The issue of market efficiency for cryptocurrency exchanges has been largely unexplored. Here we put Bitcoin, the leading cryptocurrency, on a test by studying the applicability of the Efficient Market Hypothesis by Fama from two viewpoints: (1) the existence of profitable arbitrage spread among Bitcoin exchanges, and (2) the possibility to predict Bitcoin prices in EUR (time period 2013-2017) and the direction of price movement (up or down) on the daily trading scale. Our results show that the Bitcoin market in the time period studied is partially inefficient. Thus the market process is predictable to a degree, hence not a pure martingale. In particular, the F-measure for XBTEUR time series obtained by three major recurrent neural network based machine learning methods was about 67%, i.e. a way above the unbiased coin tossing odds of 50% equal chance.
Mustafa Al-Bassam, Alberto Sonnino, Vitalik Buterin
Light clients, also known as Simple Payment Verification (SPV) clients, are\nnodes which only download a small portion of the data in a blockchain, and use\nindirect means to verify that a given chain is valid. Typically, instead of\nvalidating block data, they assume that the chain favoured by the blockchain's\nconsensus algorithm only contains valid blocks, and that the majority of block\nproducers are honest. By allowing such clients to receive fraud proofs\ngenerated by fully validating nodes that show that a block violates the\nprotocol rules, and combining this with probabilistic sampling techniques to\nverify that all of the data in a block actually is available to be downloaded,\nwe can eliminate the honest-majority assumption, and instead make much weaker\nassumptions about a minimum number of honest nodes that rebroadcast data. Fraud\nand data availability proofs are key to enabling on-chain scaling of\nblockchains (e.g. via sharding or bigger blocks) while maintaining a strong\nassurance that on-chain data is available and valid. We present, implement, and\nevaluate a novel fraud and data availability proof system.\n
This paper examines the relationship between fiscal federalism and social policy in India through an analysis of the effects of a recent effort to increase fiscal decentralization to state governments on the nature of social policy investment at the sub-national level. Through its analysis, this paper highlights the persistence of a strong centralisation bias in India’s fiscal architecture for social policy. We trace this centralisation bias to the political and administrative dynamics of the federal bargain. The peculiar dynamics of this bargain have created a context where the core goal of centralization – to ensure equity – is undermined while the expectation of decentralization – greater accountability through alignment of expenditure with local needs and preferences, fails to take root. India is thus likely to continue to witness significant regional variation in social policy outcomes, despite a centralised financing architecture.
Abstra k : Perkembangan perekonomian dunia khususnya di Indonesia tidak dapat dilepaskan dari unsur teknologi informasi. Perkembangan teknologi informasi akan berhubungan dengan seluruh bidang termasuk bidang keuangan. Mata uang kripto (Cryptocurrency) atau sering disebut dengan mata uang virtual/digital merupakan hasil dari sebuah perkembangan teknologi keuangan (financial technology). Mata uang digital mulai banyak digunakan sebagai alat pembayaran pada internet. Tujuan mata uang ini dibuat adalah untuk memberikan kemudahan dan keamanan dalam pembayaran. Dengan adanya teknologi Blockchain didalamnya, menjadikan membuat biaya transaksi menjadi lebih murah. Namun, Pemerintah dalam hal ini Bank Indonesia melarang transaksi dengan menggunakan uang digital/virtual karena memiliki dampak berbahaya terhadap Sistem Keuangan, Stabilitas Moneter dan Sistem Pembayaran di Indonesia. Penelitian ini menjelaskan dampak dari Cryptocurrency terhadap Perekonomian Indonesia dan sikap pemerintah terhadap teknologi yang ada didalamnya. Dari sisi teknologi yang ditawarkan, cryptocurrency merupakan perkembangan dari teknologi keuangan yang memungkinkan akan mengganti uang kertas menjadi uang digital dalam transaksi keuangan dimasa depan. Diharapkan pemerintah dapat mengkaji teknologi yang terdapat pada cryptocurrency dengan lebih mendalam sehingga kebijakan yang dibuat nantinya tidak melarang teknologi yang terdapat pada cryptocurrency serta memberikan pengetahuan kepada masyarakat agar lebih memahami tentang cryptocurrency. Kata Kunci : Blockchain, Cryptocurrency, uang virtual/digital, financial technology, internet
The Bitcoin protocol is a significant milestone in the history of money. However, its adoption is currently constrained by the transaction limits of the system. As the chief problem of blockchain technology, the scaling issue has attracted many valuable solutions both on-chain and off-chain. In this paper, our goal is to explore the notion of unspent transaction outputs (UTXOs) to propose an augmented Bitcoin protocol that can scale gracefully. Our proposal aims to increase the transaction throughput by partitioning the UTXO space and splitting the blockchain. In addition, a new type of Bitcoin node is introduced to preserve the capability to run validating nodes in low-bandwidth environments, despite the increased transaction throughput.
