With the public key being the parameter users are mostly addressed by on blockchain network, an intruder can connect transactional patterns to the public key and make a probable revelation of the identity of the user. Due to the diversity in approaches in achieving privacy, integrating the principle of transparency in any blockchain - edge computing platform will present some structural security challenges. Thus, an attempt should be made to achieve confidentiality whilst not eliminating a key principle of blockchain - transparency. Based on elliptic curve cryptosystem (ECC), we present a privacy-aware scheme that preserves the privacy details of the user in a blockchain-edge computing environment based on a combination of randomly generated public keys and digital signatures. The resilience and practicality of our scheme were tested on AVISPA and NS2 respectively. The results indicated our scheme was robust against attacks, efficient and low on computation resources of edge devices.
Open access
Blockchain Technology Applications and Security
Advanced Steganography and Watermarking Techniques
With the gradually opening of energy markets and popularization of Electric Vehicles (EVs), EVs can transmit, dispatch and recharge energy in different markets and domains dynamically. However, in Vehicular Energy Network, EVs may randomly enter and leave a market, it imposes a difficult problem in that how to schedule and distribute energy effectively. Additionally, the location of EV owners usually includes sensitive information such as home addresses, company names, hospital traces, and so on, which may be collected by attackers and may result in the privacy leakage about EV owners. In this article, we propose a decentralized blockchain-enabled energy trading scheme that can trade cross over various domains efficiently, which enables reliable transactions between EVs and energy nodes within short processing delay. It can also preserve the privacy of EV owners, by adopting the k-anonymity method in constructing a united request to hide the location information and creating a clocking area based on undirected graphs. Even though the server is maliciously attacked, the attacker cannot distinguish among EV owners, which breaks the linkage between real locations and identities to preserve EV owners' privacy. Finally, we conduct a comprehensive experimental evaluation to evaluate the trading performance and location privacy protection performance. The simulation results show that our proposed architecture outperforms over most state-of-the-art schemes in terms of processing delay and location privacy awareness.
With the considerable exploration of blockchain in various industrial fields, the storage architectures of mainstream consortium blockchains exhibit significant performance limitations, which can't meet the requirements of efficient data access with massive data storage in enterprise-level business scenarios. In this paper, we creatively divided the underlying data of the consortium blockchain into two categories: continuous data and state data and proposed a new storage architecture to store and operate these two types of data efficiently. For continuous data, we designed a specialized index-based storage engine. For state data, we proposed a multi-level cache mechanism with a secure and integrated data persistence policy. In addition, a pluggable Client/Server mode is employed to achieve flexible distributed extension. A series of experiments are conducted to show the effectiveness of our architecture. Compared with mainstream consortium blockchain storage architecture based on LevelDB, the average time-consuming decreases 81.85%/82.47% for reading/writing continuous data and 22.21%/48.99% for reading/writing state data. Compared with the storage architecture based on distributed database TiKV, the time-consuming decreases more significantly. This storage architecture has been integrated into the enterprise-level consortium blockchain platform Hyperchain, which has supported the efficient running of dozens of large-scale commercial blockchain projects with massive data.
Big data sharing in Cyber-Physical-Social Systems (CPSSs) relies on wireless transmission between numerous devices, causing a serious scarcity of radio spectrum resources. Although license-free spectrum access has great potential to alleviate the growing scarcity of spectrum resources, spectrum competition is more intense due to lower access requirements. A blockchain technology may solve this competition problem by introducing a dynamic cycle of “competition-verification-synchronization-competition”. In this paper, we propose a general framework for license-free spectrum resource management in CPSSs based on blockchain technologies and smart contracts. The management framework is mainly used for edge computing of non-real-time data. In particular, we divide spectrum of a local cell into multiple channels and each channel corresponds to a blockchain. Then, we propose a blockchain-KM protocol that may improve transaction processing speed without losing typical attributes of a general blockchain. For the proposed Blockchain-KM protocol, the entire private chain becomes a multi-ring blockchain and users rely on mining or leasing to access wireless spectrum. Different from the traditional mining process, the reward in our mining process is not only virtual currency but also a spectrum access license. Once a miner obtain a spectrum access license, it will exploit the license to transmit its messages over wireless links. Also, the miner may sell its license by an auction when it does not want to transmit messages. In the auction, we introduce a virtual currency, called as Xcoin, for spectrums or other trading (e.g., paid edge computing services).
