Consensus is one of the key problems in blockchains. There are many articles analyzing the performance of threat models for blockchains. But the network stability seems lack of attention, which in fact affects the blockchain performance. This paper studies the performance of a well adopted consensus algorithm, Raft, in networks with non-negligible packet loss rate. In particular, we propose a simple but accurate analytical model to analyze the distributed network split probability. At a given time, we explicitly present the network split probability as a function of the network size, the packet loss rate, and the election timeout period. To validate our analysis, we implement a Raft simulator and the simulation results coincide with the analytical results. With the proposed model, one can predict the network split time and probability in theory and optimize the parameters in Raft consensus algorithm.
Halil Ibrahim Ozercan, Atalay Mert Ileri, Erman Ayday, Can Alkan
Genomics data introduce a substantial computational burden as well as data privacy and ownership issues. Data sets generated by high-throughput sequencing platforms require immense amounts of computational resources to align to reference genomes and to call and annotate genomic variants. This problem is even more pronounced if reanalysis is needed for new versions of reference genomes, which may impose high loads to existing computational infrastructures. Additionally, after the compute-intensive analyses are completed, the results are either kept in centralized repositories with access control, or distributed among stakeholders using standard file transfer protocols. This imposes two main problems: (1) Centralized servers become gatekeepers of the data, essentially acting as an unnecessary mediator between the actual data owners and data users; and (2) servers may create single points of failure both in terms of service availability and data privacy. Therefore, there is a need for secure and decentralized platforms for data distribution with user-level data governance. A new technology, blockchain, may help ameliorate some of these problems. In broad terms, the blockchain technology enables decentralized, immutable, incorruptible public ledgers. In this Perspective, we aim to introduce current developments toward using blockchain to address several problems in omics, and to provide an outlook of possible future implications of the blockchain technology to life sciences.
Open access
Blockchain Technology Applications and Security
Nanocluster Synthesis and Applications
Innovative Microfluidic and Catalytic Techniques Innovation
We compute and compare profitabilities of stubborn mining strategies that are variations of selfish mining. These are deviant mining strategies violating Bitcoin's network protocol rules. We apply the foundational set-up from our previous companion article on the profitability of selfish mining, and the new martingale techniques to get a closed-form computation for the revenue ratio, which is the correct benchmark for profitability. Catalan numbers and Catalan distributions appear in the closed-form computations. This marks the first appearance of Catalan numbers in the Mathematics of the Bitcoin protocol.
Traditional centralized energy systems have the disadvantages of difficult management and insufficient incentives. Blockchain is an emerging technology, which can be utilized in energy systems to enhance their management and control. Integrating token economy and blockchain technology, token economic systems in energy possess the characteristics of strong incentives and low cost, facilitating integrating renewable energy and demand side management, and providing guarantees for improving energy efficiency and reducing emission. This article describes the concept and functionality of token economics, and then analyzes the feasibility of applying token economics in the energy systems, and finally discuss the applications of token economics with an example in integrated energy systems.
Prateesh Goyal, Ravi Netravali, Mohammad Alizadeh, Hari Balakrishnan
Prior research has proposed technical solutions to use peer-to-peer (P2P) content delivery to serve Internet video, showing that it can reduce costs to content providers. Yet, such methods have not become widespread except for a few niche instances. An important challenge is incentivization: what tangible benefits does P2P content delivery offer users who bring resources to the table? In this paper, we ask whether monetary incentives can help attract peers in P2P content delivery systems. We commissioned a professional survey of people around theUnited States to answer several relevant questions. We found that 51% of the 876 respondents--substantially larger than our expectations--answered "yes" to whether they would participate for suitable financial incentives. Encouraged by the results of the survey, we propose Gringotts, a system to structure incentives and securely incorporate P2P delivery into content delivery systems. Gringotts provides a novel Proof of Delivery mechanism that allows content providers to verify correct delivery of their files, and shows how to use cryptocurrency to pay peers while guarding against liars and Sybil attacks.
