As a computer programmer, a smart contract encapsulates the contractual features of the partiesâ transactions through code. Some blockchain technology platforms, such as Hyperledger Fabric, IBM Blockchain and Ethereum, currently allow smart contracts. Smart contracts on these platforms are kept on the blockchain and are not under the control of any party involved. They canât be tampered with after theyâve been digitally signed and placed on the blockchain. The use of smart contracts in blockchains is critical. It is the authorsâ primary goal with this research to provide an alternative to standard contracts by allowing users to modify data stored in the chain. Methodology for designing smart contracts is presented in this article, along with an example of how it has used modifications to the data stored in the chain. In this article, we present a methodology for the design of smart contracts and we also illustrate its application with a case study.
An electronic medical record (EMR) is the digital medical data of a patient, and they are healthcare system's most valuable asset. In this paper, we introduce a decentralized network using blockchain technology and smart contracts as a solution to manage and secure medical records storing, and transactions between medical healthcare providers. Ethereum blockchain is employed to build the blockchain. Solidity object-oriented language was utilized to implement smart contracts to digitally facilitate and verify transactions across the network (creating records, access requests, permitting access, revoking access, rejecting access). This will mitigate prevailing issues of current systems and enhance their performance, since current EMRs are stored on a centralized database, which cannot guarantee data integrity and security, consequently making them susceptible to malicious attacks. Our proposed system approach is of vital importance considering that healthcare providers depend on various tests in making a decision about a patient's diagnosis, and the respective plan of treatment they will go through. These tests are not shared with other providers, while data is scattered on various systems, as a consequence of these ensuing scenarios, patients suffer of the resulting care provided. Moreover, blockchain can meliorate the motley serious challenges caused by future use of IoT devices that provide real-time data from patients. Therefore, integrating the two technologies will produce decentralized IoT based healthcare systems.
Leo Eichhorn, Tanya Shreedhar, Aleksandr Zavodovski, Nitinder Mohan
Edge computing has received significant attention from both academic and industrial research circles. The paradigm aims to decentralize the existing cloud infrastructure by incorporating resources co-located alongside its client. Researchers have also proposed solutions for a fully decentralized crowdsourced compute paradigm enabled by Distributed Ledger Technologies (DLTs). This paper investigates the rationale behind DLTs over crowdsourced resource marketplaces to support the requirements of latency-critical applications targeted by edge computing. We develop a fully configurable NEtworked Blockchain emULAtor, or NEBULA, to scrutinize the internal performance bottlenecks of DLTs. We evaluate two blockchain categories - proof-based (popularly used in Bitcoin, Ethereum) and hybrid consensus and find that the enabling factor of DLTs -scale - is also its primary latency contributor. We show that, in reality, the latency overheads due to DLT operation far exceed the operational requirements of edge applications.
On an Ethereum node, txpool (a.k.a. mempool) is a buffer storing unconfirmed transactions and controls what downstream services can see, such as mining and transaction propagation. This work presents the first security study on Ethereum txpool designs.
Luc Gerrits, Cyril Naves Samuel, Roland Kromes, François Verdier · 6 authors
Private or consortium blockchain networks have fewer verified participants and offer better throughput and transaction efficiency than public networks. However, as more and more blockchain consensuses are designed for private or consortium networks, their performances are often estimated without a practical use case implementation. In our use case, participants do not have to trust each other but still work together to build an ecosystem where users control their data and information. This paper analyzes the performance (transaction throughput, rejections, node participants) of Byzantine Fault Tolerant Consensus (BFT) using two blockchains: Hyperledger Sawtooth and Ethereum.
This research is the first attempt to customize a trading system that is based on second order stochastic dominance (SSD) to five known cryptocurrenciesâ daily data: Bitcoin, Ethereum, XRP, Binance Coin, and Cardano. Results show that our system can predict price trends of cryptocurrencies, trade them profitably, and in most cases outperform the buy and hold (B&H) simple strategy. Our systemâs best performance was achieved trading XRP, Binance Coin, Ethereum, and Bitcoin. Although our system has also generated a positive net profit (NP) for Cardano, it failed to outperform the B&H strategy. For all currencies, the system better predicted long trends than short trends.
Mounzer Saijare, Ä°Ìhsan Tolga Medeni, Tunç D. Medeni, Mehmet Serdar GĂŒzel
Ethereum databases with their huge security and integrity can provide perfect mechanism for storing and sharing the data of the highly important projects. Qualitative and quantitative research methods were used in this paper to design software for Ethereum databases. Also, these methods were used to examine how and how much features can be added to the software. Designing the software considered the barriers and the limitations of Solidity smart contracts programming language and Ethereum blockchain platform. The achieved software can make any Ethereum database with parent-child relationships in between the tables. More professional features will be added in future research as soon as possible. The study used survey method to discuss recommended applications for the software integration with another software for ESRI digital maps programming. The recommended applications are the real estate business full automation and the transparent environmental management to protect the Mediterranean Sea from the pollution. However, most parts related to Ethereum databases software are covered. But to keep this paper in reasonable size, only the survey is included for the parts related to the software recommended applications with the digital maps software.