Sep 22, 2018·2018 IEEE SmartWorld, Ubiquitous Intelligence & Computing, Advanced & Trusted Computing, Scalable Computing & Communications, Cloud & Big Data Computing, Internet of People and Smart City Innovation
Bitcoin, as a decentralized digital currency, has caused extensive research interest. There are many studies based on related protocols on Bitcoin, Bitcoin-based voting protocols also received attention in related literature. In this paper, we propose a Bitcoin-based decentralized privacy-preserving voting mechanism. It is assumed that there are n voters and m candidates. The candidate who obtains t ballots can get x Bitcoins from each voter, namely nx Bitcoins in total. We use a shuffling mechanism to protect voter's voting privacy, at the same time, decentralized threshold signatures were used to guarantee security and assign voting rights. The protocol can achieve correctness, decentralization and privacy-preservings. By contrast with other schemes, our protocol has a smaller number of transactions and can achieve a more functional voting method.
Elena Kirillova, Albert Valentinovich Pavlyuk, I. A. Mikhaylova, Зульфугарзаде Теймур Эльдарович · 5 authors
The current article examines the peculiarities and legal nature of Bitcoin, Lifecoin, Namecoin, Quark, WebMoney, Ripple and other virtual currencies. There is no single understanding of the legal essence of virtual currency in the world today; therefore, the legal status of such currencies is not officially fixed and there are no official rates of Bitcoins or other crypto currencies against national currencies. Their rate is determined in the course of trading at virtual Bitcoin exchanges and exchange platforms. Such a situation is dictated by the novelty of legal relations in the field of crypto currency circulation, the risks of their implementation, as well as security problems. The main goal of the study is to define the legal nature and features of virtual currencies and the possibilities of legislative regulation of using crypto currencies. When writing the article, the methods of collecting and studying singularities have been used, as well as generalization methods, the methods of scientific abstraction, and the methods of studying regularities. The study has concluded that it is advisable to provide for the licensing of mining and crypto trading at the international level, customers should be identified when selling and buying virtual currencies, introducing a special verification procedure for Bitcoin users will prevent the abuse of virtual currencies for money laundering and terrorism financing. As a result of the analysis, a definition has been given, and the main features and functions of the virtual currency have been highlighted. It has been proved that virtual currencies are a new kind of electronic money stored in computer memory, the monetary value of the virtual currency is managed by means of a technical device. Virtual currency is a new means of payment and does not require access to deposit accounts.
Ravi Kiran Raman, Roman Vaculín, Michael Hind, Sekou L. Remy · 9 authors
Large-scale computational experiments, often running over weeks and over large datasets, are used extensively in fields such as epidemiology, meteorology, computational biology, and healthcare to understand phenomena, and design high-stakes policies affecting everyday health and economy. For instance, the OpenMalaria framework is a computationally-intensive simulation used by various non-governmental and governmental agencies to understand malarial disease spread and effectiveness of intervention strategies, and subsequently design healthcare policies. Given that such shared results form the basis of inferences drawn, technological solutions designed, and day-to-day policies drafted, it is essential that the computations are validated and trusted. In particular, in a multi-agent environment involving several independent computing agents, a notion of trust in results generated by peers is critical in facilitating transparency, accountability, and collaboration. Using a novel combination of distributed validation of atomic computation blocks and a blockchain-based immutable audits mechanism, this work proposes a universal framework for distributed trust in computations. In particular we address the scalaibility problem by reducing the storage and communication costs using a lossy compression scheme. This framework guarantees not only verifiability of final results, but also the validity of local computations, and its cost-benefit tradeoffs are studied using a synthetic example of training a neural network.
The bitcoin price has surged in recent years and it has also exhibited phases of rapid decay. In this paper we address the question to what extent this novel cryptocurrency market can be viewed as a classic or semi-efficient market. Novel and robust tools for estimation of multi-fractal properties are used to show that the bitcoin price exhibits a very interesting multi-scale correlation structure. This structure can be described by a power-law behavior of the variances of the returns as functions of time increments and it can be characterized by two parameters, the volatility and the Hurst exponent. These power-law parameters, however, vary in time. A new notion of generalized Hurst exponent is introduced which allows us to check if the multi-fractal character of the underlying signal is well captured. It is moreover shown how the monitoring of the power-law parameters can be used to identify regime shifts for the bitcoin price. A novel technique for identifying the regimes switches based on a goodness of fit of the local power-law parameters is presented. It automatically detects dates associated with some known events in the bitcoin market place. A very surprising result is moreover that, despite the wild ride of the bitcoin price in recent years and its multi-fractal and non-stationary character, this price has both local power-law behaviors and a very orderly correlation structure when it is observed on its entire period of existence.
