As Electric Vehicles (EVs) are becoming widely available, their secure management is crucial to fully enable their potential. For instance, for convenient charging, they may require quick authentication with the charging stations while they are on the go. As charging is frequently needed, exposing one's charging frequency to the stations may risk the exposure of privacy for the EV driver. Therefore, a mechanism is needed to hide EV information. In this paper, we propose using zero-knowledge proofs to achieve this goal. While zero-knowledge proofs can provide anonymous authentication, they require computation for generation of witnesses. Therefore, we assess the overhead of generating a witness and proof computation at the resource constrained on-board units (OBUs) which are deployed on EVs that utilize wireless communications for scheduling. The results indicate that computation overhead is minimal and can be delployed on resource contrained devices.
Matteo Romiti, Aljosha Judmayer, Alexei Zamyatin, Bernhard Haslhofer
Dataset retrieved and used with the code hosted here for this paper published at WEIS 2019 Abstract Miners play a key role in cryptocurrencies such as Bitcoin: they invest substantial computational resources in processing transactions and minting new currency units. It is well known that an attacker controlling more than half of the network’s mining power could manipulate the state of the system at will. While the influence of large mining pools appears evenly split, the actual distribution of mining power within these pools and their economic relationships with other actors remain undisclosed. To this end, we conduct the first in-depth analysis of mining reward distribution within three of the four largest Bitcoin mining pools and examine their cross-pool economic relationships. Our results suggest that individual miners are simultaneously operating across all three pools and that in each analyzed pool a small number of actors (≤ 20) receives over 50% of all BTC payouts. While the extent of an operator’s control over the resources of a mining pool remains an open debate, our findings are in line with previous research, pointing out centralization tendencies in large mining pools and cryptocurrencies in general
Zhenyu Zhou, Bingchen Wang, Mianxiong Dong, Kaoru Ota
Smart grid has emerged as a successful application of cyber-physical systems in the energy sector. Among numerous key technologies of the smart grid, vehicle-to-grid (V2G) provides a promising solution to reduce the level of demand-supply mismatch by leveraging the bidirectional energy-trading capabilities of electric vehicles. In this paper, we propose a secure and efficient V2G energy trading framework by exploring blockchain, contract theory, and edge computing. First, we develop a consortium blockchain-based secure energy trading mechanism for V2G. Then, we consider the information asymmetry scenario, and propose an efficient incentive mechanism based on contract theory. The social welfare optimization problem falls into the category of difference of convex programming and is solved by using the iterative convex-concave procedure algorithm. Next, edge computing has been incorporated to improve the successful probability of block creation. The computational resource allocation problem is modeled as a two-stage: 1) Stackelberg leader-follower game and 2) the optimal strategies are obtained by using the backward induction approach. Finally, the performance of the proposed framework is validated via numerical results and theoretical analysis.
We present Harvey, an industrial greybox fuzzer for smart contracts, which are programs managing accounts on a blockchain. Greybox fuzzing is a lightweight test-generation approach that effectively detects bugs and security vulnerabilities. However, greybox fuzzers randomly mutate program inputs to exercise new paths; this makes it challenging to cover code that is guarded by narrow checks, which are satisfied by no more than a few input values. Moreover, most real-world smart contracts transition through many different states during their lifetime, e.g., for every bid in an auction. To explore these states and thereby detect deep vulnerabilities, a greybox fuzzer would need to generate sequences of contract transactions, e.g., by creating bids from multiple users, while at the same time keeping the search space and test suite tractable. In this experience paper, we explain how Harvey alleviates both challenges with two key fuzzing techniques and distill the main lessons learned. First, Harvey extends standard greybox fuzzing with a method for predicting new inputs that are more likely to cover new paths or reveal vulnerabilities in smart contracts. Second, it fuzzes transaction sequences in a targeted and demand-driven way. We have evaluated our approach on 27 real-world contracts. Our experiments show that the underlying techniques significantly increase Harvey's effectiveness in achieving high coverage and detecting vulnerabilities, in most cases orders-of-magnitude faster; they also reveal new insights about contract code.