Fulvia Pennoni, Francesco Bartolucci, Gianfranco Forte, Ferdinando M. Ametrano
Abstract A hidden Markov model is proposed for the analysis of timeâseries of daily logâreturns of the last 4 years of Bitcoin, Ethereum, Ripple, Litecoin, and Bitcoin Cash. These logâreturns are assumed to have a multivariate Gaussian distribution conditionally on a latent Markov process having a finite number of regimes or states. The hidden regimes represent different market phases identified through distinct vectors of expected values and varianceâcovariance matrices of the logâreturns, so that they also differ in terms of volatility. Maximumâlikelihood estimation of the model parameters is carried out by the expectationâmaximisation algorithm, and regimes are singularly predicted for every time occasion according to the maximumâaâposteriori rule. Results show three positive and three negative phases of the market. In the most recent period, an increasing tendency towards positive regimes is also predicted. A rather heterogeneous correlation structure is estimated, and evidence of structural medium term trend in the correlation of Bitcoin with the other cryptocurrencies is detected.
Trust and transparency are the basics of any nonprofit or non-financial organizations. It is believed that charities that are accountable and transparent are more likely to act with integrity because they want donors to know that they’re trustworthy. Keeping in mind the fact of transparency and integrity, block chain is the state-of-the-art technology which has given solution to the problem mentioned before. In this paper the use of proof of authority as a consensus protocol in Ethereum blockchain platform is proposed. A detailed tutorial of blockchain mechanism along with the detailed comparison of three main platforms bitcoin, Ethereum and Hyperledger in which blockchain has been explored a lot. Furthermore, there is a detail overview of how blockchain has flourished itself in various fields of non-profit and non-financial organizations. Finally, we have proposed an economical model along with the framework which uses less computational power.
Globally, disruptive technologies play a vital role in ordinary peopleâs lives to technocrats, small-scale industry to multinational companies, and private sectors to government sectors. Providing security and privacy preservation of the sensitive data in various applications related to a bank, healthcare sectors, etc., are becoming significant issues with advanced technologies. Unauthorized persons and also attackers get benefits from the features. Permissionless and open access features will become advantages to the cyber attackers to crack the data. These issues will be resolved by adopting some knowledge management systems (KMSs) like blockchain technology, and Artificial Intelligence. Therefore, this chapter proposed a web-based knowledge management decentralized application using blockchain technology in healthcare sectors. Especially in the healthcare centers, peopleâs sensitive personal data such as name, address, financial details, and cause maintain as records. Cyber attackers treat the medical records as treasure. Advanced featured technology, blockchain incorporation with web-based applications can reduce the attacks like ransomware, phishing, Brute force, steals credentials, and Man in the middle attack. The technologyâs main inherited features are distributed, immutable, transparency, security, and peer-to-peer network communication. This hybrid approach, a combination of Web 3.0 and blockchain technology, increases the privacy and preservation of official medical documents issued by healthcare centers. This chapter illustrated the process of a proposed decentralized application using Ethereum-based Blockchain with Metamask wallet. This workâs main strength is the proposed application deployed results over an ethereum blockchain platform on test RPC, which are laps in the maximum related literature survey works currently available. Furthermore, presented comprehensively about the deployment cost of the application operations in terms of smart contracts and execution time for uploading credential requests.
Blockchain technologies have been boosting the development of data-driven decentralized services in a wide range of fields. However, with the spirit of full transparency, many public blockchains expose all types of data to the public such as Ethereum. Besides, the on-chain persistence of large data is significantly expensive technically and economically. These issues lead to the difficulty of sharing fairly large private data while preserving attractive properties of public blockchains. Although direct encryption for on-chain data persistence can introduce confidentiality, new challenges such as key sharing, access control, and legal rights proving are still open. Meanwhile, cross-chain collaboration still requires secure and effective protocols, though decentralized storage systems such as IPFS bring the possibility for fairly large data persistence. In this paper, we propose Sunspot, a decentralized framework for privacy-preserving data sharing with access control on transparent public blockchains, to solve these issues. We also show the practicality and applicability of Sunspot by MyPub, a decentralized privacy-preserving publishing platform based on Sunspot. Furthermore, we evaluate the security, privacy, and performance of Sunspot through theoretical analysis and experiments.