The principles of contract law have shown continued resilience in light of constant technological developments, including the mainstream adoption of the Internet. The ability to absorb technological change may be attributable to the broad manner of their formulation. For example, the foundational proposition that ‘legal intention can be expressed in any manner’ has enabled the nearly seamless acceptance of online contracting. If intention can be manifested by a nod or a handshake, it can also take the form of a click or a swipe. Similarly, the requirement of consideration can be met not only by peppercorns or money, but also by one’s permission to share personal information in return for the provision of online content and services. While the Internet hardly creates academic excitement anymore, a number of internet- related technologies may pose a challenge to the principles of contract law and may, finally, test their flexibility. Purportedly, blockchain-based smart contracts, which are often defined as the encoding of legal terms in self-executing computer code, enable not only the automation of performance but also the delegation of enforcement to immutable code. The theory is that if both performance and enforcement are entrusted to impartial machines, breach becomes impossible. Smart contracts are also premised on the ability to translate contractual obligations into algorithms – a process aimed at the elimination of ambiguity and enhancement of legal certainty. Abstracting from technological minutiae, we must inquire whether, or to what extent, such ‘operations’ are desirable or legally permissible. The challenges of automation are further aggravated by advancements in artificial intelligence. The accompanying problems exceed those inherent in the possibility of inadvertent orders, unforeseen transactions or computer errors. We are forced to inquire whether such technological phenomena as algorithmic trading, machine learning or autonomous agents affect the existence of intention and, on a broader level, raise problems concerning the validity and enforceability of any resulting contract – if only due to the unprecedented transactional imbalances introduced by them. An additional set of difficulties concerns ubiquitous computing, loosely defined as the user-facing technologies involving the Internet-of-Things (‘IoT’). Smart objects and self-checkout terminals blur the division between online and offline environments and force a revision of our understanding of ‘online contracting.’ When the Internet spills over our computer screens and when we encounter requests for consent and contractual terms in contexts that have traditionally been non-commercial, it becomes difficult to rely on such basic principles as the objective theory of contract or on the presumption that in commercial contexts the parties intend to be legally bound. The point is not to question the continued applicability of such principles or presumptions but to illustrate the difficulty in their application. In sum, my chapter explores the legal implications of the said technologies and, while abstaining from unnecessary futurism, presents a realistic picture of their legal relevance. Particular attention is devoted to the overreaching question whether the principles of contract law, in their traditional formulation, are capable of accommodating (or withstanding ?) technological change. While it is difficult to predict technological trajectories and future legal developments, it is possible to extrapolate from existing trends and anticipate certain theoretical bottlenecks created by technological change.
Are cryptocurrencies indeed currencies? Anecdotal evidence on the volatility of cryptocurrency prices suggest that these “currencies” are not a good store of value, and similarly the time delays in validating and publishing crypto-based transactions suggest that they are not a good medium of exchange either. Due to the context it is defined in, it seems to not follow social conventions of fiat currencies. In this thesis, we undertake a systematic evaluation of how much do cryptocurrency prices behave like fiat currency prices, focusing on the predominant cryptocurrency — Bitcoin. We test the usefulness of various time series and structural models to predict future changes in Bitcoin prices and conclude that when predicting out of sample, its price is as unpredictable as fiat currency prices. Since cryptocurrencies generally have no central authority and hence receive no regulation, we explore its country-dependent characteristics, and find that the overall conclusions apply. We also examine if nominal interest rate differentials denominated in fiat currencies versus Bitcoin predict exchange rate movements, and find that in addition to the persistent violation in short-run, interest parity suggest that Bitcoin price has not been rising fast enough. We conclude that we have to refine the definition of monetary parameters on cryptocurrencies to better capture its properties, but as far as our examination indicates, the price of the predominant cryptocurrencies behaves similarly to most fiat currencies. In our point of view, Bitcoin is a currency.<br>
Blockchain is considered an emerging technology, having aroused the interest of researchers \nand industries on the world stage. After the success of this technology in the financial market \nwith virtual currencies (such as Bitcoin and Litecoin), blockchain starts to be used by different \ndomains, such as government and education, as it provides a reliable, scalable and immutable \ndistributed environment for the realization and storage of transactions on a network. Smart \ncontracts are one of the features of the Ethereum blockchain, which has the ability to run a \nprogramming model for applications distributed in untrusted environments. These contracts \nreside on the blockchain and enable process automation in several stages. Smart contracts have \nbecome one of the most sought-after technologies due to the high customization they add to \ntransactions, allowing to seek blockchain-based solutions to problems in industry and academia. \nHigher education is a system with several challenges that can be solved with the adoption of \nthis technology. Protecting data transactions involving student degrees is one of the challenges \nconsidered by educational institutions. Thus, this work presents an architecture proposal based \non blockchain technology to store and consult data from diplomas issued by higher education \ninstitutions. Through this architecture, a new approach for the validation of diploma data with \nthis emerging technology was evaluated. As a proof of concept, a prototype of the environment \nwas implemented using smart contracts based on the Ethereum platform. After implementation, \nan evaluation was carried out with specialists in the management of diplomas and an analysis \nof the performance of the transactions carried out in the prototype was carried out. In view of \nthe results obtained, the proposal proved to be adequate to the process of storing and consulting \ndiploma data.
