With the advent of blockchain technologies, the idea of decentralized applications has gained traction. Smart contracts permit the implementation of application logic to foster distributed systems that are capable of removing intermediaries. Hereby, lock in effects originating from isolated data storage and central authorities are mitigated. Yet, smart contracts deployed to a ledger generate dependencies on the underlying blockchain. Over time, requirements regarding contract execution may detach from the utilized blockchain due to contradicting incentives and security or performance issues. To avoid a novel form of lock in effect towards a host blockchain, we introduce a concept for smart contract portability that permits any user to migrate contract logic and state between blockchains in a flexible and verifiable manner. As the Ethereum Virtual Machine (EVM) is supported by a multitude of blockchain implementations, it poses a common execution environment for smart contracts. We provide a toolbox that facilitates smart contract portability between EVM-compatible blockchains without trust requirements in the entity executing the migration process. To prove the concept's soundness, we transfer token contracts based on the ERC20 standard as well as applications containing dependencies to other smart contracts. Our evaluation shows the validity of ported applications including their current states.
The blockchain is one of the most interesting technologies developed in recent years. Blockchain is a ledger, a register, a decentralized and public shared database, reachable by accessing a peer-to-peer network. Each unit of the register represents a block. The blocks are linked together in the same order in which they were created and are connected using cryptographic algorithms that make them and the information stored therein not modifiable. \nSoftware development needs to be supported by architectural models or blockchain oriented meta-models. The introduction of smart contracts, small computer programs stored inside the Ethereum blockchain, modifies the typical software engineering methodologies. The distributed applications developed on blockchain technologies, can in fact follow rules different from used for the development of the normal centralized applications. The blockchain is instead based on a totally different assumption: the information stored on the blockchain and therefore the smart contracts can not be modified or deleted without compromising the integrity of the blockchain itself. Moreover the smart contracts run in an isolated environment and their results must be the same whatever node they run in. They cannot access the external world that changes with time, but can access and send messages to the blockchain itself that is immutable. \nSuch an innovative context entails new challenges in software engineering. Greater emphasis on specific security and testing practices, new development tools, specific modeling languages and new metrics to evaluate software quality are needed. These new metrics are required to measure complexity, communication, decentralized systems, but also resource consumption (e.g. the so-called gas in the ethereum system). \nIn this scenario Agile methodologies, that are suited to system whose requirements are not completely understood, or tend to change, could be a good strategy of software development for blockchain applications. Some of the characteristics of the Agile methodologies are in fact present in decentralized applications (DApps). \nOne of the most interesting applications based on blockchain are the Initial Coin Offerings (ICOs). An ICO is an innovative way to raise funds and launch a startup. It is also an opportunity to take part in a project, or in a DAO (Decentralized Autonomous Organization). \nThis fund-raising tool contains however some critical issues, such as the use of tokens that have no intrinsic value and do not generate direct liquidity, and the role of investors in the startup’s management. The Lean software development, an approach that maximizes the value given to the customer, and aims to eliminate waste and optimize across organizations, could be helpful to face these critical aspects. \nThe ICOs and, more generally the decentralized applications are based on smart contracts. Considering the technological break through introduced by blockchain it is important to know characteristics and measures and quality parameters of the development process and its phases, as well as metrics to help ensure that the development process is under control to meet the product’s quality goals. This thesis analyzes the software development process of blockchain-based applications. In particular this work analyzes the following aspects. \n• Investigating software engineering activities related to ICOs, recognize the ICOs developed using Agile methods and make a comparison between the characteristics of ICOs and those of Agile ICOs. \n• Evaluating the lean startup approach as a methodology for the implementation of an ICO. \n• Analizyng smart contracts deployed on the Ethereum blockchain relatively to smart contracts features, their interaction with the blockchain, the role of the development community, and the source code characteristics.