In this paper, I examine how social media affects cryptocurrencies and more traditional stocks. I use data on Twitter posts in combination with daily stock prices to estimate the causal effect of a tweet on stock and coin prices. To do this, I use a difference-indifference regression with index funds as my control group, which allows me to capture general market trends that coins and stocks would follow if not for intervention. I find that tweets have a significant impact on cryptocurrencies that last up to three days after the post. The increase in coin prices is driven by tweets from Tyler Winklevoss and tweets about Tezos and Ethereum specifically. Meanwhile, Twitter posts have no impact on more traditional stocks. These results suggest that social media can provide the public with valuable information in real time for fast moving and volatile crypto assets, while their effects on more stable and institutionalized traditional stocks are more muted.
Kevin Tjiam, Rui Wang, Huanhuan Chen, Kaitai Liang
Smart contracts on Ethereum enable billions of dollars to be transacted in a decentralized, transparent and trustless environment. However, adversaries lie await in the Dark Forest, waiting to exploit any and all smart contract vulnerabilities in order to extract profits from unsuspecting victims in this new financial system. As the blockchain space moves at a breakneck pace, exploits on smart contract vulnerabilities rapidly evolve, and existing research quickly becomes obsolete. It is imperative that smart contract developers stay up to date on the current most damaging vulnerabilities and countermeasures to ensure the security of users' funds, and to collectively ensure the future of Ethereum as a financial settlement layer. This research work focuses on two smart contract vulnerabilities: transaction-ordering dependency and oracle manipulation. Combined, these two vulnerabilities have been exploited to extract hundreds of millions of dollars from smart contracts in the past year (2020-2021). For each of them, this paper presents: (1) a literary survey from recent (as of 2021) formal and informal sources; (2) a reproducible experiment as code demonstrating the vulnerability and, where applicable, countermeasures to mitigate the vulnerability; and (3) analysis and discussion on proposed countermeasures. To conclude, strengths, weaknesses and trade-offs of these countermeasures are summarised, inspiring directions for future research.
In blockchains such as Bitcoin and Ethereum, users compete in a transaction fee auction to get their transactions confirmed in the next block. A line of recent works set forth the desiderata for a "dream" transaction fee mechanism (TFM), and explored whether such a mechanism existed. A dream TFM should satisfy 1) user incentive compatibility (UIC), i.e., truthful bidding should be a user's dominant strategy; 2) miner incentive compatibility (MIC), i.e., the miner's dominant strategy is to faithfully implement the prescribed mechanism; and 3) miner-user side contract proofness (SCP), i.e., no coalition of the miner and one or more user(s) can increase their joint utility by deviating from the honest behavior. The weakest form of SCP is called 1-SCP, where we only aim to provide resilience against the collusion of the miner and a single user. Sadly, despite the various attempts, to the best of knowledge, no existing mechanism can satisfy all three properties in all situations. Since the TFM departs from classical mechanism design in modeling and assumptions, to date, our understanding of the design space is relatively little. In this paper, we further unravel the mathematical structure of transaction fee mechanism design by proving the following results: - Can we have a dream TFM? - Rethinking the incentive compatibility notions. - Do the new design elements make a difference?
Cloud computing provides a feasible solution to data outsourcing, and hence forming a cloud-based data market, where data users buy data from owners through querying cloud servers. However, it also incurs new privacy and security problems, as data is under a centralized third-party instead of the data ownerâs direct control. Existing data markets are also questioned on their inflexible and opaque pricing, where the value of data ownership and the cost of query searches are mixed. In this paper, we consider blockchain-based storage as a better choice to ensure safe data outsourcing since data is spread out across many data points. We propose an Ethereum-based data market that provides distributed storage and correct remote data search. We design a new pricing model, where each query will be charged by two parties: owner (paid for providing his data) and miner (rewarded by performing query searches). We study a new cooperative search scheme through a proxy to reduce cost on the user side. Given that each user query is charged based on its number of keywords, then a cooperative search can reduce user-side cost by combining multiple queries into a group so that overlapped keywords will only be charged for one time. To ensure user QoE, a combined query should not be significantly larger than any of its original queries in terms of the number of keywords. The total price is based on the total number of keywords in all groups. Since it is a cooperative model with shared resources, we also study various incentive properties on the user side, yielding a cost sharing mechanism to split joint cost in a truth-revealing and fair manner. We further extend our market with a set of substitute data owners and propose a double auction mechanism to match users and owners based on their requirements. Experiments have been conducted on real query trace to demonstrate the effectiveness of our proposed scheme.
