<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>
Blockchain is a decentralized ledger technology, and it is the technology underlying Bitcoin and Ethereum. The interest in blockchain has been increasing since its emergence. Hyperledger Fabric is one of the permissioned blockchain frameworks. One of the characteristics of Hyperledger Fabric is it utilizes general-purpose programming languages, e.g., Go, Node.js, and Java, to implement smart contracts (called chaincode in Hyperledger Fabric). The advantages of utilizing these languages are already known to potential developers, and development tools might already exist. However, one of the disadvantages is that these languages were not originally designed for writing smart contracts. Hence, there may be risks that developers do not need to consider when using specific languages such as Solidity of Ethereum. Furthermore, even though development tools exist, how many risks are covered by the tools is an open question. In this paper, we focus on Go language and the tools. First, we surveyed what kind of risks are associated with chaincodes are developed using Go language and observed there are 14 potential risks. Then, we investigated how many risks can be covered by Go tools, e.g., golint and gosec, and a vulnerability detection tool for chaincodes called Chaincode Scanner. From our results, we observed that some risks are not covered by the existing tools. Hence, we develop a detection tool to cover risks by static analysis. Finally, in this paper, we describe how to find the risks with our tool and evaluate the usefulness.
Emergency service call for public service providers has become an important role for smart home applications in order to support safety and security in the household building. Blockchain has been a promising solution with cryptography and incentive distributed mechanisms to support the verification, execution and recording of transactions between untrusted parties. In this paper, we present a Smart Home System (SHS) based on Ethereum with smart contract infrastructure for handling an emergency service sending from SHS to Home Service Providers (HSP) when there are unusual environmental conditions. Our SHS testbed consists of three domains: (1) Smart Home Sensor Manager (SM) or IoT devices to gather environmental sensor data and send an emergency call to HSP, (2) Home Service Provider (HSP) system deployed with Ethereum Virtual Machine (EVM) and smart contract, and (3) decentralize Meteor framework to interface between Ethereum and web based applications for homeowners (HO) and HSP staffs. To achieve homeowner privacy and security, we enable digital signature coupling with InterPlanetary File System (IPFS) for handling the emergency call from SM to HSP and One Time Passcode (OTP) produced by HSP for HSP staffs to verify themselves for further access control when they go to service homeowner's house. Each smart contract transaction in solidity is described. Finally, security and privacy issues for our proposed work are discussed.
In Ethereum, many accounts and funds have been managed by smart contracts, thereby making them easy to be targeted. Due to the persistence characteristic of blockchain, revising a deployed smart contract is almost impossible. Both realities heighten the risks of managing funds and thus increase the demand for conducting sufficient testing to Ethereum Smart Contracts (ESC). Different from the conventional software, ESC is a gas-driven program, where developers must charge gases for deploying and testing it. Therefore, it is important to provide a cost-effective yet representative test suite, where its representativeness can be typically measured by its branch coverage. In this paper, we deem the problem of ESC test generation as a Pareto minimization problem, and three objectives, minimizing (1) uncovered branch coverage, (2) time cost, and (3) gas cost are considered. Then, we propose a random based and an NSGA-II based multi-objective approach to seek cost-effective test-suites. Our empirical study on a set of smart contracts in eight of the most widely used Ethereum Decentralized Applications (DApps) verified that the proposed approaches could significantly reduce the gas cost as well as the time cost while retaining the ability to cover branches.
Attacks on transactions of Ethereum could be dangerous because they could lead to a big loss of money. There are many tools detecting vulnerabilities in smart contracts trying to avoid potential attacks. However, we found that there are still many missed vulnerabilities in contracts. Motivated by this, we propose a methodology to reinforce EVM to stop dangerous transactions in real time even when the smart contract contains vulnerabilities. Basically, the methodology consists of three steps: monitoring strategy definition, opcode-structure maintenance and EVM instrumentation. Monitoring strategy definition refers to the specific rule to test whether there is a dangerous operation during transaction execution. Opcode-structure maintenance is to maintain a structure to store the rule related opcodes and analyze it before an operation execution. EVM instrumentation inserts the monitoring strategy, interrupting mechanism and the opcode-structure operations in EVM source code. For evaluation, we implement EVM*on js-evm, a widely-used EVM platform written in javascript. We collect 10 contracts online with known bugs and use each contract to execute a dangerous transaction, all of them have been interrupted by our reinforced EVM*, while the original EVM permits all attack transactions. For the time overhead, the reinforced EVM*is slower than the original one by 20-30%, which is tolerable for the financial critical applications.