In Internet of Vehicles (IoV), data sharing among vehicles is essential to improve driving safety and enhance vehicular services. To ensure data sharing security and traceability, highefficiency Delegated Proof-of-Stake consensus scheme as a hard security solution is utilized to establish blockchain-enabled IoV (BIoV). However, as miners are selected from miner candidates by stake-based voting, it is difficult to defend against voting collusion between the candidates and compromised high-stake vehicles, which introduces serious security challenges to the BIoV. To address such challenges, we propose a soft security enhancement solution including two stages: (i) miner selection and (ii) block verification. In the first stage, a reputation-based voting scheme for the blockchain is proposed to ensure secure miner selection. This scheme evaluates candidates' reputation by using both historical interactions and recommended opinions from other vehicles. The candidates with high reputation are selected to be active miners and standby miners. In the second stage, to prevent internal collusion among the active miners, a newly generated block is further verified and audited by the standby miners. To incentivize the standby miners to participate in block verification, we formulate interactions between the active miners and the standby miners by using contract theory, which takes block verification security and delay into consideration. Numerical results based on a real-world dataset indicate that our schemes are secure and efficient for data sharing in BIoV.
This chapter elaborates the fourth industrial revolution and its components within the scope of Industry 4.0 and blockchain and cryptocurrencies. It presents the scope of blockchain technology and its correlation with Industry 4.0. The chapter highlights the changes that blockchain can bring in the industrial architecture with a potential use case. As the previous industrial revolution was led by innovations in manufacturing processes and systems, the advancement of Industry 4.0 will be driven by a smart, interconnected, pervasive environment. Davies of European Parliament also defined the fourth industrial revolution in 2015 as follows: Industry 4.0 is a term applied to a group of rapid transformations in the design, manufacture, operation and service of manufacturing systems and products. Manufacturing industries of the fourth industrial revolution will have the abovementioned components. Since both blockchain and Industry 4.0 are in their infancy, there will be technical and social issues and challenges on their adaptation.
We consider the problem of single-round private information retrieval (PIR) from N replicated databases. We consider the case when B databases are outdated (unsynchronized), or even worse, adversarial (Byzantine), and therefore, can return incorrect answers. In the PIR problem with Byzantine databases (BPIR), a user wishes to retrieve a specific message from a set of M messages with zero-error, irrespective of the actions performed by the Byzantine databases. We consider the T-privacy constraint in this paper, where any T databases can collude, and exchange the queries submitted by the user. We derive the information-theoretic capacity of this problem, which is the maximum number of correct symbols that can be retrieved privately (under the T-privacy constraint) for every symbol of the downloaded data. We determine the exact BPIR capacity to be C = (N -2B)/N·(1-T/(N-2B))/(1-(T/(N - 2B))M), if 2B + T <; N. This capacity expression shows that the effect of Byzantine databases on the retrieval rate is equivalent to removing 2B databases from the system, with a penalty factor of (N - 2B)/N, which signifies that even though the number of databases needed for PIR is effectively N - 2B, the user still needs to access the entire N databases. The result shows that for the unsynchronized PIR problem, if the user does not have any knowledge about the fraction of the messages that are missynchronized, the single-round capacity is the same as the BPIR capacity. Our achievable scheme extends the optimal achievable scheme for the robust PIR (RPIR) problem to correct the errors introduced by the Byzantine databases as opposed to erasures in the RPIR problem. Our converse proof uses the idea of the cut-set bound in the network coding problem against adversarial nodes.
U diplomskom radu "Primjena Ethereum pametnih ugovora na blockchain mreži" detaljno je opisana blockchain tehnologija s naglaskom na Ethereum mrežu kao i programski jezik Solidity. Kreiran je pametni ugovor s pripadajućim front end-om koji korisniku omogućuje razmjenu imovine prema cijeni koju može sam definirati.
We study the probabilistic distribution of the confirmation time of Bitcoin transactions, conditional on the current memory pool (i.e., the queue of transactions awaiting confirmation). The results of this paper are particularly interesting for users that want to make a Bitcoin transaction during `heavy-traffic situations', when the transaction demand exceeds the block capacity. In such situations, Bitcoin users tend to bid up the transaction fees, in order to gain priority over other users that pay a lower fee. We argue that the time until a Bitcoin transaction is confirmed can be modelled as a particular stochastic fluid queueing process (to be precise: a Cramér-Lundberg process). We approximate the queueing process in two different ways. The first approach leads to a lower bound on the confirmation probability, which becomes increasingly tight as traffic decreases. The second approach relies on a diffusion approximation with a continuity correction, which becomes increasingly accurate as traffic intensifies. The accuracy of the approximations under different traffic loads are evaluated in a simulation study.