Purpose This paper aims to encourage the study of blockchain technology from an operations and supply chain management (OSCM) perspective, identifying potential areas of application, and to provide an agenda for future research. Design/methodology/approach An explanation and analysis of blockchain technology is provided to identify implications for the field of OSCM. Findings The hype around the opportunities that digital ledger technologies offer is high. For OSCM, a myriad of ways in which blockchain could transform practice are identified, including enhancing product safety and security; improving quality management; reducing illegal counterfeiting; improving sustainable supply chain management; advancing inventory management and replenishment; reducing the need for intermediaries; impacting new product design and development; and reducing the cost of supply chain transactions. The immature state of practice and research surrounding blockchain means there is an opportunity for OSCM researchers to study the technology in its early stages and shape its adoption. Research limitations/implications The paper provides a platform for new research that addresses gaps in knowledge and advances the field of OSCM. A research agenda is developed around six key themes. Practical implications There are many opportunities for organisations to obtain an advantage by making use of blockchain technology ahead of the competition, enabling them to enhance their market position. But it is important that managers examine the characteristics of their products, services and supply chains to determine whether they need or would benefit sufficiently from the adoption of blockchain. Moreover, it is important that organisations build human capital expertise that allows them to develop, implement and exploit applications of this technology to maximum reward. Originality/value This is one of the first papers in a leading international OSCM journal to analyse blockchain technology, thereby complementing a recent article on digital supply chains that omitted blockchain.
The digital competence is necessary for 21st century living, but from several countries survey, a large number of people still have insufficient digital competence. Moreover, from literature study found three problems of today cooperative education information system, (1) lack of information sharing among university community, (2) lack of connect information to public, and (3) lack of enhancing 21st century learning skill. This paper proposes a process design of cooperative education management system by using the integration of cooperative education, E-Portfolio, digital competence framework 2.0, cloud computing technology, and blockchain technology. These processes make result of digital competence assessment credible and share to open digital labor market finally.
Purpose of the study. The first goal of the study is a comparative analysis of the models of the accounting system of the stock market operating on the territory of the Russia, in particular, the model of the distributed accounting system and the model of the centralized accounting with the use of the central depository are considered. The second goal is to apply the distributed ledger technology in the development of a new model for the stock market accounting system. The goals are conditioned by the growing interest to the technology and similarity of its internal processes with the system of accounting of digital assets. The needs in optimization of the existing accounting system, bringing the system to the logical centralization are revealed. The application of distributed ledger technology for the purpose of unification of depository accounting systems is proposed. The analysis of efficiency of the given models is carried out and the criteria of efficiency estimation of each model are revealed. Materials and methods. For carrying out the research the works of description of register system genesis of stock market in Russia were applied. Works of Russian and foreign researchers in the field of influence of technology of distributed registers on accounting system and business processes of organizations are studied. The methodology for comparing models was the approach to the development of highly specialized evaluation criteria that meet the needs of the largest number of stock market participants. Results. Evaluation criteria were developed, on the basis of which the comparison of the existing models of the accounting system of stock market and the projected model on the distributed ledger technology was carried out. The needs for optimization of the existing accounting system of Russia, bring the system to the logical centralization of interaction of elements are revealed. Suggestions for the use of distributed ledger technology in order to unite the register systems of obligations have been developed The variety of elements of the accounting system of the Russian stock market was determined a large number of indicators used in comparisons of models, as well as a variety of approaches, both to the construction of the indicators themselves and to the collection of data to ensure their calculation and comparison. Conclusion. According to the results of the research it was determined that the decentralized model of the stock market accounting system on the distributed ledger technology in comparison with the classic model reduces the transaction cost of obligation right accounting operations, optimizes the complexity of the processes of interaction between the elements of the system, such as depositories and registrars, increases the transparency of the stock market, the processes of the transition of assets rights, due to which the liquidity of such assets and the increases investors interest. Decentralized model standardizes the of communication data, which has a positive effect on the indicators of information systems of participants. In comparison with the centralized model, the decentralized model eliminates the central depository transaction commission, eliminates monopolization to choose the direction of stock market depository accounting system development. Finally, the positive influence of the decentralized model on the stock market as a whole was revealed. The resulting form of relations will reduce the main cost indicators of the accounting system elements, such as transaction costs, the cost of support and development of information systems, the number of necessary formats for the application of interaction with counterparties.