This paper investigates the problem of distributed storage of electronic documents (both metadata and files) in decentralized blockchain-based b2b systems (DApps). The need to reduce the cost of implementing such systems and the insufficient elaboration of the issue of storing big data in DLT are considered. An approach for building such systems is proposed, which allows optimizing the size of the required storage (by using Erasure coding) and simultaneously providing secure data storage in geographically distributed systems of a company, or within a consortium of companies. The novelty of this solution is that we are the first who combine enterprise DLT with distributed file storage, in which the availability of files is controlled. The results of our experiment demonstrate that the speed of the described DApp is comparable to known b2c torrent projects, and subsequently justify the choice of Hyperledger Fabric and Ethereum Enterprise for its use. Obtained test results show that public blockchain networks are not suitable for creating such a b2b system. The proposed system solves the main challenges of distributed data storage by grouping data into clusters and managing them with a load balancer, while preventing data tempering using a blockchain network. The considered DApps storage methodology easily scales horizontally in terms of distributed file storage and can be deployed on cloud computing technologies, while minimizing the required storage space. We compare this approach with known methods of file storage in distributed systems, including central storage, torrents, IPFS, and Storj. The reliability of this approach is calculated and the result is compared to traditional solutions based on full backup.
Md. Zıa Ur Rahman, Sala Surekha, Krishna Prasad Satamraju, Shafi Shahsavar Mirza · 5 authors
Healthcare is one of the largest domains across the globe both in terms of employment and income generation. It is continuously evolving and exploiting new technological dimensions to incorporate innovations for providing universal health coverage. Sharing of data collected by various sensors deployed at the patientâs end is a growing solicitude in healthcare as the privacy of the personal healthcare data is of paramount importance. In this paper, a blockchain based healthcare framework is proposed to address the problems related to the sensor-based patient vital body parameters collection, monitoring, secured data storage and sharing among different stakeholders. This framework uses Internet of Medical Things (IoMT) devices interfaced with MAX30205 (human body temperature), and a blood pressure including heart-rate measuring device to collect the patient vital parameters. A Markov state chain is modeled to monitor the patient medical states through various phases during the treatment and monitoring process. Application layer protocols MQTT, CoAP, and AMQP are evaluated for latency and packet loss during data transfers. Ethereum permissioned blockchain is used to deploy the proposed model. Smart contracts provide access control only to authorized users. A comparative analysis is provided in the end to highlight the merits of the proposed model over the existing similar methods. Due to the parallelism and use of blockchain, the system reports 80% improvement in terms of nodes and transaction scalability compared to the existing systems.
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In the last decade patient management systems or eHealth has gained huge attraction with researchers. eHealth spans from the remote access of medical records to actual data exchange of remote patient's data of their body sensors. In this paper we propose a decentralized application model that uses Ethereum private Blockchain, Inter-Planetary File System (IPFS), and associated web technologies that aim to help healthcare providers, policymakers, and research organizations in Nepal. It presents the outcome of a survey conducted among the general public and a focus group discussion with medical doctors in relation to their current practices and limitations in storing and sharing patients' medical histories for examinations or treatments. The paper concludes with why blockchain technologies can be a better option for public and private healthcare institutions as well as medical practitioners to store and share patient records to deliver timely and quality healthcare services in a resource-poor country like Nepal.
Access control is essential in computer security systems to regulate the access to critical or valuable resources. Conventional access control models mainly rely on a centralized and trusted server to mediate each attempted access from client to resources, which face serious challenges of single point of failure and lack of transparency. In this brief, we propose a smart contract-based access control framework, which enables the owner to achieve resource access control in a reliable, auditable and scalable way. An access control contract is deployed on blockchain to manage attribute-based access policies of resources flexibly and make access decisions for clients credibly. A set of attributes is distributed to the clients through off-chain signatures signed by the owner to determine their privileges, without consuming the expensive on-chain storage space. Finally, we implement an experimental prototype on Ethereum test network and perform extensive experimental and theoretical analysis to evaluate its scalability and efficiency.
Because the existing wind turbine safety is limited by the traditional centralised management, it faces many security risks. Therefore, the future wind turbine management and control scheme is developing towards distributed security and high performance. Relying on Ethereum block technology to build smart contracts can help solve the security protection problems of network authority control and management in wind power energy systems. First, based on the analysis of wind power network security management needs, establish a mathematical model of security indicators for the control centre and subordinate nodes, respectively, when the permissions are out of control; second, based on the Ethereum smart contract release platform, according to the mathematical model of security indicators run wind power contract management (WPCM), predict the results of out-of-control simulation, and compare with the communication parameters of a typical wind farm in Northwest Europe. Studies have shown that the established wind power energy network security management plan has the characteristics of high security and good robustness, and the system processing speed is fast, which meets the offshore wind farm communication standard.