Aug 2, 2018·Jan RĂŒth, Torsten Zimmermann, Konrad Wolsing, and Oliver Hohlfeld. 2018. Digging into Browser-based Crypto Mining. In IMC '18: Internet Measurement Conference, October 31-November 2, 2018, Boston, MA, USA. ACM, New York, NY, USA, 7 pages
Jan RĂŒth, Torsten Zimmermann, Konrad Wolsing, Oliver Hohlfeld
Mining is the foundation of blockchain-based cryptocurrencies such as Bitcoin rewarding the miner for finding blocks for new transactions. The Monero currency enables mining with standard hardware in contrast to special hardware (ASICs) as often used in Bitcoin, paving the way for in-browser mining as a new revenue model for website operators. In this work, we study the prevalence of this new phenomenon. We identify and classify mining websites in 138M domains and present a new fingerprinting method which finds up to a factor of 5.7 more miners than publicly available block lists. Our work identifies and dissects Coinhive as the major browser-mining stakeholder. Further, we present a new method to associate mined blocks in the Monero blockchain to mining pools and uncover that Coinhive currently contributes 1.18% of mined blocks having turned over 1293 Moneros in June 2018.
Sierra Ison, Jeremy Hills, Cherie W. Morris, Selina M. Stead
Marine Protected Areas (MPA) are mostly studied from an environmental context. A review of available information identified a lack of knowledge in sustainable mechanisms to finance MPA networks. At the United Nations Ocean Conference in 2017, Fiji reaffirmed its voluntary commitment to make 30% of its inshore and offshore marine area MPAs by 2020 under Sustainable Development Goal 14. The work presented here uses empirical data to explore potential benefits from selected community-based MPAs to recipient local stakeholders. A Willingness to Pay (WTP) and Willingness to Contribute Time (WtCT) method was used to explore the extent to which bottom-up governance systems represent a potential financing mechanism of a MPA network. Results of 115 interviews concluded that proximity to a fishing market, dependence on marine resources, food security, income and international commitments were significant variables influencing stakeholder's WTP and WtCT to manage a MPA. We argue that there is a discrepancy between WtCT and WTP driven by income constraints. Thus, by using WTP and WtCT to support financing of a MPA network, a Provincial Trust Fund (PTF) could promote an equitable and benefits-based contribution. Equally important, a PTF has a polycentric and decentralized governance model, which endorses sustainable management of traditional fishing communities. The conclusions provide insight into a bottom-up approach for long-term financial sustainability of Fiji's national MPA commitments.
Open access
Economic and Environmental Valuation
Coral and Marine Ecosystems Studies
Conservation, Biodiversity, and Resource Management
Jialiang Chang, Bo Gao, Hao Xiao, Jun Sun · 6 authors
Ethereum smart contracts are an innovation built on top of the blockchain technology, which provides a platform for automatically executing contracts in an anonymous, distributed, and trusted way. The problem is magnified by the fact that smart contracts, unlike ordinary programs, cannot be patched easily once deployed. It is important for smart contracts to be checked against potential vulnerabilities. In this work, we propose an alternative approach to automatically identify critical program paths (with multiple function calls including inter-contract function calls) in a smart contract, rank the paths according to their criticalness, discard them if they are infeasible or otherwise present them with user friendly warnings for user inspection. We identify paths which involve monetary transaction as critical paths, and prioritize those which potentially violate important properties. For scalability, symbolic execution techniques are only applied to top ranked critical paths. Our approach has been implemented in a tool called sCompile, which has been applied to 36,099 smart contracts. The experiment results show that sCompile is efficient, i.e., 5 seconds on average for one smart contract. Furthermore, we show that many known vulnerabilities can be captured if user inspects as few as 10 program paths generated by sCompile. Lastly, sCompile discovered 224 unknown vulnerabilities with a false positive rate of 15.4% before user inspection.
This paper discusses the application of the blockchain technology to wireless communications, in particular, for enhancing the security of vehicular communications. The idea that the blockchain will become a key solution for ensuring security and data consistency has long been controversial, even in more traditional areas such as finance or real-estate, for example. In this paper, an analysis of the two opposing sides is put forward and a review of the key aspects that need further evolution to ensure the blockchain's survival is presented. In the context of vehicular communications existing blockchain applications are examined with focus on certificate and reputation management, and message forwarding promotion. In this scope, the future of the blockchain is debated with emphasis on the key limitations of public implementations.