innovations in peer-to-peer software protocols 3 commonly known as blockchain technology.These protocols make it possible for individuals to safely and securely complete transactions in digital information of some value, also known as "cryptocurrency," 4 without the need for either a central authority 5 to act as a third party or government-enforced rule of law. 6 But what happens when code fails to protect the basic rights that our existing laws have always sought to protect?Bitcoin-a cryptocurrency that is one form of blockchain information-continues to dominate the daily headlines, primarily due to its wild fluctuations in market price. 7 The all-time-high market price reached in 2017 correlates, unsurprisingly, with the record number of transactions 8 and wallet users 9 achieved.But the meteoric rise in price occurred without much public discussion of blockchain's technological innovation outside of a relatively small group of COINREPORT (July 27, 2016), https://coinreport.net/into-the-ether-ethereum/[https://perma.cc/GB9X-K53K].3. Protocols, in this sense, are the rules written into the code that govern how the software may be used.See PEDRO FRANCO, UNDERSTANDING BITCOIN:
The Ethereum block chain as a decentralized platform is so successful that many applications deployed on it. However, for the inherent transparency properties and the lack of privacy, deploying a financial application on top of it is always a challenge. In this paper, we tackle this challenge and propose an anonymous sealed-bid auction protocol based on time-released encryption atop Consortium Block chain. We adopt a strict digital certificate-based identity mechanism of the consortium block chain to permit legitimate participants, and utilize the blind signature based on elliptic curve technology to allowing anonymous participation. Moreover, a timed release public key encryption algorithm is adopted to encrypt bids and prevent auctioneer from colluding with bidders. This is completely different from the method (zero-knowledge proof) used in other papers to prevent collusion between auctioneer and bidder. We provide a specific analysis of our protocol, which shows that our protocol meets anonymity and applicability.
Smart contract platforms, the most notable of which is probably Ethereum, facilitate the development of important and diverse distributed applications (e.g., naming services and fungible tokens) in a simple manner. This simplicity stems from the inherent utility of employing the state of smart contracts to store, query and verify the validity of application data. In Ethereum, data storage incurs an underpriced, non-recurring, predefined fee. Furthermore, as there is no incentive for freeing or minimizing the state of smart contracts, Ethereum is faced with a tragedy of the commons problem with regards to its monotonically increasing state. This issue, if left unchecked, may lead to centralization and directly impact Ethereum's security and longevity. In this work, we introduce an alternative paradigm for developing smart contracts in which their state is of constant size and facilitates the verification of application data that are stored to and queried from an external, potentially unreliable, storage network. This approach is relevant for a wide range of applications, such as any key-value store. We evaluate our approach by adapting the most widely deployed standard for fungible tokens, i.e., the ERC20 token standard. We show that Ethereum's current cost model penalizes our approach, even though it minimizes the overhead to Ethereum's state and aligns well with Ethereum's future. We address Ethereum's monotonically increasing state in a two-fold manner. First, we introduce recurring fees that are proportional to the state of smart contracts and adjustable by the miners that maintain the network. Second, we propose a scheme where the cost of storage-related operations reflects the effort that miners have to expend to execute them. Lastly, we show that under such a pricing scheme that encourages economy in the state consumed by smart contracts, our ERC20 token adaptation reduces the incurred transaction fees by up to an order of magnitude.
Public key infrastructures (PKIs) are one of the main building blocks for securing communications over the Internet. Currently, PKIs are under the control of centralized authorities, which is problematic as evidenced by numerous incidents where they have been compromised. The distributed, fault tolerant log of transactions provided by blockchains and more recently, smart contract platforms, constitutes a powerful tool for the decentralization of PKIs. To verify the validity of identity records, blockchain-based identity systems store on chain either all identity records, or, a small (or even constant) sized amount of data for verifying identity records stored off chain. However, as most of these systems have never been implemented, there is little information regarding the practical implications of each design's tradeoffs. In this work, we first implement and evaluate the only provably secure, smart contract based PKI of Patsonakis et al. on top of Ethereum. This construction incurs constant-sized storage at the expense of computational complexity. To explore this tradeoff, we propose and implement a second construction which, eliminates the need for trusted setup, preserves the security properties of Patsonakis et al. and, as illustrated through our evaluation, is the only version with constant-sized state that can be deployed on the live chain of Ethereum. Furthermore, we compare these two systems with the simple approach of most prior works, e.g., the Ethereum Name Service, where all identity records are stored on the smart contract's state, to illustrate several shortcomings of Ethereum and its cost model. We propose several modifications for fine tuning the model, which would be useful to be considered for any smart contract platform like Ethereum so that it reaches its full potential to support arbitrary distributed applications.
