Smart contracts — computer protocols that regulate the exchange of crypto-assets in trustless environments — have become popular with the spread of blockchain technologies. A landmark security property of smart contracts is liquidity: in a non-liquid contract, it may happen that some assets remain frozen, i.e. not redeemable by anyone. The relevance of this issue is witnessed by recent liquidity attacks to Ethereum, which have frozen hundreds of USD millions. We address the problem of verifying liquidity on BitML, a DSL for smart contracts with a secure compiler to Bitcoin, featuring primitives for currency transfers, contract renegotiation and consensual recursion. Our main result is a verification technique for liquidity. We first transform the infinite-state semantics of BitML into a finite-state one, which focusses on the behaviour of a chosen set of contracts, abstracting from the moves of the context. With respect to the chosen contracts, this abstraction is sound, i.e. if the abstracted contract is liquid, then also the concrete one is such. We then verify liquidity by model-checking the finite-state abstraction. We implement a toolchain that automatically verifies liquidity of BitML contracts and compiles them to Bitcoin, and we assess it through a benchmark of representative contracts.
Smart contracts - computer protocols that regulate the exchange of crypto-assets in trustless environments - have become popular with the spread of blockchain technologies. A landmark security property of smart contracts is liquidity: in a non-liquid contract, it may happen that some assets remain frozen, i.e. not redeemable by anyone. The relevance of this issue is witnessed by recent liquidity attacks to Ethereum, which have frozen hundreds of USD millions. We address the problem of verifying liquidity on BitML, a DSL for smart contracts with a secure compiler to Bitcoin, featuring primitives for currency transfers, contract renegotiation and consensual recursion. Our main result is a verification technique for liquidity. We first transform the infinite-state semantics of BitML into a finite-state one, which focusses on the behaviour of a chosen set of contracts, abstracting from the moves of the context. With respect to the chosen contracts, this abstraction is sound, i.e. if the abstracted contract is liquid, then also the concrete one is such. We then verify liquidity by model-checking the finite-state abstraction. We implement a toolchain that automatically verifies liquidity of BitML contracts and compiles them to Bitcoin, and we assess it through a benchmark of representative contracts.
In this study we discuss the determinants of the BRICS and GCC stock market returns during the COVID-19 outbreak. We employ the OLS regression to discern how crypto-currencies, VIX, oil, GOLD prices, and the number of COVID-19 cases and deaths, affect the Gulf and BRICS stock markets. We find that Bitcoin and Ethereum can generate benefits from portfolio diversification and hedging strategies but not from safe haven strategies for Russia, Brazil, Abu-Dhabi, Bahrain, and Qatar financial investors during the COVID-19 outbreak. Our results reveal that Gold is neither hedge nor a safe haven but is only an effective diversifier for investors during the COVID-19 outbreak. The results indicated that among all the BRICS and GCC stock indexes, the expected volatility of the US stock market has an effect only on china and Kuwait financial markets. Finally, our results show that the growth rate of confirmed COVID-19 cases has a negative impact only on South Africa and Brazil stock market.
Decentralized blockchain platforms have enabled the secure exchange of crypto-assets without the intermediation of trusted authorities. To this purpose, these platforms rely on a peer-to-peer network of byzantine nodes, which collaboratively maintain an append-only ledger of transactions, called blockchain. Transactions represent the actions required by users, e.g. the transfer of some units of crypto-currency to another user, or the execution of a smart contract which distributes crypto-assets according to its internal logic. Part of the nodes of the peer-to-peer network compete to append transactions to the blockchain. To do so, they group the transactions sent by users into blocks, and update their view of the blockchain state by executing these transactions in the chosen order. Once a block of transactions is appended to the blockchain, the other nodes validate it, re-executing the transactions in the same order. The serial execution of transactions does not take advantage of the multi-core architecture of modern processors, so contributing to limit the throughput. In this paper we develop a theory of transaction parallelism for blockchains, which is based on static analysis of transactions and smart contracts. We illustrate how blockchain nodes can use our theory to parallelize the execution of transactions. Initial experiments on Ethereum show that our technique can improve the performance of nodes.
Florian Adamsky, Daniel Kaiser, Michael Steglich, Thomas Engel
Distributed Hash Table (DHT) protocols, such as Kademlia, provide a decentralized key-value lookup which is nowadays integrated into a wide variety of applications, such as Ethereum, InterPlanetary File System (IPFS), and BitTorrent. However, many security issues in DHT protocols have not been solved yet. DHT networks are typically evaluated using mathematical models or simulations, often abstracting away from artefacts that can be relevant for security and/or performance. Experiments capturing these artefacts are typically run with too few nodes.
