Alessandro Chiesa, Michael A. Forbes, Tom Gur, Nicholas Spooner
Zero knowledge plays a central role in cryptography and complexity. The seminal work of Ben-Or et al. (STOC 1988) shows that zero knowledge can be achieved unconditionally for any language in NEXP , as long as one is willing to make a suitable physical assumption : if the provers are spatially isolated, then they can be assumed to be playing independent strategies. Quantum mechanics, however, tells us that this assumption is unrealistic, because spatially-isolated provers could share a quantum entangled state and realize a non-local correlated strategy. The MIP * model captures this setting. In this work, we study the following question: Does spatial isolation still suffice to unconditionally achieve zero knowledge even in the presence of quantum entanglement? We answer this question in the affirmative: we prove that every language in NEXP has a 2-prover zero knowledge interactive proof that is sound against entangled provers; that is, NEXP ⊆ ZK-MIP * . Our proof consists of constructing a zero knowledge interactive probabilistically checkable proof with a strong algebraic structure, and then lifting it to the MIP * model. This lifting relies on a new framework that builds on recent advances in low-degree testing against entangled strategies, and clearly separates classical and quantum tools. Our main technical contribution is the development of new algebraic techniques for obtaining unconditional zero knowledge; this includes a zero knowledge variant of the celebrated sumcheck protocol, a key building block in many probabilistic proof systems. A core component of our sumcheck protocol is a new algebraic commitment scheme, whose analysis relies on algebraic complexity theory.
Online portals include an increasing amount of user feedback in form of ratings and reviews. Recent research highlighted the importance of this feedback and confirmed that positive feedback improves product sales figures and thus its success. However, online portals' operators act as central authorities throughout the overall review process. In the worst case, operators can exclude users from submitting reviews, modify existing reviews, and introduce fake reviews by fictional consumers. This paper presents ReviewChain, a decentralized review approach. Our approach avoids central authorities by using blockchain technologies, decentralized apps and storage. Thereby, we enable users to submit and retrieve untampered reviews. We highlight the implementation challenges encountered when realizing our approach on the public Ethereum blockchain. For each implementation challange, we discuss possible design alternatives and their trade-offs regarding costs, security, and trustworthiness. Finally, we analyze which design decision should be chosen to support specific trade-offs and present resulting combinations of decentralized blockchain technologies, also with conventional centralized technologies.
Initial Coin Offerings (ICO) are public offers of new cryptocurrencies in exchange of existing ones, aimed to finance projects in the blockchain development arena. In the last 8 months of 2017, the total amount gathered by ICOs exceeded 4 billion US$, and overcame the venture capital funnelled toward high tech initiatives in the same period. A high percentage of ICOS is managed through Smart Contracts running on Ethereum blockchain, and in particular to ERC-20 Token Standard Contract. In this work we examine 1388 ICOs, published on December 31, 2017 on icobench.com Web site, gathering information relevant to the assessment of their quality and software development management, including data on their development teams. We also study, at the same date, the financial data of 450 ICO tokens available on coinmarketcap.com Web site, among which 355 tokens are managed on Ethereum blochain. We define success criteria for the ICOs, based on the funds actually gathered, and on the behavior of the price of the related tokens, finding the factors that most likely influence the ICO success likeliness.
Initial Coin Offerings (ICO) are public offers of new cryptocurrencies in\nexchange of existing ones, aimed to finance projects in the blockchain\ndevelopment arena. In the last 8 months of 2017, the total amount gathered by\nICOs exceeded 4 billion US$, and overcame the venture capital funnelled toward\nhigh tech initiatives in the same period. A high percentage of ICOS is managed\nthrough Smart Contracts running on Ethereum blockchain, and in particular to\nERC-20 Token Standard Contract. In this work we examine 1388 ICOs, published on\nDecember 31, 2017 on icobench.com Web site, gathering information relevant to\nthe assessment of their quality and software development management, including\ndata on their development teams. We also study, at the same date, the financial\ndata of 450 ICO tokens available on coinmarketcap.com Web site, among which 355\ntokens are managed on Ethereum blochain. We define success criteria for the\nICOs, based on the funds actually gathered, and on the behavior of the price of\nthe related tokens, finding the factors that most likely influence the ICO\nsuccess likeliness.\n
After comparing and contrasting with computer codes running in a central server, this paper notes that smart contracts are not in the legal sense and considers their implications for contract management and dispute prevention. It alerts that the features of are prone to generate disputes which often involve novel legal issues. The paper concludes with a brief comment on the potential use of in dispute resolution.
