Blockchain ou Distributed Ledger Technology (DLT) apresenta uma onda de disrupção causada pela tecnologia havendo enormes oportunidades de desenvolvimento futuro. É uma das invenções fundamentais na história da ciência da computação. Apresenta um elemento faltante na Internet que é um protocolo de confiança. Analisando as principais fontes de referências em pesquisas sobre blockchain e de 81 artigos sobre o tópico na base web of science no período entre 2016 e 2018. Foram analisados aspectos das principais fontes da literatura, autores, métodos de pesquisa, países, redes de pesquisas, entre outros. Foi utilizado método bibliométrico e de text analytics para o seu desenvolvimento. Diversos pacotes do software R foram utilizados em codificação própria. Analisou-se progresso atual da tecnologia blockchain, suas limitações e tendências futuras. A pesquisa mostra que a pesquisa doméstica sobre o blockchain está em sua infância. Muitas das pesquisas internacionais ainda usam como case a análise qualitativa. Tópicos como moeda digital, Fintechs e o risco da tecnologia blockchain serão o foco de pesquisas futuras.
The recent hype about blockchain technology and its abilities has led to a reconsideration of existing structures in the field of finance. With a bigger focus on efficient transaction processing, interaction and automation, the underlying concept of a distributed ledger has also showed feasibility for a much broader field. For this reason, the objective of this article lies in a first evaluation of this technology for blockchain-driven supply chains by taking a closer look at potential use cases and existing applications, particularly supply chain operations and trade finance. By aligning all relevant data streams on a digital scale, it is possible not only to make trading processes significantly more functional, but also to improve regulatory control through elimination of redundant practices. A digital, autonomous, decentralized, and distributed network would be applicable to a countless number of services. The initial concept for trade finance provides here a foundation to close the gap between vague assumptions and practical contributions in supply chain management.
The comparative characteristic of consensus algorithms in distributed ledgers based on different technologies such as blockchain and directed acyclic graph is given in the article. Advantages and disadvantages of GHOST, Tangle and Hashgraph consensus algorithms are given, as well as recommendations of optimal variant selection.
Kripto para olarak da adlandırılan dijital para fiyatlarındaki değişimler son yıllarda yatırımcıların oldukça ilgisini çekmiştir. Hızlı fiyat değişimlerinden getiri elde etmek isteyen yatırımcılar yeni bir varlık olan dijital paralara yönelmişlerdir. Bu doğrultuda, dijital paraların geleneksel menkul kıymetlerine alternatif olma ihtimalleri tartışılmaya başlanmıştır. Çalışmada, Bitcoin fiyatları ile Borsa İstanbul arasındaki eşbütünleşme ve nedensellik ilişkisini tespit etmek amaçlanmıştır. Bu kapsamda, Engle-Granger ve Gregory-Hansen eşbütünleşme testleri ile Toda-Yamamoto ve Hacker-Hatemi-J nedensellik testlerinden faydalanılmıştır. Bulgular, her iki eşbütünleşme testine göre Bitcoin fiyatları ile Borsa İstanbul endeks değeri arasında orta ve uzun vadede bir eşbütünleşme ilişkisinin olmadığını; nedensellik testlerinden sadece Toda-Yamamoto nedensellik testine göre Borsa İstanbul’dan Bitcoin fiyatlarına doğru tek yönlü nedensellik ilişkisi olduğunu göstermiştir.
This article introduces the concept of proof of authentication (PoAh) for the lightweight implementation of blockchains in the Internet of Things (IoT). The PoAh can replace existing consensus algorithms, such as proof of work (PoW), proof of stake (PoS), and proof of activity (PoA), for resource- and energy-constrained infrastructures, such as the IoT.
With the rapid development of smart mobile terminals (MTs), various industrial Internet of things (IIoT) applications can fully leverage them to collect and share data for providing certain services. However, two key challenges still remain. One is how to achieve high-quality data collection with limited MT energy resource and sensing range. Another is how to ensure security when sharing and exchanging data among MTs, to prevent possible device failure, network communication failure, malicious users or attackers, etc. To this end, we propose a blockchain-enabled efficient data collection and secure sharing scheme combining Ethereum blockchain and deep reinforcement learning (DRL) to create a reliable and safe environment. In this scheme, DRL is used to achieve the maximum amount of collected data, and the blockchain technology is used to ensure security and reliability of data sharing. Extensive simulation results demonstrate that the proposed scheme can provide higher security level and stronger resistance to attack than a traditional database based data sharing scheme for different levels/types of attacks.