Vítor Manuel Araújo da Fonseca, Manuel A. R. da Fonseca
This article’s goal is to evaluate if the recent price behavior of Bitcoin can be characterized as a financial market “bubble”. To deal with this assessment, we adopt a statistical definition of a “bubble” derived from the efficient market hypothesis and we propose a simple method to test this proposition, based on the time-series model known as random walk. We analyze the data available for Bitcoin prices, together with an asset selected as benchmark, and perform statistical tests derived from simple regression equations. The main conclusion is that there is consistent evidence that that Bitcoin follows the pattern of a financial “bubble” – at least, such pattern is more evident in the case of Bitcoin than in the stock index used as benchmark.
[full article and abstract in Lithuanian; abstract in English] The main feature of the twenty-first century could be named as permanent transformation that covers all areas. Payments and money are developing and changing especially fast. Technological evolution and development have led to the emergence of new transactional techniques on the Internet, mobile phones, and credit cards. Various systems of payment / money transfer have considerably expanded payment options and possibilities. And such conditions have created opportunities for the emergence of a cryptocurrency. The purpose of the study is to investigate the cryptocurrency, its concept, advantages and disadvantages. Analysis of the scientific literature, systematization, comparison, interpretation and generalization of information research methods were used for the study. Evaluation of the reasons for the emergence of cryptocurrency let to generalise, that the process was mostly influenced by technological progress and the aspiration to find faster, cheaper and more confidential settlement tools. Cryptocurrency may be defined as digital money or property in electronical form. This currency may be characterized by properties of decentralization, uncontrollability and higher risk management. The most important advantages of using a cryptocurrency may be: the speed of settlements; cheaper financial services; additional investment opportunities. Disadvantages - unpredictable, fluctuating value; possible fraud cases; possibility to use cryptocurrency for illegal activities.
With the rapid development of communication technologies, the Internet of Things (IoT) is getting out of its infancy, into full maturity, and tends to be developed in an explosively rapid way, with more and more data transmitted and processed. As a result, the ability to manage devices deployed worldwide has been given more and advanced requirements in practical application performances. Most existing IoT platforms are highly centralized architectures, which suffer from various technical limitations, such as a cyber-attack and single point of failure. A new solution direction is essential to enhance data accessing, while regulating it with government mandates in privacy and security. In this paper, we propose an integrated IoT platform using blockchain technology to guarantee sensing data integrity. The aim of this platform is to afford the device owner a practical application that provides a comprehensive, immutable log and allows easy access to their devices deployed in different domains. It also provides characteristics of general IoT systems, allows for real-time monitoring, and control between the end user and device. The business logic of the application is defined by the smart contract, which contains rules and conditions. The proposed approach is backed by a proof of concept implementation in realistic IoT scenarios, utilizing Raspberry Pi devices and a permissioned network called Hyperledger Fabric. Lastly, a benchmark study using various performance metrics is made to highlight the significance of the proposed work. The analysis results indicate that the designed platform is suitable for the resource-constrained IoT architecture and is scalable to be extended in various IoT scenarios.
Recently, graph embedding techniques have been widely used in the analysis of various networks, but most of the existing embedding methods omit the network dynamics and the multiplicity of edges, so it is difficult to accurately describe the detailed characteristics of the transaction networks. Ethereum is a blockchain-based platform supporting smart contracts. The open nature of blockchain makes the transaction data on Ethereum completely public, and also brings unprecedented opportunities for the transaction network analysis. By taking the realistic rules and features of transaction networks into consideration, we first model the Ethereum transaction network as a Temporal Weighted Multidigraph (TWMDG), where each node is a unique Ethereum account and each edge represents a transaction weighted by amount and assigned with timestamp. Then we define the problem of Temporal Weighted Multidigraph Embedding (T-EDGE) by incorporating both temporal and weighted information of the edges, the purpose being to capture more comprehensive properties of dynamic transaction networks. To evaluate the effectiveness of the proposed embedding method, we conduct experiments of node classification on real-world transaction data collected from Ethereum. Experimental results demonstrate that T-EDGE outperforms baseline embedding methods, indicating that time-dependent walks and multiplicity characteristic of edges are informative and essential for time-sensitive transaction networks.
