Blockchain Papers

Steven Farrugia, Joshua Ellul, George Azzopardi

No abstract is available for this record.

Ajaya Mandal, Prakriti Dumaru, Sagar Bhandari, Shreeti Shrestha · 5 authors

With a view to overcome the shortcomings of traditional Electronic Health Record (EHR) system so as to assure the interoperability by providing open access to sensitive health data, while still preserving personal data privacy, anonymity and avoiding data misuse, Decentralized Electronic Health Record System was developed. The aforementioned issue concerning traditional EHR system can be addressed by implication of emerging technology of the era namely Block chain, together with Inter Planetary File System (IPFS) which enables data sharing in decentralized and transactional fashion, thereby maintaining delicate balance between privacy and accessibility of electronic health records. A block chain based EHR system has been built for secure, efficient and interoperable access to medical records by both patients and doctors while preserving privacy of the sensitive patient’s information. Patients can easily and comprehensively access to their medical records across providers and treatment sites using unique properties of block chain and decentralized storage. A separate portal for both the patients and doctors has been built enabling the smart contracts to handle further interaction between doctors and patients. So, in this system, it is demonstrated how principles of decentralization and block chain architectures could contribute to EHR system using Ethereum smart contracts and IPFS to orchestrate a suitable system governing the medical record access while providing patients with comprehensive record review along with consideration for audit ability and data sharing.

Raj Kumar Shrestha, Rajiv Kumar Sah, Sabin Shrestha, Shailja Sarawagi · 5 authors

National elections are a big deal which has a major role in the development and progress of a country. The security of an election is in fact the matter of national security. Current voting systems in the context of Nepal and other parts of the world are still traditional and insecure. From the dawn of democracy, elections are still based on pen and papers. While there are new electronic voting machines, these systems have a high risk of rigging and are prone to failure, crashes, and attacks from intruders. The stated problems can be addressed through the implementation of new technology namely Blockchain for a transparent and reliable voting process. A blockchain based voting platform has been built to make the voting process digital, secure, reliable and intuitive. The votes casted by voters are stored in the blockchain, thus making it immutable and secure. The system can be scaled based on the requirements of an election. Voters can login to the system with the help of encrypted identification. This encrypted identification will lead to secure voting process. A separate portal for both voters and the election commission reduces the election hassle and time. So, in this system, it is demonstrated how the use of blockchain platform could contribute to modern elections using Ethereum, smart contracts and distributed systems to provide voters with secure, transparent and reliable voting platform.

Yuheng Huang, Haoyu Wang, Lei Wu, Gareth Tyson · 9 authors

EOSIO has become one of the most popular blockchain platforms since its mainnet launch in June 2018. In contrast to the traditional PoW-based systems (e.g., Bitcoin and Ethereum), which are limited by low throughput, EOSIO is the first high throughput Delegated Proof of Stake system that has been widely adopted by many applications. Although EOSIO has millions of accounts and billions of transactions, little is known about its ecosystem, especially related to security and fraud. In this paper, we perform a large-scale measurement study of the EOSIO blockchain and its associated DApps. We gather a large-scale dataset of EOSIO and characterize activities including money transfers, account creation and contract invocation. Using our insights, we then develop techniques to automatically detect bots and fraudulent activity. We discover thousands of bot accounts (over 30\% of the accounts in the platform) and a number of real-world attacks (301 attack accounts). By the time of our study, 80 attack accounts we identified have been confirmed by DApp teams, causing 828,824 EOS tokens losses (roughly 2.6 million US\$) in total.

Simon Dyson, William J. Buchanan, Liam Bell

No abstract is available for this record.

Tasos Bakogiannis, Ioannis Mytilinis, Katerina Doka, Georgios Goumas

Cloud computing offerings traditionally originate from a handful of large and well established providers, which monopolize the market, preventing small players and individuals from having a share. As a result, the few, blindly and perforce trusted entities define the prices and manage to gain a significant competitive advantage by exploiting the knowledge derived by users’ data and computations. To tackle this monopoly and empower the democratization and full decentralization of the cloud computing market, we present CloudAgora, a platform that enables any potential resource provider, ranging from individuals to large companies, to monetize idle resources competing on equal terms, and allows any cloud consumer to enjoy access to low-cost storage and computation without having to trust any central authority. The key enabler of the platform is Blockchain technology, which is used to record commitment policies through the use of smart contracts, publicly verify off-chain services, both storage and computation related, and trigger automatic micropayments. On one hand, cloud consumers have the chance to request storage or compute resources, upload data, and outsource task processing over remote, fully distributed infrastructures. Although such infrastructures cannot be a priori trusted, CloudAgora offers mechanisms to ensure the verifiable validity of the outsourced storage and computation, discourage potential providers from behaving maliciously, and incentivize participants to play fair. On the other hand, providers are able to participate in auctions, placing bids for storage or computation tasks, serve requests, and offer validity proofs upon request. Our prototype is built as a Dapp on top of Ethereum and is available as an open source project.