The exponential growth in energy demand led to increased demand-response gaps and decreased service quality of modern ICT-based smart grid (SG) in industry 4.0. It necessitates an efficient Demand Response Management (DRM) system in order to tackle aforementioned challenges. However, several DRM solutions exist, but these solutions are not adequate in terms of peak loads reduction, consumer comfort, and data security issues. Motivated from above facts, in this paper, we propose a scheme ϵ-Sutra, which is a security-aware DRM scheme for the SG system based on blockchain technology and integrated with data analytics. Here, a DRM algorithm is proposed to reduce peak energy consumption along with an incentive mechanism to consumers. ϵ-Sutra is incorporated with Ethereum-based smart contract (ESC) to handle security issues and InterPlanetary File System (IPFS) for data storage cost issues. The efficacy of the ϵ-Sutra scheme is evaluated in contrast with existing solutions based on various evaluation metrics.
Aasim Ullah, S.M. Shahnewaz Siddiquee, Md Akbar Hossain, Sayan Kumar Ray
Data security of present-day power systems, such as the electricity market, has spurred global interest in both industry and academia. The electricity market can either be regulated (state-controlled entrance, policies, and pricing) or deregulated (open for competitors). While the security threats in a deregulated electricity market are commonly known and have been investigated for years, those in a regulated market still have scope for extensive research. Our current work focuses on exploring the data security of the regulated electricity market, and the regulated New Zealand Electricity Market (NZEM) has been considered for this research. Although the chances of cyberattacks on state-controlled regulated electricity market are relatively less, different layers of the current SCADA systems do pose some threats. In this context, we propose a decentralized Ethereum Blockchain-based end-to-end security prototype for a regulated electricity market such as the NZEM. This prototype aims to enhance data security between the different layers of the current SCADA systems. The detailed operation process and features of this prototype are presented in this work. The proposed prototype has prospects of offering improved data security solutions for the regulated electricity market.
It was the 2008 Whitepaper penned by Satoshi Nakamoto and subsequently the January 3, 2009, that the world was introduced to the concept of decentralized cryptocurrencies through the Bitcoin’s system. This cryptocurrency quickly gained a huge amount of popularity. As a result, many other cryptocurrencies were born following its success. The years that followed the rise of Bitcoin saw a huge involvement of research communities spanning individuals, academia as well as industry, experimenting and formulating sound theoretical foundations behind the concept. Later, Ethereum (Buterin, 2014) was introduced to the world in the year 2015. Ethereum went on to become the second most popular blockchain-based system because it practically exemplified that blockchain as a concept can be decoupled from the notion of cryptocurrencies through its capability of processing smart contracts. After Bitcoin’s birth, it didn’t take long for the research community to recognize that cryptocurrency, even though it sounds very attractive, is not the main aspect of this system. The main aspect of this system was the Blockchain—a decentralized, distributed ledger that is maintained among a peer-to-peer network of computers through consensus. Research in the field of blockchain is sprawled out over a variety of subdomains-consensus, cryptography, proof-of-work, privacy, network—to name a few. In this chapter, the primary aim is to aggregate the existing attacks on blockchain-based systems. Consensus mechanism forms the spinal cord of any successful blockchain-based system. All other aspects of these systems 202 have their roots somewhere in the consensus mechanism followed in that system. In earlier sections, this provides an intuitive foundation on the most pervasive consensus mechanism currently employed by the leading distributed-ledger-technologies in this world—the proof of work. In the later sections of the chapter, a historical account of the variety of attacks that have been performed against blockchain-based systems is covered. In the last section, the chapter highlights some of the proposed models of attacks that have not been demonstrated at large yet but, are in currently seen as a possibility and therefore, are under research. This chapter will be aimed at affording the reader with an exposition catalog of the existing attacks on the blockchain-based systems, from a perspective of awareness.