... Recent years have shown a surge of interest from various enforcement agencies to remedy commercial behaviour exploiting the increasing information and power asymmetries between consumers and firms. What is particularly notable about this rise in attention is that enforcement actions demonstrate clear interactions between different legal fields that are traditionally applied and enforced in isolation. The present article will focus in particular on the growing interaction between competition, data protection, and consumer law. The Italian Competition, Communications and Data Protection Authority opened a joint âbig dataâ sector inquiry in May 2017 that not only aims to identify potential competition concerns but also to define âa regulatory framework able to foster competition in the markets of the digital economy, to protect privacy and consumers, and to promote pluralism within the digital ecosystemâ.1 The Bundeskartellamt (German competition authority) announced its preliminary assessment in the Facebook competition investigation in December 2017, reaching the view that Facebookâs collection and use of data from third-party sources is abusive. According to the Bundeskartellamt, Facebookâs terms of service violate data protection provisions and thereby constitute abuse of dominance under competition law as well.2 On the basis of its new competence in the area of consumer protection,3 the Bundeskartellamt also opened two sector inquiries into online price comparison websites and smart TVs in October and December 2017, respectively. The sector inquiry into comparison websites aims to uncover possible violations of consumer law and to identify possible deficits in the enforcement of consumer rights that so far mainly takes place in individual private court proceedings.4 The sector inquiry into smart TVs investigates how producers of smart TVs handle user data. In particular, the Bundeskartellamt is looking to clarify to what extent smart TV manufacturers collect, use and pass on personal data, and whether individuals are appropriately informed of these practices in the contract terms.5
Dimaz Ankaa Wijaya, Joseph K. Liu, Ron Steinfeld, Dongxi Liu
Monero is one of the privacy-preserving cryptocurrencies employing CryptoNote protocol. The privacy features in Monero are provided by cryptographic techniques such as linkable ring signature and one-time public key. Recent studies show that the majority of Monero inputs are traceable prior to mandatory RingCT transaction. After the RingCT was implemented, the problems were mitigated. We propose a novel attack to reduce the anonymity of Monero transactions or even to fully deanonymise the inputs. The proposed protocol can be launched in RingCT protocol and enables multiple attackers to collaborate without trusting each other. The attack scheme can be planted in the existing Monero services without extra fees and without putting the users' money at risk.
Current digital certification revocation systems are insufficient in the application scenario of multiple certification authorities (CAs), and it leads to a lack of mutual trust, access stability, and timeliness of data synchronization between CAs. We propose a decentralized digital certificate revocation system based on consortium blockchain technology with a secret sharing scheme. It can invalidate the digital certificate in special cases to protect the user's information and property security. Based on the characteristics of the decentralized consensus mechanism, consortium blockchain technology is the core technology of the system. The scheme achieves collaborative management of digital certificate revocation lists (CRLs) by multiple CAs, and introduces secret sharing scheme, further safeguarding the reliability of the maintenance process, and then the online certificate status protocol (OCSP) can be developed based on this system. This system is security, effective, and cannot be tampered. Compared with the traditional revocation scheme, it achieves trusted and reliable CRL system above multiple CAs, which can provide new ideas for the way of digital certificate revocation and expand the application range of blockchain technology.