The cryptocurrency Bitcoin has been prominently featured in the news recently. Its ascension in value has been nothing short of extraordinary. This article briefly explains what Bitcoin is and how it works. The more challenging question is what Bitcoin—this cryptographic breakthrough—really is: currency, like the U.S. dollar, an asset, more like gold, or something else? Further, can this astonishing run-up in value continue or will Bitcoin be added to the long list of so-called "asset bubbles" that eventually burst, causing pain for those that own them?
We design and implement the first private and anonymous decentralized crowdsourcing system ZebraLancer, and overcome two fundamental challenges of decentralizing crowdsourcing, i.e., data leakage and identity breach. First, our outsource-then-prove methodology resolves the tension between the blockchain transparency and the data confidentiality to guarantee the basic utilities/fairness requirements of data crowdsourcing, thus ensuring: (i) a requester will not pay more than what data deserve, according to a policy announced when her task is published via the blockchain; (ii) each worker indeed gets a payment based on the policy, if he submits data to the blockchain; (iii) the above properties are realized not only without a central arbiter, but also without leaking the data to the open blockchain. Second, the transparency of blockchain allows one to infer private information about workers and requesters through their participation history. Simply enabling anonymity is seemingly attempting but will allow malicious workers to submit multiple times to reap rewards. ZebraLancer also overcomes this problem by allowing anonymous requests/submissions without sacrificing accountability. The idea behind is a subtle linkability: if a worker submits twice to a task, anyone can link the submissions, or else he stays anonymous and unlinkable across tasks. To realize this delicate linkability, we put forward a novel cryptographic concept, i.e., the common-prefix-linkable anonymous authentication. We remark the new anonymous authentication scheme might be of independent interest. Finally, we implement our protocol for a common image annotation task and deploy it in a test net of Ethereum. The experiment results show the applicability of our protocol atop the existing real-world blockchain.
By thinking loudly about putting the regulation of cryptocurrencies on the agenda of the G20, governments seem to have managed to keep the Bitcoin bubble from inflating into a systemic risk, so far. In a tongue-in-cheek sense, this behavior of supervisory and regulatory authorities can be described as the distributed ledger technology of financial supervision. It is distributed because it does not have a clear center. The G20 seems to be the common reference point for many actors, but it does not speak itself. It is like a shared code.
Blockchains have recently generated explosive interest from both academia and industry, with many proposed applications. But descriptions of many these proposals are more visionary projections than realizable proposals, and even basic definitions are often missing. We define "blockchain" and "blockchain network", and then discuss two very different, well known classes of blockchain networks: cryptocurrencies and Git repositories. We identify common primitive elements of both and use them to construct a framework for explicitly articulating what characterizes blockchain networks. The framework consists of a set of questions that every blockchain initiative should address at the very outset. It is intended to help one decide whether or not blockchain is an appropriate approach to a particular application, and if it is, to assist in its initial design stage.
Soon after its introduction in 2009, Bitcoin has been adopted by cyber-criminals, which rely on its pseudonymity to implement virtually untraceable scams. One of the typical scams that operate on Bitcoin are the so-called Ponzi schemes. These are fraudulent investments which repay users with the funds invested by new users that join the scheme, and implode when it is no longer possible to find new investments. Despite being illegal in many countries, Ponzi schemes are now proliferating on Bitcoin, and they keep alluring new victims, who are plundered of millions of dollars. We apply data mining techniques to detect Bitcoin addresses related to Ponzi schemes. Our starting point is a dataset of features of real-world Ponzi schemes, that we construct by analysing, on the Bitcoin blockchain, the transactions used to perform the scams. We use this dataset to experiment with various machine learning algorithms, and we assess their effectiveness through standard validation protocols and performance metrics. The best of the classifiers we have experimented can identify most of the Ponzi schemes in the dataset, with a low number of false positives.
With the development of marine observation technology and network technology, the volume of marine data growing rapidly. This brings new challenges for data storage and transmission. How to protect data security of marine big data has become an urgent problem. The traditional information security methods' characteristic is centralization. These technologies cannot provide whole process protection, e.g., data storage, data management and application of data. The blockchain technology is a novel technology, which can keep the data security and reliability by using decentralized methodology. It has aroused wide interest in the financial field. In this paper, we describe the concept, characteristics and key technologies of blockchain technology and introduce it into the field of marine data security.