Notice of Violation of IEEE Publication Principles"AQUACHAIN -Water Supply-Chain Management using Distributed Ledger Technology"by Nibi Maouriyan, A.G. Achudh Krishnain the Proceedings of the 3rd International Conference on Computing and Communications Technologies (ICCCT), 2019, pp. 204-207After careful and considered review of the content and authorship of this paper by a duly constituted expert committee, this paper has been found to be in violation of IEEE’s Publication Principles.This paper is a duplication of the original text from the paper cited below. The original text was copied without attribution (including appropriate references to the original author(s) and/or paper title) and without permission.Due to the nature of this violation, reasonable effort should be made to remove all past references to this paper, and future references should be made to the following article:"Blockchain-based Traceability in Agri-Food Supply Chain Management: A Practical Implementation"by Miguel Pincheira Caro, Muhammad Salek Ali, Massimo Vecchio, Raffaele Giaffredain the Proceedings of the IoT Vertical and Topical Summit on Agriculture - Tuscany (IOT Tuscany), 2018Water shortage is fast becoming one of the biggest crises of this century. The recent, exponential rise in adoption of the most disparate Internet of Things (IoT) devices and technologies has reached also Water supply chains, drumming up substantial research and innovation interest towards developing reliable, auditable and transparent traceability systems. Current IoT-based traceability and provenance systems for water supply chains are built on top of centralized infrastructures and this leaves room for unsolved issues and major concerns, including data integrity, tampering and single points of failure. Blockchains, the distributed ledger technology underpinning cryptocurrencies such as Bitcoin, represent a new and innovative technological approach to realizing decentralized trustless systems. This will also eliminate corruption due to unmaintained record of sources. Indeed, the inherent properties of this digital technology provide fault-tolerance, immutability, transparency and full traceability of the stored transaction records, as well as coherent digital representations of physical assets and autonomous transaction executions. This paper presents Aqua-chain, a fully decentralized, blockchain-based traceability solution for Water supply chain management, able to seamless integrate IoT devices producing and consuming digital data along the chain. To effectively assess Aqua-chain, first, we defined a classical use-case within the given vertical domain, namely from-supplier-to-buyer. Then, we developed and deployed such use-case, achieving traceability using blockchain implementation, Ethereum. Finally, we evaluated and compared the performance deployments, in terms of latency, CPU, and network usage, also highlighting its main pros and cons.
This thesis investigates diversification benefits of Bitcoin and Ethereum. Technological innovation that made them possible, is interesting but for investors hard to grasp. The more important question is whether they should buy the digital currency or avoid it. We analyze Bitcoin and Ethereum from point of view of an investor within compatible with mean-variance (and non-mean-variance respectively) framework. Both cryptoassets are alternately added to base portfolio consisting of global indices representing American, European and Asian markets. Statistically rigorous tests suggest that Bitcoin yields ad- ded value to investors with utility function consistent with mean-variance setting. Same holds for for investors with preferences described by exponential and power utility func- tion. Ethereum shows similar results with exception of exponential utility. Performance benefits of both assets are preserved in the out-of-sample setting as size of test window reaches 28 weeks and increases. In the case of shorter test window, base assets show similar or slightly superior performance. Optimal allocation in out-of-sample framework is found by direct utility maximization with gradient based method. Keywords Bitcoin, Ethereum, digital currency, investment portfolio, diversification
Same story for Ethereum as well as overall crypto opened with gaps today and some covered it already (Litecoin for example). After price opened with a $31 gap upwards, price consolidated in blue area and started making a steady drop towards the opening l
Since Bitcoin was introduced in 2008, blockchains have established as a tool for speculation as well as decentralized applications. In 2014, Ethereum, a so-called second-generation blockchain, introduced the concept of smart contracts, which allows the decentralization and disintermediation of a wide range of use cases and industries. In the context of financial instruments or securities, smart contracts allow increased transparency, liquidity, availability, and auditability, while significantly reducing the barrier to entry for potential investors. In recent months, numerous projects and standard proposals have aimed to facilitate the tokenization of securities. However, regulatory compliance imposes a major challenge for security token platforms. Current realizations of legally required user verifications lack scalability, flexibility, and reusability. Furthermore, potential investors are confronted with tedious redundant processes to disclose private data per investment opportunity. We address these challenges by proposing a smart contract architecture that generally solves legal compliance. Immutable logic, the upgradability of compliances, as well as structuring evaluation logic in hierarchies allow the realization of arbitrary regulatory clauses. Our design addresses both the primary and secondary market, and can easily be extended, e.g. to allow secondary offerings or legal enforcement. Furthermore, we envision a network of trust realized via identity management on the blockchain. Hereby, conventions between platforms, regulators, and exchanges fully automate legal checks throughout atomic transactions on the Ethereum blockchain. Furthermore, we use so-called oracles to bridge blockchain-based logic with regulatory definitions, e.g. investment limits in Euro. We compare our proposal to existing implementations and extensively discuss design decisions. Furthermore, we evaluate our proposal with exemplary use cases. Specifically, we fully implement a fictive compliance to demonstrate general concepts, as well as evaluate real-world challenges derived from legal frameworks. Our work aims to complement existing work related to security token in order to accelerate the adoption of asset tokenization.
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
The Google Trends 1 search analysis service and the Telegram 2 messaging platform are investigated to determine their respective relationships to cryptocurrency price behaviour. It is shown that, in contrast to earlier findings, the relationship between cryptocurrency price movements and internet search volumes obtained from Google Trends is no longer consistently positive, with strong negative correlations detected for Bitcoin and Ethereum during June 2018. Sentiment extracted from cryptocurrency investment groups on Telegram is found to be positively correlated to Bitcoin and Ethereum price movements, particularly during periods of elevated volatility. The number of messages posted on a Bitcoin-themed Telegram group is found to be an indicator of Bitcoin price action in the subsequent week. A long shortterm memory (LSTM) recurrent neural network is developed to predict the direction of cryptocurrency prices using data obtained from Google Trends and Telegram. It is shown that Telegram data is a better predictor of the direction of the Bitcoin market than Google Trends. The converse is true for Ethereum. The LSTM model produces the most accurate results when predicting price movements over a one-week period.
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.