Innerhalb der letzten Jahre wurden Blockchain-Technologien in vielen traditionellen Sektoren (z.B. im Finanzbereich) adaptiert. Dadurch wurden existierende Systeme neu ĂŒberdacht und ganzheitlich neuartige Systeme erfunden. Allerdings blieb wĂ€hrend dieser Zeit des raschen Fortschritts der Fokus stets auf der schnellen Produktentwicklung, was zu vielen Sicherheitsproblemen gefĂŒhrt hat durch die mehrere hundert Millionen von USD gestohlen oder verloren wurden. Nahezu alle derzeitig öffentlichen Blockchains bieten keine formale Semantik oder formales Framework zur Verifizierung von Smart-Contract-Code. Diese Arbeit prĂ€sentiert eine neuartige Semantik fĂŒr Smart-Contract-Interaktionen und eine state-of-the-art Implementierung eines smart-contract-basierenden Investmentfonds fĂŒr die Ethereum Blockchain. Der Fokus liegt darauf, eine formale Semantik fĂŒr Smart Contracts mit dem tatsĂ€chlichen, wirtschaftlichen Anwendungsfall eines Investmentfonds zu verbinden. Genauer gesagt, die eingefĂŒhrte Semantik bietet einen neuartigen Denkansatz dadurch, dass sie Smart Contract Interaktionen und nicht einzelne Smart-Contract-AusfĂŒhrungen in den Mittelpunkt stellt. Die Blockchain wird durch einen Global State reprĂ€sentiert, auf welchem komplexe Transaktionen durch eine Big-Step-Semantik modelliert werden können. Der im Laufe dieser Arbeit entwickelte Investmentfonds ERCFund macht es möglich, in ein aktiv verwaltetes Portfolio von ERC20-Tokens und Ether zu investieren. Dies wird realisiert durch Tokens, welche als Anteil des Investmentfonds genutzt werden und je nach Bedarf gemĂŒnzt und vernichtet werden können. AuĂerdem unterstĂŒtzt die Software mehrere fortgeschrittene Funktionen, wie z.B. Cold-Wallet-Support und Multi-Signature-Schutz durch Off-Chain-Signaturen. Wir zeigen, dass die eingefĂŒhrte Semantik in einer realen, geschĂ€ftlichen Situation anwendbar ist, indem wir eine wesentliche Sicherheitsfunktion des Investmentfonds adaptieren und formal beweisen.
Domhnall Carlin, Philip OrKane, Sakir Sezer, Jonah Burgess
With the rise in worth and popularity of cryptocurrencies, a new opportunity for criminal gain is being exploited and with little currently offered in the way of defence. The cost of mining (i.e., earning cryptocurrency through CPU-intensive calculations that underpin the blockchain technology) can be prohibitively expensive, with hardware costs and electrical overheads previously offering a loss compared to the cryptocurrency gained. Off-loading these costs along a distributed network of machines via malware offers an instantly profitable scenario, though standard Anti-virus (AV) products offer some defences against file-based threats. However, newer fileless malicious attacks, occurring through the browser on seemingly legitimate websites, can easily evade detection and surreptitiously engage the victim machine in computationally-expensive cryptomining (cryptojacking). With no current academic literature on the dynamic opcode analysis of cryptomining, to the best of our knowledge, we present the first such experimental study. Indeed, this is the first such work presenting opcode analysis on non-executable files. Our results show that browser-based cryptomining within our dataset can be detected by dynamic opcode analysis, with accuracies of up to 100%. Further to this, our model can distinguish between cryptomining sites, weaponized benign sites, de-weaponized cryptomining sites and real world benign sites. As it is process-based, our technique offers an opportunity to rapidly detect, prevent and mitigate such attacks, a novel contribution which should encourage further future work.
Risk and Information System Control Framework in business includes the methods and processes to manage risks and seize opportunities which involve identifying particular risk events relevant to the objectives, assessing them in terms of likelihood and magnitude of impact, determining a response strategy, and monitoring progress. In order to provide better support for the backtracking, traceability, irreversibility, and credible requirements of risk registration table data in the framework, this paper proposes a blockchain-based risk and information system control framework. A risk association tree is designed for combining summarized risk item ledgers with risk assessment ledgers and risk response ledgers based on the Merkle Tree. Three proposed smart contracts are used in risk identification, risk assessment, risk response and mitigation, and risk and control monitoring and reporting processes. We implement a prototype for this framework.
The article discusses the nature of law in cyberspace. Topics discussed include distinction between regulation as infringement of private autonomy and regulation as a collaborative enterprise; blockchain regulatory conundrum; and neoliberal market-complementing regulation. Also being discussed is the regulation for economic efficiency and consumer choice.