Several years after the inception of the most dominant cryptocurrency, bitcoin, the European Central Bank in 2015 indicated the need for establishing legal clarity by relevant authorities through explaining how the current legal framework applies to cryptocurrencies. Three years later, no meaningful step has been taken by any of the European Union (EU) institutions including the parliament. By examining the EU’s legal framework governing payments services, including the Single Euro Payment Area (SEPA) Regulation, the Electronic Money Directive, the Payment Services Directive and the proposed AML/CTF Directive, this article concludes that (a) because the existing payment services laws apply to payments effected in currencies (legal tenders) and cryptocurrencies are not defined as currencies under the EU law or the laws of member states, they do not cover cryptocurrencies. It also argues that it is impossible to design sui generis payments services law for cryptocurrencies without curbing their essential features, especially decentralization. Lastly, the article proposes centralization and the creation of state cryptocurrency as possible solutions moving forward and examines their strengths and challenges.
In this article, the author tracks developments in bitcoin trading and considers regulatory responses. 2017 has witnessed a so-called bitcoin bubble, as entrepreneurs and professional investors rushed into the market to take a bet on the upcoming cryptocurrency age. The price of a bitcoin exceeded $19,300 in December 2017, worth only $0.06 in July 2010. The popularity of bitcoin mining and trading activities has raised legal and regulatory concerns pertaining to anti-money laundering, evasion of forex regulations, the illegal fundraising of start-ups by Initial Coin Offerings (ICOs), as well as a potential financial crisis. Global financial regulators have acted proactively to regulate bitcoin. Most recently, China, once accounting for 90% of bitcoin trading volume, issued an immediate ban of ICOs and ordered the reorganisation of three major bitcoin exchanges: OKCoin, Huobi and BTCC. Over-The-Counter (OTC) transactions have not been affected. Financial authorities in certain countries have been testing state-backed cryptocurrencies.
Mareena Fernandes, Saloni Khanna, Leandra Monteiro, Anu Thomas · 5 authors
Advancement in technological developments introduced virtual currency exchange methods viz Bitcoin, Litecoin, Ethereum and so on which are evolving rapidly. Cryptocurrencies were introduced to eliminate financial intermediaries leading to direct peer-to-peer transactions. With the spread of the global Coronavirus pandemic, the relationship between Bitcoin and the equity market has expanded. Cryptocurrencies are highly volatile but can also prove to be good investments. Cryptocurrency, being a novel technique for transaction systems, has led to a lot of confusion among investors and any rumours or news on social media has been claimed to significantly affect the prices of cryptocurrencies. The huge percentage increase/decrease in Bitcoin's price over a short period of time is an intriguing phenomenon that cannot be foreseen. For a long time, bitcoin price prediction has been a hot topic of study.In this paper, we discuss the implementation and results of the Deep Learning Bitcoin Price Prediction Model and prepare a strategy to maximize gains for investors. The paper covers to framework with a set of deep learning models, analysis methods with a fixed set of factors to predict daily Bitcoin prices and design-integration of price prediction of different cryptocurrencies using RNN (Recurrent Neural Network), LSTM (Long Short-Term Memory) and GRU (Gated recurrent units). The idea of incorporating Public Sentiment in the prediction of the hikes and falls of the Bitcoin market from Social Media platforms like Reddit and Twitter leading to meaningful predicted results. This prediction can bring confidence to the common man to invest with lesser risk and more profit. Also, this can enable the digital new-age currency to become a primary method of transaction.
A large proportion of the population in the developing world can benefit from blockchain. In this article, the authors discuss key concerns that have been raised regarding institutions in the developing world and evaluate the potential role of blockchain to address them.
