In recent years, blockchain technology has created a new cryptocurrency world and has attracted a lot of attention. It also is rampant with various scams. For example, phishing scams have grabbed a lot of money and has become an important threat to users' financial security in the blockchain ecosystem. To help deal with this issue, this paper proposes a systematic approach to detect phishing accounts based on blockchain transactions and take Ethereum as an example to verify its effectiveness. Specifically, we propose a graph-based cascade feature extraction method based on transaction records and a lightGBM-based Dual-sampling Ensemble algorithm to build the identification model. Extensive experiments show that the proposed algorithm can effectively identify phishing scams.
Currently, technologies are developing very quickly and the need for information security is constantly increasing. In this connection, Blockchain technology is becoming in demand, which allows us to keep information safety and integrity. In addition, the technology enables the creation of a decentralized environment where transactions and data are take place without any third party organization. We proposed a decentralized web resource based on the Ethereum platform for managing student credits. The decentralized application (Dapp), will process, manage and control tokens, which represent credits that students gain for completed certain courses. The credit system is a first step towards a more transparent and technologically advanced form which could be used by universities and students to manage credits. The novelty of this scientific research is the creation of a web-based information resource based on Blockchain technology. Thanks to this resource, it becomes possible to track students' grades and receive reliable information about higher education. This completely eliminates the possibility of making changes to existing records.
The current pandemic situation has made us realize how fake news can have detrimental impacts on society. Although we can't ignore the benefits of social media, we surely can't overlook the misuse of these mediums to spread rumors and fake articles. These posts/ articles/ messages can be commonly called "Fake News" and they not only create misinformation but also create panic among the public. Blockchain is a disruptive technology that is being used to make innovative solutions in the sectors of food, fashion, supply chain, and banking. The decentralized and transparent nature of blockchain can not only be used in the above sectors but it can also be used to tackle the problem of fake news. Several solutions have been proposed to combat the problem using blockchain. This paper will propose one such solution to combat the fake news problem that can be used by all the news agencies. The system is called the "News Tracking and Tracing System " and is built using Ethereum.
The growing use of smart contracts in a wide range of transactions has raised a deluge of legal issues, including allocation of liability in such transactions. In many circumstances, using smart contracts involves a range of legal risks that might be distributed beyond the contractual parties to other parties, such as the developers of the smart contract code. While smart contracts have the potential to disrupt the current legal and transactional status quo, notorious occurrences such as attacks on Ethereum or Bitcoin platforms highlight the need to properly dissect the issue of liability and rightly apportion liability where it falls. This also includes working on any lapses in the existing legal and transactional framework to cater for these issues. This article sets out to examine the validity of smart contracts in the light of existing contract law principles. It examined the legal regime and development of smart contracts in Nigeria. It further discussed the problem of allocation of liability associated with smart contracts. It made certain propositions on how these issues could be tackled including the amendment of existing legal framework to aptly provide for and regulate the smart contracts era particularly in Nigeria. The doctrinal method of research was employed to dissect the issues raised and discussed in the article. Relevant texts were scrutinized and analyzed to arrive at the findings and recommendations contained in the article.
Abstract Blockchain-based cloud application (BCP) is an emerging cloud application architecture. By moving trust-critical functions onto blockchain, BCP offers unprecedented function transparency and data integrity. Ethereum is by far the most popular blockchain platform chosen for BCP. In Ethereum, special programs named smart contracts are often used to implement key components for BCP. By design, users can send transactions to smart contracts, which will automatically lead to code execution and state modification. However, unlike regular programs, smart contracts are restricted in execution by gas limit, i.e., a form of runtime resource. If a transaction uses up all available gas, an out of gas exception () will trigger, reverting state until right before that transaction.In this work, we study the out of gas exceptions (or gas exceptions in short) on Ethereum empirically for the very first time. In particular, we collect exception transactions using an instrumented Ethereum client. By investigation, we found gas exceptions stand out in terms of both occurrences and losses. Moreover, we focused on individual contracts and transactions, aiming at discovering and identifying common causing factors triggering these exceptions. At last, we also investigate existing tools in preventing gas exceptions. Our results suggest further research and study in this direction.