This paper presents a new framework, namely \emph{\onlay}, for scalable asynchronous distributed systems. In this framework, we propose a consensus protocol $L_φ$, which is based on the Lachesis protocol~\cite{lachesis01}. At the core of $L_φ$ protocol, it introduces to use layering algorithm to achieve practical Byzantine fault tolerance (pBFT) in leaderless asynchronous Directed Acyclic Graph (DAG). Further, we present new online layering algorithms for the evolutionary DAGs across the nodes. Our new protocol achieves determistic scalable consensus in asynchronous pBFT by using assigned layers and asynchronous partially ordered sets with logical time ordering instead of blockchains. The partial ordering produced by $L_φ$ is flexible but consistent across the distributed system of nodes. We then present the formal model of our layering-based consensus. The model is generalized that can be applied to abstract asynchronous DAG-based distributed systems.
Considering the critical influencing phenomena, the study explores the causal mechanism of influences, as well as how such process works that lead to shape the dominant implications of influences on local government Union Councils’ budgetary autonomy, leading to the impact on their local governance.The research reveals the fact that the effects of the influencing phenomena on the budgetary autonomy of Union Councils in Bangladesh are evident with varying degrees and dimensions, but the influences do not always collide with the budgetary autonomy of Union Councils there. The indicator-based empirical analysis reveals that the magnitude of influences is almost double than that of the budgetary autonomy of Union Councils in Bangladesh. Thus, the autonomy of Union Councils in their budgeting decisions is a concern in the study of decentralization and local governance in Bangladesh.Originality and significance:The research contributed in the literature stream of public administration, specifically in decentralization, local government finance as well as budgeting, and in local governance studies. The study findings to some extent substantiated the rationality of conditional national government transfers to the sub-national governments in Bangladesh. Beyond the general theoretical and practical significance of the study, its findings led to inviting a fundamental debate on the national-local tax base system and appreciated the fact that central hindrance towards effective functioning of the local government Union Councils in Bangladesh is the crisis of ownership and competence of UP representatives.
This paper is a progress report on our recent work on two applications that use Linked Data and Distributed Ledger technologies and aim to transform the Greek public sector into a decentralized, trusted, intelligent and linked organization. The first application is a re-engineering of Diavgeia, the Greek government portal for open and transparent public administration. The second application is Nomothesia, a new portal that we have built, which makes Greek legislation available on the Web as linked data to enable its effective use by citizens, legal professionals and software developers who would like to build new applications that utilize Greek legislation. The presented applications have been implemented without funding from any source and are available for free to any part of the Greek public sector that may want to use them. An important goal of this paper is to present the lessons learned from this effort.
Ηλίας Κουτσουπιάς, Philip Lazos, Foluso Ogunlana, Paolo Serafino
We study the strategic implications that arise from adding one extra option to the miners participating in the bitcoin protocol. We propose that when adding a block, miners also have the ability to pay forward an amount to be collected by the first miner who successfully extends their branch, giving them the power to influence the incentives for mining. We formulate a stochastic game for the study of such incentives and show that with this added option, smaller miners can guarantee that the best response of even substantially more powerful miners is to follow the expected behavior intended by the protocol designer.