With technology brazenly breaching through society’s barriers in countless diverse fields, the 21st century has revolutionized many age-old industries. One of the largest areas within society influenced by the progress of technology are the fields of finances, economy, and investment, coupled with the aspect of social influence. With this shift in society parallel to the advancement of contemporary technologies, thus becoming increasingly reliant on the tools made available, the complex yet traditional world of finance has pivoted, becoming contingent upon the use of cutting-edge technologies. This critical shift has introduced the world of Fintech, providing many innovative fiscal opportunities. The coined term, Fintech, is a general term referring to products as services for fiscal activities developed by entities unrelated to banks, insurance firms, nor online companies, providing alternatives to the traditional options available to the general public. (Gulamhuseinwala, Bull and Lewis, 2015). Resultantly of this Fintech trend, one of the largest and most promising fields of contemporary investment is recognized as that of Cryptocurrencies, with Bitcoin and Ethereum being the most recognized and heavily traded currencies. Many positive traits can be used to define the novelty of this new economy, with one of the main aspects being its peer to peer (P2P) nature of its trading process. However, beyond the tremendous advancements visible within the process of Cryptocurrency production and trade, one of the most important aspects is the influencers upon the valuation of the different currencies. Similarly to the progression of the economy which has transported the financial world to a digital economy, so has the social world, advancing discourse regarding many topics to the online environment. Thus, it is critical to analyze and assess the nature of online discourse regarding Cryptocurrencies. Explicitly, the chatter preceding to sharp rises and falls with Bitcoin and Ethereum, the most recognizable coins. Additionally, it is imperative to appraise the trends in the behavior and quantity of online discourse prior to a significant drop in Ethereum & Bitcoin.Within the online arena, there are countless different outlets and platforms for people to express themselves in general, or more importantly in this instance regarding the topic of Cryptocurrencies. By using platforms that are designated for discussion regarding financial topics or general social media platforms, the public is provided a critical platform utilized by countless individuals, many of whom are increasingly involved with the aforementioned topics. These platforms stipulate a stage for these individuals, who have become critical by voicing their opinions, thoughts, and experiences. Many of these influencers are sought after for their knowledge, specifically influencing the behavior of others. However, it is critical to evaluate the importance of additional aspects beyond the superficial such as who are the influencers, rather elements such as the content or nature of what is being discussed. Resultantly to trends of content, nature, and volume of what is being discussed in the online arena., people’s behavior regarding investments, specifically within Cryptocurrencies, are very possibly subjected to the influence of others, leading to rises and falls in coin valuation.
Aicha Bouichou, Soufiane Mezroui, Ahmed El Oualkadi
The security of the Ethereum Smart contracts constitutes the most important step toward securing the whole blockchain since it is opensource and anyone can write and deploy malicious contracts and make profits from doing so. The immutable aspect of the blockchain makes it hard to roll back malicious codes to restore the state of the EVM. In this paper, we propose a taxonomy for the vulnerabilities of smart contracts written in solidity language. We also proceed with some simple simulations of some attacks and errors on smart contracts and we demonstrate how these vulnerabilities can tamper with the state of the Ethereum blockchain.
The General Purpose Atomic Crosschain Transaction protocol allows composable programming across multiple Ethereum blockchains. It allows for inter-contract and inter-blockchain function calls that are both synchronous and atomic: if one part fails, the whole call execution tree of function calls is rolled back. The protocol operates on existing Ethereum blockchains without modification. It works for both public permissioned and consortium blockchains. Additionally, the protocol is expected to work across heterogeneous blockchains other than Ethereum. This paper describes the protocol, analyses it in terms of Gas usage and Finalised Block Periods for three scenarios: reading a value from one blockchain to another, writing a value from one blockchain to another, and a trade finance system involving five contracts on five blockchains with a complex call execution tree, and provides an initial security analysis that shows that the protocol has Safety and Liveness properties.
Abdelaziz Elbaghdadi, Soufiane Mezroui, Ahmed El Oualkadi
The cryptocurrency is the first implementation of blockchain technology. This technology provides a set of tracks and innovation in scientific research, such as use of data either to detect anomalies either to predict price in the Bitcoin and the Ethereum. Furthermore, the blockchain technology provide a set of technique to automate the business process. This chapter presents a review of some research works related to cryptocurrency. A model with a KNN algorithm is proposed to detect illicit transaction. The proposed model uses both the elliptic dataset and KNN algorithm to detect illicit transaction. Furthermore, the elliptic dataset contains 203,769 nodes and 234,355 edges; it allows to classify the data into three classes: illicit, licit, or unknown. Each node has associated 166 features. The first 94 features represent local information about the transaction. The remaining 72 features are called aggregated features. The accuracy exceeded 90% with k=2 and k=4, the recall reaches 56% with k=3, and the precision reaches 78% with k=4.
Mirko Zichichi, Stefano Ferretti, Gabriele D’Angelo, Victor Rodrı́guez-Doncel
This paper presents an architecture of a Personal Information Management System, in which individuals can define the access to their personal data by means of smart contracts. These smart contracts, running on the Ethereum blockchain, implement access control lists and grant immutability, traceability and verifiability of the references to personal data, which is stored itself in a (possibly distributed) file system. A distributed authorization mechanism is devised, where trust from multiple network nodes is necessary to grant the access to the data. To this aim, two possible alternatives are described: a Secret Sharing scheme and Threshold Proxy Re-Encryption scheme. The performance of these alternatives is experimentally compared in terms of execution time. Threshold Proxy Re- Encryption appears to be faster in different scenarios, in particular when increasing message size, number of nodes and the threshold value, i.e. number of nodes needed to grant the data disclosure.