The objective of this paper is to examine whether the level of fiscal decentralization of a country is a relevant variable to explain public investment in innovation (measured as the share of research and development (R&D) spending in total government budget) and the intensity of basic research within the public R&D bundle. To assess the effects of decentralization, we present a theoretical model where a 'benevolent government' invests in R&D aiming at maximizing net income available in the country (central government) or in the respective region (subnational government), states compete to attract capital investment, and R&D results are subject to interregional knowledge spillovers. According to the model, decentralization leads to a lower share of basic research in government innovation spending. The impact on total R&D is ambiguous, although it tends to be negative. The conclusions of the model are tested through an empirical analysis using country aggregate data. Confirming the predictions of the model, we find evidence that expenditure decentralization leads to lower intensity of basic research within public R&D, and that both types of decentralization negatively affect the size of innovation spending. Our findings suggest that deepening fiscal decentralization should be considered along with measures to compensate for innovation spending decrease, and that the central government should play a greater role in financing or carrying out basic research.
The vision for ARTiFACTS sprang from the realization that distributed ledger technology/blockchain technology could be applied directly to scholarly communications. Blockchain fits our current system of citation currency. As Eugene Garfield said decades ago, âThe Mertonian description of normal science describes citations as the currency of science. Scientists make payments, in the form of citations, to their preceptorsâ. To work properly, scientists must be able to create, claim ownership, share novel works, and assign proper attribution to prior work at all phases of their research. However, the existing process of disseminating research and scientific discoveries is skewed towards published articles. Communication, sharing, and the ability to give or receive attribution are delayed far downstream - oftentimes several years â from the actual time when discoveries are made and formally communicated. Distributed ledger technology can deliver transformative value and efficiency in facilitating real-time sharing of the outputs of each step of the research process while providing comprehensive and immutable, break-proof attribution and linking for all relevant research artifacts. Ultimately, this technology will empower the scientific and scholarly communities to affect positive change. This paper briefly discusses some of the early learnings from their recent introduction of the ARTiFACTS system.
Jonathan Coignard, Eric Munsing, Jason MacDonald, Jonathan Mather
The increased penetration of Distributed Energy Resources (DERs) on the distribution network creates local challenges in balancing consumption and generation. To coordinate the roll-out and the operation of DERs, distribution-level energy markets have been proposed, but there are currently few tools for simulating the operation of DERs in these proposed markets. We present a framework which utilizes a grid co- simulation platform (Mosaik) to simulation DER operation, while simulating market clearing operations with a blockchain network (Ethereum). The use of blockchains, an emerging technology for decentralized computing and data storage, allows us to model secure decentralized execution of market clearing functions and payment processes. By unifying simulation of market clearing rules and the physical grid, we are able to ensure that economic incentives are aligned with physical constraints, helping facilitate the development of more effective distributed energy markets. We demonstrate the use of this new simulation platform on a small feeder, for which a market mechanism to incentivize DER integration is explored.
This paper offers an overview of the highlights of the NFAIS Conference, Blockchain for Scholarly Publishing, that was held in Alexandria, VA from May 15â16, 2018. The goal of the conference was to take a close look at the initiatives that have emerged as a result of the increasing global acceptance of blockchain technology. This technology, chiefly known as the foundation of Bitcoin and originally introduced as a means of securely managing cryptocurrency, has proven to have practical applications beyond finance. The basic technology is that of a distributed ledger and it is being broadly-adopted by multiple industries, including the scholarly publishing community. The capabilities of this new technology are prompting a direct exchange among stakeholders, as blockchain promises a more structured, decentralized, and immutably secure approach that has the potential to significantly impact researcher workflows - from data collection to peer review to access and published work. The technology inspires passion - there are those who believe that it will ultimately transform our lives while others are completely skeptical. The NFAIS conference provided a look at both sides of the coin (no pun intended).
Since Bitcoinâs launch in early 2009, the industrial and academic interest in Blockchain and other cryptocurrencies have grown rapidly. Blockchains have been applied in many areas outside of finance such as healthcare, commerce and judiciary already. This technology promotes the creation of a decentralized environment where transactions and data are not under the control of any third-party organization. Blockchain is a fundamentally new technology that could revolutionize the future of transaction-based exchanges. Extensive research is being done in order to implement this technology various sectors. Blockchain technology comes with an edge of inbuilt auditability, trust and transfer of value which also makes it irresistible. \nThis work explores an agent based Blockchain-based Education System through mathematical modeling and simulation tools. The model is constructed to explore how Blockchain technology can be used to verify credit score of students, identify the occurrence and prevention of potential attacks. Along with technical characteristics of Bitcoin and Blockchain; cost, time and behavioural considerations of the system are also made. This is followed by analysing of the number of transactions, size of blockchain, network efficiency, cost analysis of the system along with the network efficiency. The proposed model, based on the blockchain technology shifts the education grading and credit rewarding system from the analog and physical world into a globally efficient, transparent and universal version. The work contributes a foundation for advancing current understanding of blockchain systems, and to further the development of simulation models of blockchains.