Ijazah konvensional mempunyai beberapa kekurangan diantaranya yaitu bisa dipalsukan, membutuhkan tempat pemyimpanan yang aman dan bisa rusak. Oleh karena perlu dibuat teknologi informasi yang bisa mengatasi kekurangan tersebut, salah satunya adalah smart contract pada blockchain Ethereum. Smart contract pada blockchain Ethereum memungkinkan membuat ijazah dengan integritas dan keamanan data yang tinggi, sehingga bisa meminimalisir kerusakan dan pemalsuan ijazah. Akan tetapi blockchain Ethereum memerlukan biaya yang besar dalam menyimpan data yang besar. Pada penelitian ini bertujuan guna mengukur performa dari pengimplementasian IPFS pada smart contract yang dapat membuat biaya transaksi lebih stabil dan murah sebesar 61,95% dibandingkan dengan blockchain Ethereum tanpa mengimplementasikan IPFS. Selain itu, performa pada smart contract yang mengimplementasikan IPFS dapat meningkatkan performa dari Quality of Service (QoS) dengan parameter throughput sebesar 6,04 kali, Packet Loss 39,47%, dan Latency 42,28%.
As the blockchain 2.0 platform, Ethereum's turing complete programming language and smart contract components make it play an important role in the commercialization of blockchain. With the further development of blockchain applications, the privacy and security issues of Ethereum have gradually emerged. To solve this problem, we proposed a blockchain privacy protection model called RZcash in the previous work. It implements the dynamically updateable and verifiable hiding of the asset information in Ethereum, namely the account balance and transaction amount. However, RZcash does not pay attention to the key redundancy problem that may be caused by the creation of secret accounts. In addition, the large size of proofs gives it high communication costs. In response to these problems, we further improve RZcash. For the key redundancy problem, we construct a new signature scheme based on the ciphertext equivalent test commitment. Moreover, we use the Schnorr signature and bulletproof to improve the corresponding proof scheme in RZcash, thereby reducing the size of proof. Based on these improvements, we propose a decentralized payment system, called RZcoin, based on Ethereum. Finally, we implement the algorithm model of RZcoin and evaluate its security and performance. The results show that RZcoin has higher security and Lower communication cost than RZcash.
Crowdsourcing is a process wherein an individual or an organisation utilizes\nthe talent pool present over the Internet to accomplish their task. The\nexisting crowdsourcing platforms and their reputation computation are\ncentralised and hence prone to various attacks or malicious manipulation of the\ndata by the central entity. A few distributed crowdsourcing platforms have been\nproposed but they lack a robust reputation mechanism. So we propose a\ndecentralised crowdsourcing platform having an immutable reputation mechanism\nto tackle these problems. It is built on top of Ethereum network and does not\nrequire the user to trust a third party for a non malicious experience. It also\nutilizes IOTAs consensus mechanism which reduces the cost for task evaluation\nsignificantly.\n
Blockchain is a secure and distributed ledger structure and each block is a cryptographic hash of some other factors like a timestamp. The chain is formed by linking the blocks and distributed data is present on multiple computers. The blockchain made system are more fault-tolerant and has high availability even in times of database failures. Though Linux is considered a benchmark for security, it is susceptible to various attacks. With the use of blockchain, Linux logs can be made more transparent among multiple root users and secured by hosting the logs on a decentralized Ethereum blockchain which is customized as per the requirement. It has been observed that in a scenario with multiple root users working simultaneously on same system, transparency between multiple root users can be compromised if some appropriate changes are made in few lines containing the history, Hence, with the help of Ethereum blockchain and log monitoring using log monitors, it is much easier to track the intrusions to identify the source of unauthorized access to logs or changes in them.
Gracie Carter, Ben Chevellereau, Hossain Shahriar, Sweta Sneha
The healthcare system in the United States is unique. From payor to provider, patients have the freedom of choice. This creates a complicated and profitable paradigm of care. Legislation defines government expectations of data exchange; however, the methods are left to the discretion of the stakeholders. Today, devices and programs are not built to unified standards, thus they do not share data easily. This communication between software is known as interoperability. We address the health data interoperability by leveraging Fast Health Interoperable Resource (FHIR) standard, a viewer of FHIR called OpenPharma, and Blockchain technology. Our proof of concept, called "OpenPharma Blockchain on FHIR" (OBF), is interoperable by design and grants clinicians access to patient records using a combination of data standards, distributed applications, patient-driven identity management, and the Ethereum blockchain. OBF is a trustless, secure, decentralized, and vendor-independent method for information exchange. It is easy to implement and places the control of records with the patients.