Hartwig Mayer, Ismael Bejarano, Daniel Fernandez, Gustavo Ajzenman · 8 authors

BatPay is a proxy scaling solution for the transfer of ERC20 tokens. It is suitable for micropayments in one-to-many and few-to-many scenarios, including digital markets and the distribution of rewards and dividends. In BatPay, many similar operations are bundled together into a single transaction in order to optimize gas consumption on the Ethereum blockchain. In addition, some costly verifications are replaced by a challenge game, pushing most of the computing cost off-chain. This results in a gas reduction of the transfer costs of three orders of magnitude, achieving around 1700 transactions per second on the Ethereum blockchain. Furthermore, it includes many relevant features, like meta-transactions for end-user operation without ether, and key-locked payments for atomic exchange of digital goods.

Pooja Gupta, Volkan Dedeoglu, Kamran Najeebullah, Salil S. Kanhere · 5 authors

Personal IoT data is a new economic asset that individuals can trade to generate revenue on the emerging data marketplaces. Typically, marketplaces are centralized systems that raise concerns of privacy, single point of failure, little transparency and involve trusted intermediaries to be fair. Furthermore, the battery-operated IoT devices limit the amount of IoT data to be traded in real-time that affects buyer/seller satisfaction and hence, impacting the sustainability and usability of such a marketplace. This work proposes to utilize blockchain technology to realize a trusted and transparent decentralized marketplace for contract compliance for trading IoT data streams generated by battery-operated IoT devices in real-time. The contribution of this paper is two-fold: (1) we propose an autonomous blockchain-based marketplace equipped with essential functionalities such as agreement framework, pricing model and rating mechanism to create an effective marketplace framework without involving a mediator, (2) we propose a mechanism for selection and allocation of buyers' demands on seller's devices under quality and battery constraints. We present a proof-of-concept implementation in Ethereum to demonstrate the feasibility of the framework. We investigated the impact of buyer's demand on the battery drainage of the IoT devices under different scenarios through extensive simulations. Our results show that this approach is viable and benefits the seller and buyer for creating a sustainable marketplace model for trading IoT data in real-time from battery-powered IoT devices.

John Kolb, Moustafa AbdelBaky, Randy H. Katz, David Culler

Blockchains are a topic of immense interest in academia and industry, but their true nature is often obscured by marketing and hype. In this tutorial, we explain the fundamental elements of blockchains. We discuss their ability to achieve availability, consistency, and data integrity as well as their inherent limitations. Using Ethereum as a case study, we describe the inner workings of blockchains in detail before comparing blockchains to traditional distributed systems. In the second part of our tutorial, we discuss the major challenges facing blockchains and summarize ongoing research and commercial offerings that seek to address these challenges.

Laura A. Franke, Marco Schletz, Søren Salomo

This paper examines the benefits and constraints of applying blockchain technology for the Paris Agreement carbon market mechanism and develops a list of technical requirements and soft factors as selection criteria to test the feasibility of two different blockchain platforms. The carbon market mechanism, as outlined in Article 6.2 of the Paris Agreement, can accelerate climate action by enabling cooperation between national Parties. However, in the past, carbon markets were limited by several constraints. Our research investigates these constraints and translates them into selection criteria to design a blockchain platform to overcome these past limitations. The developed selection criteria and assumptions developed in this paper provide an orientation for blockchain assessments. Using the selection criteria, we examine the feasibility of two distinct blockchains, Ethereum and Hyperledger Fabric, for the specific use case of Article 6.2. These two blockchain systems represent contrary forms of design and governance; Ethereum constitutes a public and permissionless blockchain governance system, while Hyperledger Fabric represents a private and permissioned governance system. Our results show that both blockchain systems can address present carbon market constraints by enhancing market transparency, increasing process automation, and preventing double counting. The final selection and blockchain system implementation will first be possible, when the Article 6 negotiations are concluded, and governance preferences of national Parties are established. Our paper informs about the viability of different blockchain systems, offers insights into governance options, and provides a valuable framework for a concrete blockchain selection in the future.