Filipe Martins, David R. Matos, Miguel L. Pardal, Miguel Correia
Blockchain systems allow storing digital assets in a tamper-proof, consensus-based, append-only ledger in a decentralized fashion, where no single party has full control. A blockchain is an immutable, append-only, log of transactions. Unfortunately, in some cases there is the need to undo transactions that result from intrusions, e.g., when the private keys of a wallet are stolen, when one of the transaction participants does not comply with what was agreed upon, or when smart contract vulnerabilities are exploited by attackers. There are also accidental scenarios, e.g., when private keys are lost leaving the associated digital assets inaccessible. Although there have been a few proposals which allow modifications to the blockchain, they break the basic guarantees they are supposed to provide. We propose an approach for wallet owners to recover from attacks against their digital assets and accidental loss, while still assuring fundamental properties of the blockchain technology. We implemented the mechanism for Ethereum / EVM.
The present study is on the five cryptocurrency daily mean return time series linearity dynamics during the Covid-19 period. These cryptocurrencies were chosen based on their influence on the market, primarily driven by its market capitalisation. Tether is included as the most important stable coin on the market, nominally pegged to the U.S. dollar (USD). The reason to investigate it is that there are some inconsistencies in its behaviour as opposed to the other four cryptocurrencies. This study found that the behaviour of Tether cryptocurrency daily average return time series pattern is highly nonlinear and chaotic in nature, whereas the other four cryptocurrencies (namely Bitcoin, Ethereum, XRP and Bitcoin Cash) daily average return time series were found to be linear in nature. To further study Tether’s nonlinear time series rich dynamics, this study deployed one category of the regime switching models popularly known as the threshold regressions. The study estimates fairly suggest that both the threshold autoregression (TAR) and smooth transition autoregressive (STAR) models with lag 1 are adequate to capture the rich nonlinear and chaotic dynamics of Tether’s daily average return time series.
Rana Mahmoud Abdou, Hamdy Mahmoud Kadous, Ahmed Elsayed Hamdallah
The rapid development of cryptocurrencies has attracted the attention of investors, speculators, regulators, and academics in recent years. A large amount of research has been devoted to the pricing mechanisms of cryptocurrency markets, the drivers of volatility and the diversification potential of cryptocurrencies. (Kurka, 2019, P.38). bitcoin is the best-known cryptocurrency which currently holds the largest market capitalization and is regarded as a standard example of a cryptocurrency.( Jaywant, 2019 , P.147) bitcoin has emerged as the most popular virtual currency, and maintains the greatest share ahead of its competitors; the Ethereum, Ripple, Litecoin and bitcoin Cash. (Vardar & Aydogan , 2019 , P.2 )جذب التطور السريع للعملات المشفرة انتباه المستثمرين والمضاربين والمنظمين والأکاديميين في السنوات الأخيرة. تم تخصيص قدر کبير من الأبحاث لآليات التسعير الخاصة بأسواق العملات المشفرة ، ومحرکات التقلب وإمکانية التنويع في العملات المشفرة. عملة البيتکوين هي العملة المشفرة الأکثر شهرة والتي تمتلک حاليًا أکبر قيمة سوقية وتعتبر مثالًا قياسيًا للعملة المشفرة. برزت عملة البيتکوين باعتبارها العملة الافتراضية الأکثر شعبية ، وتحتفظ بأکبر حصة في المستقبل من منافسيها) الايثيرم ، الريبل ، اليتکوين والبيتکوين کاش).
The implementation of an electronic voting (e-voting) system which has begun to be widely applied in place of traditional electoral systems, still has a major problem in the level of trust results. E-voting systems are very vulnerable to manipulation issues, such as changes in election results due to hacking or by the electoral system maker. Centralized systems in a network result in data sources coming from one party having the right to store and to manage data sources. The issue of trust caused by a centralized data distribution system can be overcome by spreading data in a system network. Blockchain is a distributed ledger, where every party in the network has the same data source, and it has a powerful characteristic known as immutability which is very suitable for e-voting system. This research proposed a blockchain based e-voting system with Ethereum and metamask. We show that the proposed e-voting system fulfills six basic principles of an election system, namely secret ballot, one-man one-vote, voter eligibility, transparency, votes accurately, recorded and counted, and reliability. Furthermore, the performance evaluation of the e-voting system shows that the slow gas price option gives the lowest gas price per second result, i.e. the best trade-off.