Nathaniel Popper leaves in DIGITAL GOLD the following passage. But the week in Austin could not help fueling suspicion that perhaps, as in the old way of doing things, the economic benefits of all the new technology were, at least so far, accruing only a small elite, while the 99 percent that Occupy Wall Street had worried about were left reading about it at home on Twitter. Bitcoin itself faced the same concerns. Years earlier, Bitcoin had promised that it would spread its benefits to all its users, but by 2014 large chunks of Bitcoin economy were owned by a few people who had been wealthy enough before Bitcoin came along to invest in this new system. Most of the new coins being released each day were collected by a few large mining syndicates. If this was the new world, it did not seem all that different from the old one－at least not yet. This is reality of Bitcoin. It does not have stability of supply. It does not have ability of credit creation. It does not have stability of value. It does not have wide agreement as a means of settlements. It exposes itself to speculation. So in conclusion, Bitcoin could not be money at least in the near future.
This report explains the technologies which underpin blockchain digital financial ledgers, how blockchain works, potential applications for blockchain, concerns with it, and potential considerations for Congress.
The surge of savvy advancements in all spaces of human action opens new opportunities for the improvement of business forms. Things that appeared to be inconceivable 15-20 years back, for example, swift online payments, e-banking and virtual cash, have turned into a piece of our regular day to day existence. Rising and creating cryptographic forms of money give us significantly more potential outcomes. One of them is Blockchain advancement, which authorizes clients towards profit related trades without commission charges. We are toward the begin of enterprise resource planning (ERP) computerized change with the presentation of blockchain innovation, best known as a digital ledger (distributed database) behind digital money. The fundamental distinctive component of the innovation is the absence of a single centralized base for data storage. All the data is distributed between interconnected blocks, which are joined into a chain utilizing complicated algorithms. Each block stores its own snippet of data. New blocks can be added to the complete of this chain, yet they can
Emmanuelle Anceaume, Antonella Del Pozzo, Romaric Ludinard, Maria Potop-Butucaru · 5 authors
The presented work continues the line of recent distributed computing community efforts dedicated to the theoretical aspects of blockchains. This paper is the first to specify blockchains as a composition of abstract data types all together with a hierarchy of consistency criteria that formally characterizes the histories admissible for distributed programs that use them. Our work is based on an original oracle-based construction that, along with new consistency definitions, captures the eventual convergence process in blockchain systems. The paper presents as well some results on implementability of the presented abstractions and a mapping of representative existing blockchains from both academia and industry in our framework.
In this work, we propose a novel approach, called Conflicts Check Protocol (CCP), which enables preventing potential attacks on bitcoin system. Based on the observation and discovery of a common symptom that many attacks may generate, an arbitration mechanism is proposed to determine the approval or abandon of certain transactions involved in confliction. Experimental results verified our statistical assumption and proved that the CCP is robust in handling many transactions in confliction scenarios and can significantly enhance the security of the current bitcoin systems. Unlike many of the existing efforts, this work examines the security issue of bitcoin from a new perspective, which can be extended further to a much larger scope of attack analysis and prevention.
The development of quantum information platforms such as quantum computers and quantum simulators that will rival classical Turing computations are typically viewed as a threat to secure data transmissions and therefore to crypto-systems and financial markets in general. We propose to use such platforms as a proof-of-work protocol for blockchain technology, which underlies cryptocurrencies providing a way to document the transactions in a permanent decentralised public record and to be further securely and transparently monitored. We reconsider the basis of blockchain encryption and suggest to move from currently used proof-of-work schemes to the proof-of-work performed by analog Hamiltonian optimisers. This approach has a potential to significantly increase decentralisation of the existing blockchains and to help achieve faster transaction times, therefore, removing the main obstacles for blockchain implementation. We discuss the proof-of-work protocols for a few most promising optimiser platforms: quantum annealing hardware based on D-wave simulators and a new class of gain-dissipative simulators.
<p class='IJASEITAbtract'><span lang='EN-GB'>The improvement of the Quality of Life (QoL) and the enhancement of the Quality of Services (QoS) represent the main goal of every city evolutionary process. It is possible making cities smarter promoting innovative solutions by use of Information and Communication Technology (ICT) for collecting and analysing large amounts of data generated by several sources, such as sensor networks, wearable devices, and IoT devices spread among the city. The integration of different technologies and different IT systems, needed to build smart city applications and services, remains the most challenge to overcome. In the Smart City context, this paper intends to investigate the Smart Environment pillar, and in particular the aspect related to the implementation of Smart Energy Grid for citizens in the urban context. The innovative characteristic of the proposed solution consists of using the Blockchain technology to join the Grid, exchanging information, and buy/sell energy between the involved nodes (energy providers and private citizens), using the Blockchain granting ledger.</span>