify entanglement. In this work, we aim to identify unknown entanglements with partial information of the state space by developing a nonlinear entanglement witness. The witness consists of a generalized Greenberger-Horne-Zeilinger-like paradox expressed by Pauli observables, and a nonlinear inequality expressed by density matrix elements. First, we verify unknown bipartite entanglements and study the robustness of entanglement witnesses against the white noise. Second, we generalize such a verification to unknown multipartite entangled states, including the Greenberger-Horne-Zeilinger-type states and the cluster states under local channel operations. Third, we give a quantum-information application related to the quantum zero-knowledge proof. Our results provide a useful method in verifying universal quantum computation resources with robustness against white noises. Our work is applicable to detect unknown entanglement without the state tomography.

Xiaojun Wen, Yongzhi Chen, Xincan Fan, Wei Zhang · 6 authors

No abstract is available for this record.

Zhengying Cai, Shi Liu, Zhangyi Han, Rui Wang · 5 authors

Traditional anti-quantum methods and multi-signature technologies to secure the blockchain against quantum attacks will quickly reduce the efficiency and scalability of the industrial blockchain, where the computational resources will experience a polynomial rise with the increasing number of traders. Here, a quantum blind multi-signature method is proposed for the multi-party transaction to provide anti-quantum security. First, the proposed multi-party transaction frame and quantum key distribution in the industrial blockchain are introduced. It integrates a novel quantum blind multi-signature algorithm that is based on the quantum entanglement mechanism, and it is absolutely secure in theory. Second, the anti-quantum multi-signature algorithm is illustrated, where there are four phases, i.e., initialization, signing, verification, and implementation. Third, the security and complexity of the proposed framework are analyzed and compared with related methods in references, and our proposed method is verified to be able to offer good computational performance and blockchain scalability for multi-party transaction. Last, the paper is summarized and future research directions are proposed.

Kranthi Kumar Singamaneni, Kadiyala Ramana, Gaurav Dhiman, Saurabh Singh · 5 authors

As a result of the limited resources available in IoT local devices, the large scale cloud consumer's data that are produced by IoT related machines are contracted out to the cloud. Cloud computing is unreliable, using it can compromise user privacy, and data may be leaked. Because cloud-data and grid infrastructure are both growing exponentially, there is an urgent need to explore computational sources and cloud large-data protection. Numerous cloud service categories are assimilated into numerous fields, such as defense systems and pharmaceutical databases, to compute information space and allocation of resources. Attribute Based Encryption (ABE) is a sophisticated approach which can permit employees to specify a higher level of security for data stored in cloud storage facilities. Numerous obsolete ABE techniques are practical when applied to small data sets to generate cryptograms with restricted computational properties; their properties are used to generate the key, encrypt it, and decrypt it. To address the current concerns, a dynamic non-linear polynomial chaotic quantum hash technique on top of secure block chain model can be used for enhancing cloud data security while maintaining user privacy. In the proposed method, customer attributes are guaranteed by using a dynamic non- polynomial chaotic map function for the key initialization, encryption, and decryption. In the proposed model, both organized and unorganized massive clinical data are considered to be inputs for reliable corroboration and encoding. Compared to existing models, the real-time simulation results demonstrate that the stated standard is more precise than 90% in terms of bit change and more precise than 95% in terms of dynamic key generation, encipherment, and decipherment time.

Kumar Nilesh, Prasanta K. Panigrahi

The advancement of quantum computers undermines the security of classical blockchain, necessitating either a post-quantum upgrade of the existing architecture or creation of an inherently quantum blockchain. Here we propose a practically realizable model of a fully quantum blockchain based on a generalized Gram-Schmidt procedure utilizing dimensional lifting. In this model, information of transactions stored in a multi-qubit state are subsequently encoded using the generalized Gram-Schmidt process. The chain is generated as a result of the reliance of orthogonalized state on the sequence of states preceding it. Various forking scenarios and their countermeasures are considered for the proposed model. It is shown to be secure even against quantum computing attacks using the no-cloning theorem and non-democratic nature of Generalized Gram-Schmidt orthogonalization. Finally, we outline a framework for a quantum token built on the same architecture as our blockchain.

Robert R. Nerem, Daya Ram Gaur

Our aim is to determine conditions for quantum computing technology to give rise to security risks associated with quantum Bitcoin mining. Specifically, we determine the speed and energy efficiency a quantum computer needs to offer an advantage over classical mining. We analyze the setting in which the Bitcoin network is entirely classical except for a single quantum miner who has small hash rate compared to that of the network. We develop a closed-form approximation for the probability that the quantum miner successfully mines a block, with this probability dependent on the number of Grover iterations the quantum miner applies before making a measurement. Next, we show that, for a quantum miner that is "peaceful", this success probability is maximized if the quantum miner applies Grover iterations for 16 minutes before measuring, which is surprising as the network mines blocks every 10 minutes on average. Using this optimal mining procedure, we show that the quantum miner outperforms a classical computer in efficiency (cost per block) if the condition $Q < Crb$ is satisfied, where $Q$ is the cost of a Grover iteration, $C$ is the cost of a classical hash, $r$ is the quantum miner's speed in Grover iterations per second, and $b$ is a factor that attains its maximum if the quantum miner uses our optimal mining procedure. This condition lays the foundation for determining when quantum mining, and the known security risks associated with it, will arise.

Te-Yuan Lin, Chiou‐Shann Fuh

Quantum computing is no longer a thing of the future. Shor’s algorithm proved that a quantum computer couldtraverse key of factoring problems in polynomial time. Because the time-complexity of the exhaustive keysearch for quantum computing has not reliably exceeded the reasonable expiry of crypto key validity, it is believedthat current cryptography systems built on top of computational security are not quantum-safe. Quantumkey distribution fundamentally solves the problem of eavesdropping; nevertheless, it requires quantumpreparatory work and quantum-network infrastructure, and these remain unrealistic with classical computers.In transitioning to a mature quantum world, developing a quantum-resistant mechanism becomes a stringentproblem. In this research, we innovatively tackled this challenge using a non-computational difficulty schemewith zero-knowledge proof in order to achieve repellency against quantum computing cryptanalysis attacks foruniversal classical clients.