Tianyu Sun, Wensheng Yu

Blockchain technology has attracted more and more attention from academia and industry recently. Ethereum, which uses blockchain technology, is a distributed computing platform and operating system. Smart contracts are small programs deployed to the Ethereum blockchain for execution. Errors in smart contracts will lead to huge losses. Formal verification can provide a reliable guarantee for the security of blockchain smart contracts. In this paper, the formal method is applied to inspect the security issues of smart contracts. We summarize five kinds of security issues in smart contracts and present formal verification methods for these issues, thus establishing a formal verification framework that can effectively verify the security vulnerabilities of smart contracts. Furthermore, we present a complete formal verification of the Binance Coin (BNB) contract. It shows how to formally verify the above security issues based on the formal verification framework in a specific smart contract. All the proofs are checked formally using the Coq proof assistant in which contract model and specification are formalized. The formal work of this paper has a variety of essential applications, such as the verification of blockchain smart contracts, program verification, and the formal establishment of mathematical and computer theoretical foundations.

Yeṣem Kurt Peker, Xavier Rodríguez, James Ericsson, Suk Jin Lee · 5 authors

Blockchain is a developing technology that can be utilized for secure data storage and sharing. In this work, we examine the cost of Blockchain-based data storage for constrained Internet of Things (IoT) devices. We had two phases in the study. In the first phase, we stored data retrieved from a temperature/humidity sensor connected to an Ethereum testnet blockchain using smart contracts in two different ways: first, appending the new data to the existing data, storing all sensor data; and second, overwriting the new data onto the existing data, storing only a recent portion of the data. In the second phase, we stored simulated data from several sensors on the blockchain assuming sensor data is numeric. We proposed a method for encoding the data from the sensors in one variable and compared the costs of storing the data in an array versus storing the encoded data from all sensors in one variable. We also compared the costs of carrying out the encoding within the smart contract versus outside the smart contract. In the first phase, our results indicate that overwriting data points is more cost-efficient than appending them. In the second phase, using the proposed encoding method to store the data from several sensors costs significantly less than storing the data in an array, if the encoding is done outside the smart contract. If the encoding is carried out in the smart contract, the cost is still less than storing the data in an array, however, the difference is not significant. The study shows that even though expensive, for applications where the integrity and transparency of data are crucial, storing IoT sensor data on Ethereum could be a reliable solution.

G. A. Pierro, Roberto Tonelli

Smart Contracts are computer programs which implement and execute transactions and manage business logic on a decentralized public ledger. Smart Contracts can be written in different programming languages and for different Blockchains. Currently the most used language for Smart Contracts is Solidity and the most used platform is the Ethereum Blockchain. Assessing the quality of Smart Contract programs is an important task required to professional programmers, especially when a programming language has so powerful economic implications. It is therefore crucial to provide professional programmers with tools for the evaluation of Smart Contracts. In software engineering, software metrics has been defined and used to measure software quality and, more in general, to qualify software under the principle “You Can't Manage What You Don't Measure”. For the Solidity programming language there are only a few Standalone Applications to analyse the Smart Contract metrics. The aim of this paper is first to build a tool for the practical computation of a specific set of Solidity source code metrics, so that the set will be extensible in the future according also to Solidity compiler evolution, second to fully enable a web-based usage of the tool to access the metrics of the Solidity programming language. The tool, PASO, differently from the existing application, is able to give software metrics values for Smart Contracts written in Solidity programming language just using a web browser.

Yun Zhang, Zhi Tang, Jing Huang, Yue Ding · 7 authors

The copyright of data is a key point that needs to be solved in spatial data infrastructure for data sharing. In this paper, we propose a decentralized digital rights management model of spatial data, which can provide a novel way of solving the existing copyright management problem or other problems in spatial data infrastructure for data sharing. An Ethereum smart contract is used in this model to realize spatial data digital rights management function. The InterPlanetary File System is utilized as external data storage for storing spatial data in the decentralized file system to avoid data destruction that is caused by a single point of failure. There is no central server in the model architecture, which has a completely decentralized nature and it makes spatial data rights management not dependent on third-party trust institutions. We designed three spatial data copyright management algorithms, developed a prototype system to implement and test the model, used the smart contract security verification tool to check code vulnerabilities, and, finally, discussed the usability, scalability, efficiency, performance, and security of the proposed model. The result indicates that the proposed model not only has diversified functions of copyright management compared with previous studies on the blockchain-based digital rights management, but it can also solve the existing problems in traditional spatial data infrastructure for data sharing due to its characteristics of complete decentralization, mass orientation, immediacy, and high security.