In this paper, we present Tendermint: a Byzantine Fault Tolerant (BFT) application-based blockchain. We show that Tendermint promotes another perception of blockchain programming. Unlike Ethereum which is a blockchain holding many applications, Tendermint proposes to have one application per blockchain. We discuss the idiosyncrasies of Tendermint and how it could, potentially, ease blockchain programming and improve performance. We finish by showing weaknesses of Tendermint, good practices to adopt to hinder security attacks when handling Tendermint nodes, and some potential adjustments in the IBC protocol - an interoperability protocol designed for Tendermint. Our goal is to introduce Tendermint by showing its main characteristics over traditional blockchain platforms such as Bitcoin or Ethereum.
A blockchain can be referred to as a collection of house, phone phone and rarity or it should be non-physical, for instance, offers of Associate in Nursing affiliation. It have to records or open record that gets shared amongst participating parties. Every transaction that gets incorporated is first verified by all the participants of that transaction. Once the data gets recorded by the blockchain, can never be rewritten or changed. Thus the blockchain can be termed as a record book of all the transactions held. Cryptocurrencies, the decentralized bitcoin or say ethereum which can be termed as peertopeer computerized cash also uses the blockchain technology. This paper includes history of bitcoin, a few literary reviews, working of the blockchain and its application.
<sec> <title>BACKGROUND</title> Huge amounts of health-related data are generated every moment with the rapid development of Internet of Things (IoT) and wearable technologies. These big health data contain great value and can bring benefit to all stakeholders in the health care ecosystem. Currently, most of these data are siloed and fragmented in different health care systems or public and private databases. It prevents the fulfillment of intelligent health care inspired by these big data. Security and privacy concerns and the lack of ensured authenticity trails of data bring even more obstacles to health data sharing. With a decentralized and consensus-driven nature, distributed ledger technologies (DLTs) provide reliable solutions such as blockchain, Ethereum, and IOTA Tangle to facilitate the health care data sharing. </sec> <sec> <title>OBJECTIVE</title> This study aimed to develop a health-related data sharing system by integrating IoT and DLT to enable secure, fee-less, tamper-resistant, highly-scalable, and granularly-controllable health data exchange, as well as build a prototype and conduct experiments to verify the feasibility of the proposed solution. </sec> <sec> <title>METHODS</title> The health-related data are generated by 2 types of IoT devices: wearable devices and stationary air quality sensors. The data sharing mechanism is enabled by IOTA’s distributed ledger, the Tangle, which is a directed acyclic graph. Masked Authenticated Messaging (MAM) is adopted to facilitate data communications among different parties. Merkle Hash Tree is used for data encryption and verification. </sec> <sec> <title>RESULTS</title> A prototype system was built according to the proposed solution. It uses a smartwatch and multiple air sensors as the sensing layer; a smartphone and a single-board computer (Raspberry Pi) as the gateway; and a local server for data publishing. The prototype was applied to the remote diagnosis of tremor disease. The results proved that the solution could enable costless data integrity and flexible access management during data sharing. </sec> <sec> <title>CONCLUSIONS</title> DLT integrated with IoT technologies could greatly improve the health-related data sharing. The proposed solution based on IOTA Tangle and MAM could overcome many challenges faced by other traditional blockchain-based solutions in terms of cost, efficiency, scalability, and flexibility in data access management. This study also showed the possibility of fully decentralized health data sharing by replacing the local server with edge computing devices. </sec>
Ethereum clients execute transactions in a sequential order prescribed by the consensus protocol. This is a safe and conservative approach to blockchain transaction processing which forgoes running transactions in parallel even when doing so would be beneficial and safe, e.g., when there is no intersection in the sets of accounts that the transactions read or modify. In this work we study the degree of transaction parallelizability and present results from three different simulations using real Ethereum transaction data. Our simulations demonstrate that notable gains are achievable with parallelization, and suggest that the potential for parallelizability improves as transaction rates increase.