Rachid Guerraoui, Petr Kuznetsov, Matteo Monti, Matej Pavlovic · 5 authors
Many blockchain-based protocols, such as Bitcoin, implement a decentralized asset transfer (or exchange) system. As clearly stated in the original paper by Nakamoto, the crux of this problem lies in prohibiting any participant from engaging in double-spending. There seems to be a common belief that consensus is necessary for solving the double-spending problem. Indeed, whether it is for a permissionless or a permissioned environment, the typical solution uses consensus to build a totally ordered ledger of submitted transfers. In this paper we show that this common belief is false: consensus is not needed to implement of a decentralized asset transfer system. We do so by introducing AT2 (Asynchronous Trustworthy Transfers), a class of consensusless algorithms. To show formally that consensus is unnecessary for asset transfers, we consider this problem first in the shared-memory context. We introduce AT2$_{SM}$, a wait-free algorithm that asynchronously implements asset transfer in the read-write shared-memory model. In other words, we show that the consensus number of an asset-transfer object is one. In the message passing model with Byzantine faults, we introduce a generic asynchronous algorithm called AT2$_{MP}$ and discuss two instantiations of this solution. First, AT2$_{D}$ ensures deterministic guarantees and consequently targets a small scale deployment (tens to hundreds of nodes), typically for a permissioned environment. Second, AT2$_{P}$ provides probabilistic guarantees and scales well to a very large system size (tens of thousands of nodes), ensuring logarithmic latency and communication complexity. Instead of consensus, we construct AT2$_{D}$ and AT2$_{P}$ on top of a broadcast primitive with causal ordering guarantees offering deterministic and probabilistic properties, respectively.
Given the ubiquity of artificial intelligence (AI) in modern societies, it is clear that individuals, corporations, and countries will be grappling with the legal and ethical issues of its use. As global problems require global solutions, we propose the establishment of an international AI regulatory agency that --- drawing on interdisciplinary expertise --- could create a unified framework for the regulation of AI technologies and inform the development of AI policies around the world. We urge that such an organization be developed with all deliberate haste, as issues such as cryptocurrencies, personalized political ad hacking, autonomous vehicles and autonomous weaponized agents are already a reality, affecting international trade, politics, and war.
Shixiong Yao, Jing Chen, Kun He, Ruiying Du · 6 authors
In the recent years, the vulnerabilities of conventional public key infrastructure are exposed by the real-world attacks, such as the certificate authority’s single-point-of-failure or clients’ private information leakage. Aimed at the first issue, one type of approach is that multiple entities are introduced to assist the certificate operations, including registration, update, and revocation. However, it is inefficient in computation. Another type is to make the certificate information publicly visible by bringing in the log servers. Nevertheless, the data synchronization among log servers may lead to network latency. Based on the second approach, the blockchain-based public key infrastructure schemes are proposed. Through these type of schemes, all the certificate operations are stored in the blockchain for public audit. However, the issue of revoked certificates’ status storage is worth paying attention, especially in the setting with massive certificates. In addition, the target web server that a client wants to access is exposed in the process of certificate status validation. In this paper, we propose a privacy-preserving blockchain-based certificate status validation scheme called PBCert to solve these two issues. First, we separate the revoked certificates control and storage plane. Only the minimal control information (namely, certificate hashes and related operation block height) is stored in the blockchain and it uses external data stores for the detailed information about all revoked certificates. Second, we design an obscure response to the clients’ certificate status query for the purpose of privacy preserving. Through the security analysis and experiment evaluation, our scheme is significant in practice.
The challenge that journalism is facing these days in the Internet mobile environment is greater than ever before. Journalism is losing its revenue structure to platform operators favoring a certain markets, and also the trust of its readers in light of fake news and infected news. To alleviate this situation, we propose a blockchain technology that is applicable to journalism in order to achieve decentralization as a reasonable alternative. The journalism model based on hybrid blockchain aims to achieve the following: the delivery of articles with sharing value, what we call proof of sharing; the distribution of roles of personalized agenda settings; and finally, the use of agora to collect public opinions. With all these, we attempt to resolve the issues with current journalism with our proposed model based on blockchain.
Blockchain, or distributed ledger technology, has been an increasingly common topic in technical circles over the past several years. You may have read one of the thousands of articles documenting ...