The smart community (SC), as an important part of the Internet of Energy (IoE), can facilitate integration of distributed renewable energy sources and electric vehicles (EVs) in the smart grid. However, due to the potential security and privacy issues caused by untrusted and opaque energy markets, it becomes a great challenge to optimally schedule the charging behaviors of EVs with distinct energy consumption preferences in SC. In this paper, we propose a contract-based energy blockchain for secure EV charging in SC. First, a permissioned energy blockchain system is introduced to implement secure charging services for EVs with the execution of smart contracts. Second, a reputation-based delegated Byzantine fault tolerance consensus algorithm is proposed to efficiently achieve the consensus in the permissioned blockchain. Third, based on the contract theory, the optimal contracts are analyzed and designed to satisfy EVs' individual needs for energy sources while maximizing the operator's utility. Furthermore, a novel energy allocation mechanism is proposed to allocate the limited renewable energy for EVs. Finally, extensive numerical results are carried out to evaluate and demonstrate the effectiveness and efficiency of the proposed scheme through comparison with other conventional schemes.
Today, the number of Internet of Things (IoT) devices in all aspects of life is increasing exponentially. Our cities are getting smarter and informing us about our surroundings in a contextual manner. However, we face significant challenges in deploying, managing, and collecting data from these devices. In addition, we must address the problem of storing and mining that data for higher-quality IoT services. Blockchain technology, even in today's nascent form, has the potential to be the foundation for a common, distributed, trustless, and autonomous infrastructure system. This article describes a standardized IoT infrastructure where data are stored on a distributed storage service that is fault-tolerant and resistant to distributed denial of service (DDOS) attacks and data access is managed by a decentralized, trustless blockchain. The illustrated system used LoRa as the emerging network technology, Swarm as the distributed data storage platform, and Ethereum as the blockchain platform. Such a data back end will ensure high availability with minimal security risks while replacing traditional back-end systems with a single "smart contract".
Cryptocurrency is a digital form of money, instead of physical notes and coins. Cryptocurrencies are data stored through digital codes and accessed through various applications and software. Cryptocurrency is the most common name for blackchain-based money but it can also be called Digital money, Digital coins or Virtual money, took the world by lighting storm in 2017. Cryptocurrency is not only about money- it is about technology, sociology, business and innovation. In 2017, according to Business Insider, new companies raised more than $3.5 billion in initial coin offerings. As of January 2018, about 1400 Cryptocurrencies were trading hands and they continue to proliferate, raising money through initial coin offerings. This paper explores the users’ confidence of dealing with cryptocurrency in a time that using such virtual money is not fully controlled and regulated.
Fintech, which is a shorthand expression for financial technology, is basically referring to all the technological innovations in the financial sector that started to develop exponentially, especially in the second decade of the 21st century, in the era of the mobile internet revolution.The Generation Z, also called Gen Tech, who was growing up using the internet and especially the mobile internet on a daily basis, will probably be the larger adopter and beneficiary of these innovative financial technologies.The current generation of students, born about twenty years ago, is part of this cohort and this is why we decided to initiate a study regarding their perception and behavior concerning the fintech area with the help of a questionnaire applied on some of the students of the Faculty of European Studies from Babeș-Bolyai University.Because the fintech is covering financial innovations from a very broad area (including cryptocurrency, online payments, financial transfers, openbanking, investments, regtech, insurtech, etc.) we decided to focus in this preliminary study, only on the blockchain technology and cryptocurrencies and in relation to these, on the online payments.
The Bitcoin protocol prevents the occurrence of double-spending (DS), i.e. the utilization of the same currency unit more than once. At the same time a DS attack, where more conflicting transactions are generated, might be performed to defraud a user, e.g. a merchant. Therefore, in this work, we propose a model for detecting the presence of conflicting transactions by means of an 'oracle' that polls a subset of nodes of the Bitcoin network. We assume that the latter has a complex structure. So, we investigate the relation between the topology of several complex networks and the optimal amount, and distribution, of a subset of nodes chosen by the oracle for polling. Results show that small-world networks require to poll a smaller amount of nodes than regular networks. In addition, in random topologies, a small number of polled nodes can make a detection system fast and reliable even if the underlying network grows.