User's digital identity information has privacy and security requirements. Privacy requirements include confidentiality of the identity information itself, anonymity of those who verify and consume a user's identity information and unlinkability of online transactions which involve a user's identity. Security requirements include correctness, ownership assurance and prevention of counterfeits of a user's identity information. Such privacy and security requirements, although conflicting, are critical for identity management systems enabling the exchange of users' identity information between different parties during the execution of online transactions. Addressing all such requirements, without a centralized party managing the identity exchange transactions, raises several challenges. This paper presents a decentralized protocol for privacy preserving exchange of users' identity information addressing such challenges. The proposed protocol leverages advances in blockchain and zero knowledge proof technologies, as the main building blocks. We provide prototype implementations of the main building blocks of the protocol and assess its performance and security.
The international experience of various countries of the world in the implementation, usage, and economic and legal status of cryptocurrency is compared in this research. The advantages and disadvantages of using cryptocurrency at the present stage of economic and scientific-technical development of Ukraine are considered. The results of the research of the awareness of market participants regarding the advantages and disadvantages of cryptocurrency and the presence of interest in the usage of cryptocurrency are given. The aim of this article is to study the possibilities of using cryptocurrency for economic development. The object of the research is the process of using cryptocurrency in the market in Ukraine, taking into account world experience. Practical implications. The results of a study of the demand for cryptocurrency in Ukraine. The research was conducted with the help of a questionnaire, as a result of which it was found out: the level of awareness of cryptocurrency; subjective perception of cryptocurrency; sources of awareness of cryptocurrency; the presence of the potential interest of Ukrainians in the acquisition of cryptocurrency. It was found what exactly Ukrainians consider the main advantages and disadvantages of cryptocurrency. Value/originality. Cryptocurrency as a means of payment and a type of electronic money is found in the most countries of the world in the “grey” zone, and regulators, if not prohibit, then at least do not recommend citizens to invest in such assets. However, the state of science and technology development of blockchain technologies, which are the basis of cryptocurrency, and the state of demand for cryptocurrency in the Ukrainian market are ready to use cryptocurrency. For the effective implementation of cryptocurrency, Ukraine lacks only the normative framework. Developing a regulatory framework in this area will help to bring cryptocurrency markets to stability. The introduction of international experience in the usage of cryptocurrency in Ukraine, the creation of own model of behaviour will be the first step towards building a transparent and understandable cryptocurrency market, which will lead to the development of the economy as a whole.
Cryptocurrencies are a novel and disruptive technology that has prompted a new approach to how currencies work in the modern economy. As such, online discussions related to cryptocurrencies often go beyond posts about the technology and underlying architecture of the various coins, to subjective speculations of price fluctuations and predictions. Furthermore, online discussions, potentially driven by foreign adversaries, criminals or hackers, can have a significant impact on our economy and national security if spread at scale.
Since the inception of Bitcoin in 2008, cryptocurrencies have played an increasing role in the world of e-commerce, but the recent turbulence in the cryptocurrency market in 2018 has raised some concerns about their stability and associated risks. For investors, it is crucial to uncover the dependence relationships between cryptocurrencies for a more resilient portfolio diversification. Moreover, the stochastic behavior in both tails is important, as long positions are sensitive to a decrease in prices (lower tail), while short positions are sensitive to an increase in prices (upper tail). In order to assess both risk types, we develop in this paper a flexible copula model which is able to distinctively capture asymptotic dependence or independence in its lower and upper tails simultaneously. Our proposed model is parsimonious and smoothly bridges (in each tail) both extremal dependence classes in the interior of the parameter space. Inference is performed using a full or censored likelihood approach, and we investigate by simulation the estimators' efficiency under three different censoring schemes which reduce the impact of non-extreme observations. We also develop a local likelihood approach to capture the temporal dynamics of extremal dependence among two leading cryptocurrencies. We here apply our model to historical closing prices of five leading cryotocurrencies, which share most of the cryptocurrency market capitalizations. The results show that our proposed copula model outperforms alternative copula models and that the lower tail dependence level between most pairs of leading cryptocurrencies -- and in particular Bitcoin and Ethereum -- has become stronger over time, smoothly transitioning from an asymptotic independence regime to an asymptotic dependence regime in recent years, whilst the upper tail has been relatively more stable overall at a weaker dependence level.