Marco Savi, Daniele Santoro, Katarzyna Di Meo, Daniele Pizzolli · 9 authors

This demonstration aims at showcasing an initial version of the DECENTER Brokerage Platform, which leverages an Ethereum blockchain to enable resource federation among different Fog Computing infrastructures. We consider a scenario where an Italian Infrastructure Provider wants to seamlessly extend its pool of resources to get access to an IP camera located in Korea, so that it can deploy an application to locally perform text recognition from a live video stream.

Noama Fatima Samreen, Manar H. Alalfi

Ethereum Smart contracts use blockchain to transfer values among peers on networks without central agency. These programs are deployed on decentralized applications running on top of the blockchain consensus protocol to enable people to make agreements in a transparent and conflict-free environment. The security vulnerabilities within those smart contracts are a potential threat to the applications and have caused huge financial losses to their users. In this paper, we present a framework that combines static and dynamic analysis to detect Reentrancy vulnerabilities in Ethereum smart contracts. This framework generates an attacker contract based on the ABI specifications of smart contracts under test and analyzes the contract interaction to precisely report Reentrancy vulnerability. We conducted a preliminary evaluation of our proposed framework on 5 modified smart contracts from Etherscan and our framework was able to detect the Reentrancy vulnerability in all our modified contracts. Our framework analyzes smart contracts statically to identify potentially vulnerable functions and then uses dynamic analysis to precisely confirm Reentrancy vulnerability, thus achieving increased performance and reduced false positives.

Lodovica Marchesi, Michele Marchesi, Giuseppe Destefanis, Giulio Barabino · 5 authors

Blockchain technology is an emerging technology that allows new forms of decentralized architectures, designed to generate trust among users, without the intervention of mediators or knowledge between the parties. Since 2015, thanks to the introduction of Smart Contracts by Ethereum, it is possible to run programs on the blockchain, greatly extending the potential of this technology. The programming of Smart Contract, through the Solidity language is different from the traditional one. First of all, any action that requires to modify the blockchain costs gas, which corresponds to a fraction of the currency used by that given blockchain, and therefore to real money. Gas optimization is a unique challenge in this context and has obvious implications. This document aims to provide a set of design patterns and tips to help gas saving in developing Smart Contracts on Ethereum. The provided patterns are presented divided into five main categories, based on their features.

Amrita Jyoti, R. K. Chauhan

Before the invention of the various technologies, managing various activities and actions over the internet was achieved through a centralized server to guarantee valid data. With the expanding measure of accessible storage space and the quickening of data stream incited by the internet, a developing enthusiasm for data about the creation procedure and sources of information has developed. While this wide scope of use territories would profit by provenance data, the kind of provenance information, manipulation and querying facilities required vary from application to application. In this way, to discover the distinctions and similitudes between the different application and information model provenance needs and present a general plan for the arrangement of provenance. By characterizing this plan and applying it to existing work we plan to uncover open inquiries in the region of information provenance In this paper we survey the blockchain and provenance of the data in rice supplychain. We implement our proposed approach using smart contract which is to be deploy on ethereum blockchain network in rice supplychain to show the security and provenance of the data . We can track the progress of rice batch after each stage in blockchain and also discussed the need of provenance of assets in supplychain as it increase the trust of the customer

Md. Selim Hossain, Sajjad Waheed, Ziaur Rahman, Sk. A. Shezan · 5 authors

Internet of Things (IoT) that has been developed owing toward the merging of various technologies such as instantaneous analytics, machine learning, artificial neural network, product sensors and implanted systems, etc. It also stages a significant part in multiple applications which are a smart city, smart home, agricultural, health monitoring, tourism, transportation, communication, business, education, etc. The security concern associating IoT has to be situated in the direction to attract the research community due to its immensely growing application in our daily life. Since it is light-weight nature, the security mechanism needs changes apart from comprehensive web security. PKI based certificate driven techniques, which in some instances seem not appropriate on the way toward encounter IoT challenges, e.g., as real-time effectiveness, costs, and performance from the security perspective. However, Blockchain has mind-blowing potentials to peer with the IoT aiming to build trust, transparency, and security. Its distinct properties, such as distributed behavior, immutability, and consensus mechanism, can stimulate and improve the rapidly growing IoT system through meaningful integration. We propose to address a practical smart home use case scenario using Ethereum Blockchain to improve IoT security. Public type and smart contract oriented Ethereum Blockchain are adaptable to enhance IoT security remains individual of the contributions that we claim throughout this research work.