Maxim Eugenyevich Demenkov, Ekaterina A. Demenkova, Svetlana Andreevna Shishmanova
The article highlights the approach to processing landed property data based on Blockchain technology and Ethereum platform, which allows the transparent, decentralized and highly reliable system for network users with restricted access to personal data. A review of the platforms for creating decentralized online services has been performed; their advantages and disadvantages considered. The inventory of the fields required for work with the landed property. There have been selected tools for working with Ethereum platform: browser Mist and the high-level language Solidity. To facilitate working with the inventory there were created a site with a map based on SharePoint platform and integrated using API Yandex.map. Peculiarity of the system under consideration is the need for trust between the participants who add data to the inventory. It has been proposed to use either a system based on a credible exchange of certificates, as they provide the high level of personal data security and have a service life, i.e. they are active only for one session, or a system of criteria for calculating the combined trust and assigning it to another person. Emphasis is made on the need to take into account the context of collaboration and shared services in trust management. The use of Blockchain technology for solving a practical task, namely, processing and storing spatial data on landed property, is an efficient way to store data, which will ensure the data relevance and reliability, as well as reduce their loss
Nikos Fotiou, Vasilios A. Siris, George C. Polyzos
Despite technological advances, most smart objects in the Internet of Things\n(IoT) cannot be accessed using technologies designed and developed for\ninteracting with powerful Internet servers. IoT use cases involve devices that\nnot only have limited resources, but also they are not always connected to the\nInternet and are physically exposed to tampering. In this paper, we describe\nthe design, development, and evaluation of a smart contract-based solution that\nallows end-users to securely interact with smart devices. Our approach enables\naccess control, Thing authentication, and payments in a fully decentralized\nsetting, taking at the same time into consideration the limitations and\nconstraints imposed by both blockchain technologies and the IoT paradigm. Our\nprototype implementation is based on existing technologies, i.e., Ethereum\nsmart contracts, which makes it realistic and fundamentally secure.\n
techniques in association with the access rights of the members of the group workspaces. So, to utilize the off-blockchain storage more securely, it is desirable to prevent the external
We study selfish mining in Ethereum. The problem is combinato-rially more complex than in Bitcoin because of major differences in the reward system and a different difficulty adjustment formula. Equivalent strategies in Bitcoin do have different profitabilities in Ethereum. The attacker can either broadcast his fork one block by one, or keep them secret as long as possible and publish them all at once at the end of an attack cycle. The first strategy is damaging for substantial hashrates, and we show that the second strategy is even worse. This confirms what we already proved for Bitcoin: Selfish mining is most of all an attack on the difficulty adjustment formula. We show that the current reward for signaling uncle blocks is a weak incentive for the attacker to signal blocks. We compute the profitabilities of different strategies and find out that for a large parameter space values, strategies that do not signal blocks are the best ones. We compute closed-form formulas for the apparent hashrates for these strategies and compare them. We use a direct combinatorics analysis with Dyck words to find these closed-form formulas.
The purpose of this study is to analyze possible problems in issuing digital diplomas, using the blockchain technology, and to promote solving these problems as well as to show the possibility of practical implementation of the blockchain technology, using a test example. Materials and methods. The study included a review of bibliographic sources on the use of blockchain technologies in the education system, as well as computer modeling of the task of registering and verifying a digital diploma in the blockchain. Results. In the course of the work, a model of the process of issuing and verifying digital diplomas was built, and a number of problems related to the practical implementation of this model were also considered. At the same time, the following groups of problems that restrain the spread of blockchain in the education sector of the Russian Federation were identified: technical and technological problems (lack of a national blockchain platform); legal issues (lack of legal force of digital diplomas); organizational problems (lack of a centralized management structure that coordinates the “educational” blockchain as a single digital information space). An example was also realized, showing the hardware and technological capabilities of the implementation of the task under consideration using the currently open (freely available) platforms. To implement the proposed test case, the Ethereum blockchain network was used, in particular, its RinkeBy test network. The project implementation consisted of the following stages: creating a digital diploma file and placing it in the open file-sharing network in order to obtain the corresponding document hash; obtaining blockchain address (an electronic wallet was created using the MetaMask browser plugin, which allows for the transfer of data on a digital diploma to the blockchain); preparing data to be sent to the blockchain, where the data was a hexadecimal code, containing brief information about a digital diploma, including its hash; transferring data to the Ethereum blockchain (making a transaction); verification of transaction results in Etherscan. Conclusion. The blockchain technology provides great opportunities in improving the concept of e-learning, taking into account the current requirements of the digital economy. This technology can conceptually change the data archiving system, increase the reliability of information protection against falsification, and significantly speed up the execution of requests for information and data processing. The problems that arise can be successfully resolved, as long as that the blockchain becomes one of the principles of the unified information educational space. At the same time, the blockchain gives the following new opportunities: transparency and verifiability of the system of certification of graduates of educational institutions; the possibility of liquidation of intermediary organizations that implement a variety of support monitoring and certifying functions, associated with the “paper” requests for confirmation of diplomas; the overall reduction in paper workflow, the transfer of the classic “paper” business-processes into the information space, and as a result of all this – the practical implementation and example of the realization of the concept of digitalization of the knowledge economy.