Itay Tsabary, Matan Yechieli, Alex Manuskin, Ittay Eyal
Smart Contracts and transactions allow users to implement elaborate constructions on cryptocurrency blockchains like Bitcoin and Ethereum. Many of these constructions, including operational payment channels and atomic swaps, use a building block called Hashed Time-Locked Contract (HTLC). In this work, we distill from HTLC a specification (HTLC-Spec), and present an implementation called Mutual-Assured-Destruction Hashed Time-Locked Contract (MAD-HTLC). MAD-HTLC employs a novel approach of utilizing the existing blockchain operators, called miners, as part of the design. If a user misbehaves, MAD-HTLC incentivizes the miners to confiscate all her funds. We prove MAD-HTLC's security using the UC framework and game-theoretic analysis. We demonstrate MAD-HTLC's efficacy and analyze its overhead by instantiating it on Bitcoin's and Ethereum's operational blockchains. Notably, current miner software makes only little effort to optimize revenue, since the advantage is relatively small. However, as the demand grows and other revenue components shrink, miners are more motivated to fully optimize their fund intake. By patching the standard Bitcoin client, we demonstrate such optimization is easy to implement, making the miners natural enforcers of MAD-HTLC. Finally, we extend previous results regarding HTLC vulnerability to bribery attacks. An attacker can incentivize miners to prefer her transactions by offering high transaction fees. We demonstrate this attack can be easily implemented by patching the Bitcoin client, and use game-theoretic tools to qualitatively tighten the known cost bound of such bribery attacks in presence of rational miners. We identify bribe opportunities occurring on the Bitcoin and Ethereum main networks where a few dollars bribe could yield tens of thousands of dollars in reward (e.g., \$2 for over \$25K).
There is a lot of excitement around Blockchain technology and its ability to disrupt many traditional industries and business practices. First invented as a part of Bitcoin’s underlying infrastructure, Blockchain technology offers a platform for decentralized and transparent transaction management between untrusting parties. Many believe this aspect of blockchain can revolutionize traditional supply chain practices typically involving many untrusting entities from the time raw material extraction to the final consumption of a finished product by the end consumer. While there have been many claims regarding its obvious benefits in Supply chain management, there are only few technical applications developed so far that are useful in real world scenarios. In this thesis, we review different real-world implementations of block chain technology in the supply chain domain, especially those that leverage smart contracts. Smart contract is a computer protocol that facilitates, verifies, enforces performance of a contract digitally using Blockchain technology. Since smart contracts are trackable, irreversible and allow performance of credible transactions without third parties, it can be deployed effectively to replace existing supply chain mechanisms that require working with an intermediate entity such as a bank that often comes with a price tag for their services. In this thesis, we present a framework to enable sale of goods between untrusting entities typically in different geographies leveraging smart contract technology that can effectively replace the "letter of credit" payment mechanism. An novel algorithm for dispute resolution is developed and a decentralized app (Dapp) is built and deployed on Ethereum block chain using smart contracts developed in Solidity. Last, we discuss the effectiveness of such a system, potential drawbacks or known security threats that may hinder the adoption of such an app in the real world.
The protocol for cryptocurrencies can be divided into three parts, namely consensus, wallet, and networking overlay. The aim of the consensus part is to bring trustless rational peer-to-peer nodes to an agreement to the current status of the blockchain. The status must be updated through valid transactions. A proof-of-work (PoW) based consensus mechanism has been proven to be secure and robust owing to its simple rule and has served as a firm foundation for cryptocurrencies such as Bitcoin and Ethereum. Specialized mining devices have emerged, as rational miners aim to maximize profit, and caused two problems: i) the re-centralization of a mining market and ii) the huge energy spending in mining. In this paper, we aim to propose a new PoW called Error-Correction Codes PoW (ECCPoW) where the error-correction codes and their decoder can be utilized for PoW. In ECCPoW, puzzles can be intentionally generated to vary from block to block, leading to a time-variant puzzle generation mechanism. This mechanism is useful in repressing the emergence of the specialized mining devices. It can serve as a solution to the two problems of recentralization and energy spending.
Mayra Samaniego, Sara Hosseinzadeh Kassani, Cristian Espana, Ralph Deters
Computer-Aided Diagnosis (CAD) systems have emerged to support clinicians in interpreting medical images. CAD systems are traditionally combined with artificial intelligence (AI), computer vision, and data augmentation to evaluate suspicious structures in medical images. This evaluation generates vast amounts of data. Traditional CAD systems belong to a single institution and handle data access management centrally. However, the advent of CAD systems for research among multiple institutions demands distributed access management. This research proposes a blockchain-based solution to enable distributed data access management in CAD systems. This solution has been developed as a distributed application (DApp) using Ethereum in a consortium network.