The Bitcoin protocol and its underlying cryptocurrency have started to shape the way we view digital currency, and opened up a large list of new and interesting challenges. Amongst them, we focus on the question of how is the price of digital currencies affected, which is a natural question especially when considering the price rollercoaster we witnessed for bitcoin in 2017-2018. We work under the hypothesis that price is affected by the web footprint of influential people, we refer to them as crypto-influencers.
Maribel Acosta, Tim Berners‐Lee, Stefan Dietze, Anastasia Dimou · 9 authors
Decentralised data solutions bring their own sets of capabilities, requirements and issues not necessarily present in centralised solutions. In order to compare the properties of different approaches or tools for management of decentralised data, it is important to have a common evaluation framework. We present a set of dimensions relevant to data management in decentralised contexts and use them to define principles extending the FAIR framework, initially developed for open research data. By characterising a range of different data solutions or approaches by how TRusted, Autonomous, Distributed and dEcentralised, in addition to how Findable, Accessible, Interoperable and Reusable, they are, we show that our FAIR TRADE framework is useful for describing and evaluating the management of decentralised data solutions, and aim to contribute to the development of best practice in a developing field.
Yu‐Jin Kwon, Jian Liu, Minjeong Kim, Dawn Song · 5 authors
Bitcoin uses blockchain technology and proof-of-work (PoW) mechanism where nodes spend computing resources and earn rewards in return for spending these resources. This incentive system has caused power to be significantly biased towards a few nodes, called mining pools. In fact, poor decentralization appears not only in PoW-based coins but also in coins adopting other mechanisms such as proof-of-stake (PoS) and delegated proof-of-stake (DPoS). In this paper, we target this centralization issue. To this end, we first define (m, \varepsilon, δ)-decentralization as a state that satisfies 1) there are at least m participants running a node and 2) the ratio between the total resource power of nodes run by the richest and δ-th percentile participants is less than or equal to 1+\varepsilon. To see if it is possible to achieve good decentralization, we introduce sufficient conditions for the incentive system of a blockchain to reach (m, \varepsilon, δ)-decentralization. When satisfying the conditions, a blockchain system can reach full decentralization with probability 1. However, to achieve this, the blockchain system should be able to assign a positive Sybil cost, where the Sybil cost is defined as the difference between the cost for one participant running multiple nodes and the total cost for multiple participants each running one node. On the other hand, we prove that when there is no Sybil cost, the probability of reaching (m, \varepsilon, δ)-decentralization is upper bounded by a value close to 0, considering a large rich-poor gap. To determine the conditions that each system cannot satisfy, we also analyze protocols of all PoW, PoS, and DPoS coins in the top 100 coins according to our conditions. Finally, we conduct data analysis of these coins to validate our theory.
Amin Kharraz, Zane Ma, Paul Murley, Charles Lever · 9 authors
In-browser cryptojacking is a form of resource abuse that leverages end-users' machines to mine cryptocurrency without obtaining the users' consent. In this paper, we design, implement, and evaluate Outguard, an automated cryptojacking detection system. We construct a large ground-truth dataset, extract several features using an instrumented web browser, and ultimately select seven distinctive features that are used to build an SVM classification model. Outguardachieves a 97.9% TPR and 1.1% FPR and is reasonably tolerant to adversarial evasions. We utilized Outguardin the wild by deploying it across the Alexa Top 1M websites and found 6,302 cryptojacking sites, of which 3,600 are new detections that were absent from the training data. These cryptojacking sites paint a broad picture of the cryptojacking ecosystem, with particular emphasis on the prevalence of cryptojacking websites and the shared infrastructure that provides clues to the operators behind the cryptojacking phenomenon.
Ethereum is an open-source, public, blockchain-based distributed computing platform and operating system featuring smart contract functionality. In this paper, we proposed an Ethereum based eletronic voting (e-voting) protocol, Ques-Chain, which can ensure the authentication can be done without hurting confidentiality and the anonymity can be protected without problems of scams at the same time. Furthermore, the authors considered the wider usages Ques-Chain can be applied on, pointing out that it is able to process all kinds of messages and can be used in all fields with similar needs.