The use of cryptocurrencies such as Bitcoin and Ethereum in performing online transactions has been on the rise in the world. Africa as a continent is not left out in the adoption of blockchain and cryptocurrencies. This paper explores the prospects and challenges of developing a cryptocurrency in Rwanda which we denote Rwandacoin. In addition, the paper discusses the potentials of Rwandacoin easing intercountry trading in East Africa.
The blockchain technology promises to transform finance, money and even governments. However, analyses of blockchain applicability and robustness typically focus on isolated systems whose actors contribute mainly by running the consensus algorithm. Here, we highlight the importance of considering trustless platforms within the broader ecosystem that includes social and communication networks. As an example, we analyse the flash-crash observed on 21st June 2017 in the Ethereum platform and show that a major phenomenon of social coordination led to a catastrophic cascade of events across several interconnected systems. We propose the concept of ``emergent centralisation'' to describe situations where a single system becomes critically important for the functioning of the whole ecosystem, and argue that such situations are likely to become more and more frequent in interconnected socio-technical systems. We anticipate that the systemic approach we propose will have implications for future assessments of trustless systems and call for the attention of policy-makers on the fragility of our interconnected and rapidly changing world.
We propose a framework for threshold cryptosystems under a permissionless-economic model in which the participants are rational profit-maximizing entities. To date, threshold cryptosystems have been considered under permissioned settings with a limited adversary. Our framework relies on an escrow service that slashes and redistributes deposits to incentivize participants to adhere desired behaviors. Today, more than ever, sophisticated escrow services can be implemented over public blockchains like Ethereum, without additional trust assumptions. The key threat to rational threshold cryptosystems is collusion---by cooperating `illegally', a subset of participants can reveal the cryptosystem's secret, which, in turn is translated to unfair profit. Our countermeasure to collusion is framing. If the escrow is notified of collusion, it rewards the framer and slashes the deposits of all other participants. We show that colluding parties find themselves in the prisoner's dilemma, where the dominant strategy is framing.
Käesolevas bakalaureusetöös tutvustatakse plokiahela tehnoloogiat, võrreldakse kahte erinevat platvormi, Ethereum ja Hyperledger Burrow, luukse kaks detsentraalsed rakendust ning viimasena analüüsitakse, kas on praktiline rakendada Hyperledger Burrow platvormi keerukamatele rakendustele nagu näiteks Caterpillar. Töö raames tutvustatakse plokiahela ja hajusraamatu tehnoloogiaid. Järgnevalt selgitatakse miks ja mis põhjustel antud tehnoloogiad võrdleva analüüsi tegemiseks valiti. Analüüs põhineb kahe näidisrakenduse võrdlemisel, näidates mis on peamised erinevused ja sarnasused Ethereum ja Hyperledger Burrow vahel.