Web-based public participatory GIS (PPGIS) has been used by governmental organizations to facilitate people's contribution to decision-making processes. However, these applications do not provide an open and transparent environment for public participation. This study suggests that PPGISs should be developed as decentralized applications (DApp) based on Ethereum blockchain technology to have a fully open, transparent, and accountable environment for public participation. In a blockchain-based PPGIS, the collected data are securely saved on the blockchain. The validity of the data, replicated on the nodes of the peer-to-peer blockchain network, is ensured through a consensus process without any central control. The data is tamper-free and immutable. Additionally, the data is openly accessible to institutions and citizens. A prototype PPGIS was developed as a DApp through which users can participate in the site selection of urban facilities. Using the application, they compare and rank different criteria. The system solves an analytic hierarchy process to calculate the weights of the criteria. A suitability map is generated afterward and published to be used by both citizens and decision-makers. The feasibility of the application, along with the issues that need to be considered while using blockchain technology for urban planning and development, are thoroughly discussed.
The analysis of cryptocurrencies market behaviour is receiving significant attention from researchers and practitioners in the last decades. This paper aims at contributes to volatility estimations of the cryptocurrencies helping to highlight the main stylized facts and characteristics. The performance of different specifications of volatility modelling, within the GARCH class, have been compared through the Model Confidence Set (MCS) over four of the most capitalised cryptocurrencies, namely Bitcoin, Ethereum, Stellar and Ripple. Our empirical findings give evidence of strong asymmetric effects in cryptocurrencies volatility leading to a better performance of asymmetric GARCH specifications..
Marten Sigwart, Michael Borkowski, Marco Peise, Stefan Schulte · 5 authors
Abstract As data collected and provided by Internet of Things (IoT) devices power an ever-growing number of applications and services, it is crucial that this data can be trusted. Data provenance solutions combined with blockchain technology are one way to make data more trustworthy by providing tamper-proof information about the origin and history of data records. However, current blockchain-based solutions for data provenance fail to take the heterogeneous nature of IoT applications and their data into account. In this work, we identify functional and non-functional requirements for a secure and extensible IoT data provenance framework, and conceptualise the framework as a layered architecture. Evaluating the framework using a proof-of-concept implementation based on Ethereum smart contracts, we conclude that our framework can be used to realise data provenance concepts for a wide range of IoT use cases. While blockchain technology generally poses constraints on scalability and privacy, we discuss multiple solutions aiming to overcome these issues.
Direct bartering allows for the trading of assets with or without the use of money. In this paper, we introduce a smart contract written in the Solidity language for the Ethereum blockchain that implements a distributed and autonomous direct barter exchange operated by crowds. Since ERC20 smart contract tokens are widely used for initial coin offerings (ICOs), our implementation provides autonomous bartering services for ERC20 tokens. The non-fungible ERC721 token, as well as Ethereum Name Service (ENS) name bartering, are also supported. Because finding a feasible bartering solution for bids involving multiple tokens is NP-hard in general, our exchange only provides escrow and swapping services. It assumes feasible solutions are submitted by bartering problem solvers from the crowd who run a solver locally on their machines. Bartering problem solvers are incentivized to submit solutions to the autonomous exchange by awarding them with excess tokens that are left over after granting the bidders the tokens they requested in their bids. Our system, called BarterMachine, can perhaps be used to facilitate a global barter economy. The BarterMachine prototype is available for testing on the Ethereum Ropsten network at https://bartermachine.github.io/bartermachine/ropsten/.
Huashan Chen, Marcus Pendleton, Laurent Njilla, Shouhuai Xu
Blockchain technology is believed by many to be a game changer in many application domains. While the first generation of blockchain technology (i.e., Blockchain 1.0) is almost exclusively used for cryptocurrency, the second generation (i.e., Blockchain 2.0), as represented by Ethereum, is an open and decentralized platform enabling a new paradigm of computing—Decentralized Applications (DApps) running on top of blockchains. The rich applications and semantics of DApps inevitably introduce many security vulnerabilities, which have no counterparts in pure cryptocurrency systems like Bitcoin. Since Ethereum is a new, yet complex, system, it is imperative to have a systematic and comprehensive understanding on its security from a holistic perspective, which was previously unavailable in the literature. To the best of our knowledge, the present survey, which can also be used as a tutorial, fills this void. We systematize three aspects of Ethereum systems security: vulnerabilities, attacks, and defenses. We draw insights into vulnerability root causes, attack consequences, and defense capabilities, which shed light on future research directions.