Without much preparation, Indonesia in 2000 the new system replaced the previous centralized governance system and development planning with various decentralization programs. The reforms gave greater authority, political power, and financial resources directly to districts and cities, through the provinces. Strengths transferred include those who carry out various responsibilities in the fields of health, primary and secondary education, public works, environment, communication, transportation, agriculture, manufacturing, and other economic sectors. At the same time, the government replaced the cash-based public finance system, a single-entry financial system with a modern double-entry accounting system that uses one treasury account; based on performance; and has transparent public cash management, strict expenditure and financial controls with performance indicators, computerized reporting, and a tightly scheduled audit system.
This article demonstrates the possibility of constructing indicators of critical and crash phenomena in the volatile market of cryptocurrency. For this purpose, the methods of the theory of complex networks have been used. The possibility of constructing dynamic measures of network complexity behaving in a proper way during actual pre-crash periods has been shown. This fact is used to build predictors of crashes and critical events phenomena on the examples of all the patterns recorded in the time series of the key cryptocurrency Bitcoin, the effectiveness of the proposed indicators-precursors of these falls has been identified.
Blockchain applications have largely been short-lived phenomena in the (classical) corporate governance arena over the past few years. However, at the same time, blockchain has also found its place in addressing agency problems in modern organizations, such as Decentralized Autonomous Organizations (DAOs), offering valuable opportunities to eliminate classical inefficiencies. After a brief introduction to the agency problem and its associated costs in corporations, this chapter explores blockchain technology as a potential solution to this issue. Furthermore, the chapter delves into these DAOs, which, at least in theory, eliminate the agent and its accompanying problem while incorporating artificial intelligence. In the governance of more traditional corporations, blockchain should also be considered a useful tool for overcoming several agency problems and inefficiencies. However, regulatory burdens, uncertainties, as well as concerns related to accountability and other associated costs and interests, slow down the adoption of blockchain in the corporate law and governance environment.
Cryptocurrencies have gained tremendous popularity over the past few years. The purpose of this study is to try to understand the factors that are driving cryptocurrency-related trading activities. Focusing on the well-established cryptocurrency called Bitcoin, we find that online search popularity and the volume of trade in unrelated stock markets positively and negatively, respectively, influence Bitcoin trading volume. We also find no statistical evidence that the underlying sentiment behind relevant financial news influence Bitcoin trading volume. We believe these results might be of great value to investors interested in cryptocurrencies and might instigate further research on this topic.
Blockchain, as a secured, trusted, and decentralized architecture, is used to create secure and tamper-proof payment schemes, which can serve economies and societies without trusted parties. However, the transparency and traceability of blockchain severely restrict the anonymity of participants in the real world, which will cause participants' privacy leakage. Toward this end, in this paper, an anonymous off-blockchain micropayments scheme (AOM) is proposed for cryptocurrencies in the real world. In AOM, a payee receives micropayments from an “honest-but-curious” intermediary T by solving puzzles which are generated based on the standard RSA assumption. Meanwhile, T also receives micropayments from the payers by payee's solutions and T will randomly select the inputs of the merging transaction Tmer. In order to improve service efficiency of T and resist denial of service attack, one of the outputs of Tmeris paid for T as a service fee. Besides, AOM simultaneously ensures the correctness and fairness of transactions. Finally, from the analyses of property and security, AOM has strong unlinkability, ability for anti-attacks and unforgeability.
Blockchain Technology Applications and Security
Advanced Steganography and Watermarking Techniques
The online social networks facilitate naturally for the users to share information. On these platforms, each user shares information based on his or her interests. The particular information being shared by a user may be legitimate or fake. Sometimes a misinformation, propagated by users and group can create chaos or in some cases, might leads to cases of riots. Nowadays the third party like ALT news and Cobrapost check the information authenticity, but it takes too much time to validate the news. Therefore, a robust and new system is required to check the information authenticity within the network, to stop the propagation of misinformation. In this paper, we propose a blockchain based framework for sharing the information securely at the peer level. In the blockchain model, a chain is created by combining blocks of information. Each node of network propagates the information based on its credibility to its peer nodes. The credibility of a node will vary according to the respective information. Trust is calculated between sender and receiver in two ways:(i) Local trust used for sharing information at the peer level and (ii) global trust is used for a credibility check of each user in the network. We evaluate our framework using real dataset derived from Facebook. Our approach achieves an accuracy of 83% which shows the effectiveness of our proposed framework.