ABSTRACT: Cryptocurrency, is it just a trend or is it the future of assets? It is a hot topic of conversation among individuals, as well as within companies. This paper will provide an overview of Cryptocurrency as well as discuss its inception, the current state, and the future outlook. As well, the paper will look at negative, neutral, and positive perceptions of Cryptocurrency from the perspective of individuals and organizations. The discussion will also look into Bitcoin, Ethereum, and Ripple, revealing how they differ from each other, even though all three are based on Blockchain Technology. Another section of the paper examines the comparison of Cryptocurrency to other assets. It will examine whether Cryptocurrency is similar to a monetary currency, such as the US Dollar, similar to common stock, such as shares in a public company or similar to money metals, such as Gold and Silver. These assets are all subject to market fluctuations, just like Cryptocurrency. KEYWORDS: Cryptocurrency, Bitcoin, Ethereum, Ripple, Blockchain Technology, Satoshi Nakamoto
In today’s world, the Blockchain technology is used for different purposes has brought an increment in the development of different Blockchain platforms, services, and utilities for storing data securely and efficiently. Quorum Blockchain, an Ethereum fork created by JPMorgan Chase, has placed itself in one of the widely used, efficient and trustful Blockchain platforms available today. Because of the importance which Quorum is contributing to the world, it is important to test and measure different aspects of the platform, not only to prove how efficient the software can be but as well as to have a clear view on what type of environment the platform could be better used. This research has been focused on testing the efficiency and speed of the transactions been sent to the platform in different types of environments, like local server nodes, virtual machine nodes and cloud instance nodes, by focusing its tests on the average of transactions per second or TPS being made. Once the tests were carried out, and results were obtained, there was a clear difference between the environments used. Using cloud instances for nodes improves the TPS for every single type of transactions over any other types of nodes. It might have been predicted that Cloud Instances would have done a better performance, but other factors could have caused the fallback in results for this type of nodes.
Донецький національний університет імені Василя Стуса, Maya M. Savchenko, В.О. Короленко, Донецький національний університет імені Василя Стуса · 6 authors
The article explores innovations in the monetary sphere, namely the emergence of a modern form of money - digital currency. Forms of this currency, such as electronic and virtual money, are defined. The dynamics of development of the first and the most expensive cryptocurrency now - Bitcoin is analyzed. The general state of the cryptocurrency usage in the world is indicated. The advantages and disadvantages of using digital currency are also highlighted. The Top-10 cryptocurrencies in the world for 2019 are highlighted with the largest market capitalization of Bitcoin, Ethereum, Ripple. The dependence of the economic development level of the country and the degree of cryptocurrency implementation is revealed. The world legislative experience in the field of regulation of the cryptocurrency is researched. The possibility of its application in the Ukrainian legislation by the cryptocurrency legalization and minimization of risks in the process of use are studied. Prospects for the spread and further development of cryptocurrencies in Ukraine and in the world are considered. It is noted that providing the improvement of monetary technology, its proper regulation and improvement of infrastructure, this financial instrument will occupy an important place in people's daily life.
In den vergangen Jahren haben Corwd-Sensing-Anwendungen immer mehr an Relevanz gewonnen. Mit der Zunahme von mobilen Geräten nahm auch die Verwendung dieser als Sensoren zur Datenerhebung zu. In dieser Arbeit betrachten wir hierbei die Nutzung eines solchen Systems zur Verfolgung mobiler Objekte. Smart-Contracts bieten seit wenigen Jahren die Möglichkeit, dezentral auf einer Blockchain Anwendungen zu implementieren, welche nicht auf einen einzelnen Server angewiesen sind. Smart-Contracts sind transparent und können außerhalb der ersichtlichen, implementierten Möglichkeiten nicht manipuliert werden. Mobile-Target-Tracking-Anwendungen selbst sind keine Neuheit mehr, wohl aber die dezentrale Ausführung dieser auf einer Blockchain. Im Rahmen dieser Arbeit wurde eine Mobile-Target-Tracking-Anwendung implementiert, welche mithilfe von Crowd-Sensing ein Objekt sucht. Die erfassten Daten werden an den Smart-Contract in der Ethereum-Blockchain gesendet, dort gespeichert und nach Erreichen bestimmter Kriterien ausgewertet. Die korrekten Meldungen sollen vom Smart-Contract mit einem Ether-Betrag belohnt werden. Dazu werden in dieser Arbeit verschiedene Algorithmen zum Finden einer konsistenten Menge von Sichtungen diskutiert. Die Herausforderungen der Implementierung und die Evaluation der entstandenen Smart-Contracts werden in dieser Arbeit vorgestellt.
This article represents the chronology of the use of digital currency by professional participants in the US financial market. There are indicated main participants of the digital currency market using this asset for investment and speculative purposes. There are described their actions on the digital currency market. There are analyzed possible stages of the development of the digital currency market. Digital currency Bitcoin and Ethereum are represented. Attention is paid to the innovations of the JP Morgan Chase Corporation, the Facebook Corporation. There are described new exchange assets introduced by Cboe, CME Group, and Bakkt.
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Economic and Technological Developments in Russia
Economic, Social, and Public Health Issues in Russia and Globally