Andrew Burnie, Emine Yılmaz, Tomaso Aste

The recent extreme volatility in cryptocurrency prices occurred in the setting of popular social media forums devoted to the discussion of cryptocurrencies. We develop a framework that discovers potential causes of phasic shifts in the price movement captured by social media discussions. This draws on principles developed in healthcare epidemiology where, similarly, only observational data are available. Such causes may have a major, one-off effect or recurring effects on the trend in the price series. We find a one-off effect of regulatory bans on bitcoin, the repeated effects of rival innovations on ether and the influence of technical traders, captured through discussion of market price, on both cryptocurrencies. The results for Bitcoin differ from Ethereum, which is consistent with the observed differences in the timing of the highest price and the price phases. This framework could be applied to a wide range of cryptocurrency price series where there exists a relevant social media text source. Identified causes with a recurring effect may have value in predictive modelling, whilst one-off causes may provide insight into unpredictable black swan events that can have a major impact on a system.

Christopher Klinkmüller, Ingo Weber, Alexander Ponomarev, An Binh Tran · 5 authors

Second generation blockchain platforms, like Ethereum, can store arbitrary data and execute user-defined smart contracts. Due to the shared nature of blockchains, understanding the usage of blockchain-based applications and the underlying network is crucial. Although log analysis is a well-established means, data extraction from blockchain platforms can be highly inconvenient and slow, not least due to the absence of logging libraries. To close the gap, we here introduce the Ethereum Logging Framework (ELF) which is highly configurable and available as open source. ELF supports users (i) in generating cost-efficient logging code readily embeddable into smart contracts and (ii) in extracting log analysis data into common formats regardless of whether the code generation has been used during development. We provide an overview of and rationale for the framework's features, outline implementation details, and demonstrate ELF's versatility based on three case studies from the public Ethereum blockchain.

Wei Wang, J. J. Song, Guangquan Xu, Yidong Li · 6 authors

Smart contracts are decentralized applications running on Blockchain. A very large number of smart contracts has been deployed on Ethereum. Meanwhile, security flaws of contracts have led to huge pecuniary losses and destroyed the ecological stability of contract layer on Blockchain. It is thus an emerging yet crucial issue to effectively and efficiently detect vulnerabilities in contracts. Existing detection methods like Oyente and Securify are mainly based on symbolic execution or analysis. These methods are very time-consuming, as the symbolic execution requires the exploration of all executable paths or the analysis of dependency graphs in a contract. In this work, we propose ContractWard to detect vulnerabilities in smart contracts with machine learning techniques. First, we extract bigram features from simplified operation codes of smart contracts. Second, we employ five machine learning algorithms and two sampling algorithms to build the models. ContractWard is evaluated with 49502 real-world smart contracts running on Ethereum. The experimental results demonstrate the effectiveness and efficiency of ContractWard. The predictive Micro-F1 and Macro-F1 of ContractWard are over 96% and the average detection time is 4 seconds on each smart contract when we use XGBoost for training the models and SMOTETomek for balancing the training sets.

Lin Chen, Lei Xu, Zhimin Gao, Sunny, Ahmed · 6 authors

Recent advances in the blockchain research have been made in two important directions. One is refined resilience analysis utilizing game theory to study the consequences of selfish behaviors of users (miners), and the other is the extension from a linear (chain) structure to a non-linear (graphical) structure for performance improvements, such as IOTA and Graphcoin. The first question that comes to people's minds is what improvements that a blockchain system would see by leveraging these new advances. In this paper, we consider three major metrics for a blockchain system: full verification, scalability, and finality-duration. We { establish a formal framework and} prove that no blockchain system can achieve full verification, high scalability, and low finality-duration simultaneously. We observe that classical blockchain systems like Bitcoin achieves full verification and low finality-duration, Harmony and Ethereum 2.0 achieve low finality-duration and high scalability. As a complementary, we design a non-linear blockchain system that achieves full verification and scalability. We also establish, for the first time, the trade-off between scalability and finality-duration.

Dan Lin, Jiajing Wu, Qi Yuan, Zibin Zheng

As the largest public blockchain-based platform supporting smart contracts, Ethereum has accumulated a large number of user transaction records since its debut in 2014. Analysis of Ethereum transaction records, however, is still relatively unexplored till now. Modeling the transaction records as a static simple graph, existing methods are unable to accurately characterize the temporal and multiplex features of the edges. In this brief, we first model the Ethereum transaction records as a complex network by incorporating time and amount features of the transactions, and then design several flexible temporal walk strategies for random-walk based graph representation of this large-scale network. Experiments of temporal link prediction on real Ethereum data demonstrate that temporal information and multiplicity characteristic of edges are indispensable for accurate modeling and understanding of Ethereum transaction networks.