In this paper, reinforcement learning is applied to the problem of optimizing market making. A multi-agent reinforcement learning framework is used to optimally place limit orders that lead to successful trades. The framework consists of two agents. The macro-agent optimizes on making the decision to buy, sell, or hold an asset. The micro-agent optimizes on placing limit orders within the limit order book. For the context of this paper, the proposed framework is applied and studied on the Bitcoin cryptocurrency market. The goal of this paper is to show that reinforcement learning is a viable strategy that can be applied to complex problems (with complex environments) such as market making.
Maryna Dubinina, Svitlana Syrtseva, О. В. Буганов, N. Tusova
Introduction. Due to the rapid development of computer technology, their active implementation in all spheres of life, people began to solve everyday problems much faster. IT-technology is one of the most relevant branches of science at the modern stage of development of society, because today every company keeps records of its activities using computers. \n \nThus, in the future, the accounting sector is expected to undergo major changes, because the technology “Вlockchain” is actively implemented in the financial sector of the country. The investigated platform has an important property for accounting work, because the information created in this database can be trusted, even if there is no trust in the counterparty. The transaction is carried out only if it is approved by both parties. \n \nPurpose. The purpose of the article is to substantiate the feasibility of implementing Blockchain technology in accounting. \n \nResults. Proponents of technology believe that the new tool will be able to replace not only accountants, but also banking institutions and many financial intermediaries. According to the Blockchain Research Institute, Ukraine is included in the list of 14 countries which were recognized as leaders in the implementation of Blockchain. However, the state has to restructure huge systems with a large number of people to use this tool. It is also necessary to prepare legislation properly and take into account the fact that high energy costs are needed to support technology. \n \nThe technology aims to put an end to the traditional methods of invoicing, documentation, processing, registration, inventory systems and business payment. Вlockchain allows companies to record both sides of the transaction simultaneously in a shared workbook in real time and not store the reconciled entries of financial transactions in separate private created databases y or for the account books. The need for traditional double-entry accounting will be eliminated, as the verification of the legality of accounting will be fully automated. \n \nConclusions. Directions of use of technology in accounting require, first of all, proper preparation of legislation. Taking into account the prospects of using this tool, we can assume that the Blockchain will be used in Ukraine in 10-15 years and only when the national legislation is adapted to the new realities of the use of information technologies.
The subjects of the research are the transformation of the international financial architecture resulting from the internationalization of some currencies of the BRICS countries, mainly the yuan; the position of the BRICS currencies in the world monetary system; and a possibility of creating a common payment unit in the context of collective currencies, cryptocurrencies and similar monetary and financial products. Based on the correlation analysis of the dynamics of the BRICS currency quotations, the paper expresses a hypothesis about a possibility of concluding a monetary union and creating a common BRICS currency. The purpose of the research was to develop the principles of creating a common payment unit for the BRICS countries both for mediation of international economic relations and for wider international circulation. Based on the methods of analogy, comparative analysis, plotting and statistical forecasting, it is proved that the BRICS currency cannot be built on the cryptocurrency principles. It is stated that emission of the BRICS currency as a cryptocurrency will lead to the anarchy of currencies, which will naturally create conditions for the destruction of the monetary union, elimination of the new currency and preservation of the dollar dominance in the global monetary system. The novelty of the research findings lies in obtaining a formula for calculating the amount of the new BRICS currency needed for international circulation. The theoretical significance of the research is the development of a methodology for establishing the exchange rate of the collective currency for the BRICS countries. The practical importance of the research findings is manifested by determining a potentially new BRICS exchange rate in relation to the currencies of the leading countries, plotting the BRICS currency exchange rate trends to predict the limits of currency fluctuations in accordance with the scenarios from the most optimistic to the most pessimistic.
Cryptocurrencies have gained relevance in today's economic forum with the advent of technology and computing. Cryptocurrencies are a form of decentralized digital currency which has created a niche of investors all around the globe. The cryptographic forms of money have shown bounteous development and capital appreciation that has additionally charmed the financial specialists in the worldwide standpoint. This paper makes an endeavor to clarify what Cryptocurrencies are. It likewise tries to summon the advantages and disadvantages of the Cryptocurrencies and give some understanding into the street ahead for the Cryptocurrencies in India.