The new technological advances have brought a revolution on how economic agents interact with society and markets. Nowadays, the use of virtual currencies is more frequent in the financial transactions and bitcoin has been defined as the most important world cryptocurrency due to its high market capitalization and its technological infrastructure. Several studies have been conducted to discuss bitcoin advantages and disadvantages; however, few papers in literature have examined its connection and influence on the stock market. The objective of this paper is precisely cover this gap. Firstly, by providing tools and concepts to understand bitcoinâs dynamic, and then determining its relationship with stock market indexes. In that context, this manuscript examines the definition and function of bitcoin in the global world and its presence in Ecuador. Besides, exploratory and visual analyses are provided using the evolution of bitcoin and other market indexes. Finally, a linear correlation is computed between bitcoin, other cryptocurrencies, stock exchange indexes and commodities. The results in this study, employing visual and statistical analyses, demonstrated that bitcoin has: a strong relationship with other cryptocurrencies; a lineal correlation, not as strong as the previous one, with the main stock market indexes; and no linear correlation with commodities.
BACKGROUND & OBJECTIVES: Numerous studies have highlighted the regressive and immiserating impact of out-of-pocket (OOP) health spending in India. However, most of these studies have explored this issue at the national or up to the State level, with an associated risk of overlooking intra-State diversities in the health system and health-seeking behaviour and their implication on the financial burden of healthcare. This study was aimed to address this issue by analyzing district level diversities in inequity, financial burden and impoverishing impact of OOP health spending. METHODS: A household survey of 62,335 individuals from 12,134 households, covering eight districts across three States, namely Gujarat, Haryana and Rajasthan was conducted during 2014-2015. Other than general household characteristics, the survey collected information on household OOP [sum total of expenditure on doctor consultation, drugs, diagnostic tests etc. on inpatient depatment (IPD), outpatient depatment (OPD) or chronic ailments] and household monthly consumption expenditure [sum total of monthly expenditure on food, clothing, education, healthcare (OOP) and others]. Gini index of consumption expenditure, concentration index and Kakwani index (KI) of progressivity of OOP, catastrophic burden (at 20% threshold) and poverty impact (using district-level poverty thresholds) were computed, for these eight districts using the survey data. The concentration curve (of OOP expenditure) and Lorenz curve (of consumption expenditure) for the eight districts were also drawn. RESULTS: The distribution of OOP was found to be regressive in all the districts, with significant inter-district variations in equity parameters within a State (KI ranges from -0.062 to -0.353). Chhota Udepur, the only tribal district within the sample was found to have the most regressive distribution (KI of -0.353) of OOP. Furthermore, the economic burden of OOP was more pronounced among the rural sample (CB of 19.2% and IM of 8.9%) compared to the urban sample (CB of 9.4% and IM of 3.7%). INTERPRETATION & CONCLUSIONS: The results indicate that greater decentralized planning taking into account district-level health financing patterns could be an effective way to tackle inequity and financial vulnerability emerging out of OOP expenses on healthcare.
Capital constraints exist in many supply chains. We examine a low carbon distribution channel that consists of a manufacturer and a retailer, in which the retailer is constrained by capital. The retailer can be financed by bank credit from a competitive bank market. A Stackelberg model is developed to analyze the integrated decision-making process of ordering, financing, and emission reduction. By comparing the decentralized and centralized channels, we obtain that the manufacturerâs green technology investment should be linearly proportional to the retailerâs order quantity in both channels. Thus, a large order quantity leads to increased efforts to reduce emissions. Results further show that the centralized channel in some cases has fewer emissions and can generate more profits for the whole supply chain compared with the decentralized channel. We therefore propose a revenue sharing contract with a function form to coordinate the distribution channel. When the government allocates appropriate quotas to the supply chain, high carbon price can benefit the environment and supply chain efficiency.