Cryptocurrency has seen an explosive growth in recent years, thanks to the evolvement of blockchain technology and its economic ecosystem. Besides Bitcoin, thousands of cryptocurrencies have been distributed on blockchains, while hundreds of cryptocurrency exchanges are emerging to facilitate the trading of digital assets. At the same time, it also attracts the attentions of attackers. Fake deposit, as one of the most representative attacks (vulnerabilities) related to exchanges and tokens, has been frequently observed in the blockchain ecosystem, causing large financial losses. However, besides a few security reports, our community lacks of the understanding of this vulnerability, for example its scale and the impacts. In this paper, we take the first step to demystify the fake deposit vulnerability. Based on the essential patterns we have summarized, we implement DEPOSafe, an automated tool to detect and verify (exploit) the fake deposit vulnerability in ERC-20 smart contracts. DEPOSafe incorporates several key techniques including symbolic execution based static analysis and behavior modeling based dynamic verification. By applying DEPOSafe to 176,000 ERC-20 smart contracts, we have identified over 7,000 vulnerable contracts that may suffer from two types of attacks. Our findings demonstrate the urgency to identify and prevent the fake deposit vulnerability.
Blockchain technology provides an auditable and tamper-proof distributed storage infrastructure for information records. This can be leveraged to support distributed workflow management. Compared to proof-of-work consensus, popularized by Bitcoin and Ethereum, blockchains based on BFT (byzantine fault tolerance) ordering consensus trade scalability for immediacy and finality of consensus. This makes them easier to use as distribution infrastructure, as applications need not be adapted to deal with eventual consistency and delayed consensus of proof-of-work blockchains. Hence, applications such as workflow engines can be easily ported to such a blockchain infrastructure to take advantage of their decentralized integrity assurance and information distribution model. In this paper we describe how the YAWL workflow engine can be used on a BFT based blockchain infrastructure to enable collaborative workflows across different organizations.
As criptomoedas surgem como uma maneira diferenciada de se efetuar pagamentos, principalmente no âmbito online. As criptomoedas se tratam de um modelo de moeda virtual cujas principais características são a descentralização e o anonimato de seus usuários. O presente trabalho buscou relacionar as criptomoedas com o setor do turismo, tomando por base um levantamento bibliográfico para compreender o que são as criptomoedas e o seu funcionamento, seguido de uma análise de 255 notícias em portais de notícias especializados em negócios que tratavam de criptomoedas e suas aplicações no mercado. Com isso constatou-se que as cinco criptomoedas mais utilizadas para venda de serviços turísticos são o Bitcoin, Litecoin, Bitcoin Cash, Ethereum e DASH. Algumas características dessas criptomoedas como o seu preço e taxa para realização de transação foram abordadas na pesquisa para melhor entender como elas poderiam ser implementadas no setor turístico. Conclui-se que as criptomoedas são uma forma diferente de se efetuar transações que pode trazer comodidade e ao mesmo tempo riscos para os turistas. Agradecimentos ao CNPq pela concessão de bolsa para realização da pesquisa.
Yulia M. Beketnova, Grigory O. Krylov, Leonid I. Polyakov, Andrey S. Denisenko · 5 authors
The object of the research is the leading national fiat currencies and transnational anonymous analogues of the currency. They have received the slang name of cryptocurrencies. The subject of the study is volatility. It is the most important financial indicator in the management of financial flows, as a measure of risk of using a financial instrument at a specified time interval. The subject of the research requires consideration of digital goods of limited emission, which are the product of energy conversion into information in the form of a program code on a tangible medium. The limited amount of the emission for these goods without the syndrome of “printing press” has served as a basis for the name “cryptocurrency” and “digital gold”. The issue of cryptocurrency is a reward in the competitive procedure of checking transactions in peer-to-peer networks that implement the technology of distributed registries, and it is essentially a by-product of their functioning. The significant feature of such a product is anonymity and cross-border. They give rise to fundamental legal issues. Cryptocurrency obtaining technology is available to general public and has become an innovative phenomenon. The latest financial phenomena need to be investigated, so it is necessary to conduct a multilateral scientific analysis, identification and comparison of cryptocurrency with the fiat currency. The article compares the volatility of different currencies such as fiat (US dollar, euro, Chinese yuan and Japanese yen) and the most popular cryptocurrencies (Bicoin, Litecoin, Ethereum and Monero) at the present time. The aim of the study is to obtain new estimates of cryptocurrency based on the use of tools such as GARCH model, simple historical volatility (SHV) and developed by the authoring tool, which is based on the Chaikin method.