We try to verify properties of the Bitcoin-S library, a Scala implementation of parts of the Bitcoin protocol. We use the Stainless verifier which supports programs in a fragment of Scala called Pure Scala. Since Bitcoin-S is not written in this fragment, we extract the relevant code from it and rewrite it until we arrive at code that we successfully verify. In that process we find and fix two bugs in Bitcoin-S.
In recent years, the Bitcoin investment market has become increasingly popular. We collected existing literature on Bitcoin and found that predictions about the role of Bitcoin in investment portfolios and the volatility of Bitcoin price as well as return have become advanced research topics. This study shows our current work on the prediction of Bitcoin price volatility and proposes an idea for predicting the price volatility. We have designed an experiment that compares different combinations of machine learning algorithms with GARCH-type models, intending to compare the effects of these models in the prediction of Bitcoin time series and finally implement an optimized algorithm.
Dieser Beitrag untersucht die Einwilligung im Kontext der Humanforschung und zeigt auf, welche Gesetzesänderungen notwendig sind, um die Grundlagen für ein elektronisches Einwilligungsverfahren zu schaffen. Anhand der Funktionen der einzelnen Merkmale der Schriftlichkeit wird ein aktuelles prototypisches Verfahren und die Möglichkeiten der Distributed-Ledger-Technologie geprüft.
Moving large amounts of data between networks for data analysis and computations presents several issues related to privacy and security. In collaboration with the TOTEM project [1], we propose a solution to these problems, by moving computations to the residence of the data. We introduce a novel approach for managing access to remote datasets and resources by blockchain technology through Hyperledger Fabric. Organizations with similar interests may join a consortium, which will form a private channel on the blockchain network, i.e., a separate ledger. Participating organizations will enroll their users, who thereafter must obtain a one-time-code using a smart contract in order to gain access to remote resources. We utilize Ansible for remotely deploying Hadoop clusters for computation, which will comprise several Docker containers. A user may run computations at several remote locations separately, and subsequently retrieve a combined result without having to share data between organizations. To ensure privacy between participating organizations we utilize chaincode and private data collections in Hyperledger Fabric. Finally, we demonstrate three ways of deploying the solution: locally, as a single cluster in the cloud using Azure, and across multiple clusters in the cloud using Azure. Our solution ensures data privacy by allowing data providing organizations to connect their own computational resources for data consumers to use. By running computations inside Docker containers on these resources, we ensure that these processes are isolated from the host system.
The massive scale, heterogeneity and distributed nature of Internet-of-Things (IoT) presents challenges in realizing a practical and effective security solution. Blockchain empowered platforms and technologies have been proposed to address aspects of this challenge. In order to realize a practical Blockchain deployment for IoT, there is a need for a testing and evaluation platform to evaluate performance and security of Blockchain applications and systems. In this paper, we present a Blockchain simulator that evaluates the consensus algorithms in a realistic and configurable network environment. Though, there are several Blockchain evaluation platforms, they are either wedded to a specific consensus protocol and do not allow evaluation in a configurable and realistic network environment. In our proposed simulator, we provide the ability to evaluate the impact of the consensus and network layer that will inform practitioners on the appropriate choice of consensus algorithms and the impact of network layer events in congested or contested scenarios in IoT. To accomplish this a generalized representation for consensus methods is proposed. The Blockchain simulator uses a discrete event simulation engine for fidelity and increased scalability. We evaluate the performance of the simulator by varying the number of peer nodes and number of messages required to find consensus.
Mobashar Mubarik, Raja Zuraidah binti Raja Mohd Rasi, Muhammad Faraz Mubarak
The study aims to identify the role of the blockchain-based supply chain in supply chain integration. The study also aims to investigate the role of various factors that possibly mediate the relationship between blockchain-based supply chain management and supply chain integration. The study adopted a twofold mixed-method approach—sequential explanatory— to attain the objectives. In the first phase, data were collected from Malaysian electrical and electronic firms, and by applying PLS-SEM, hypothesized relationships were examined. In the second phase, through a qualitative study, the results of the first phase are discussed with the industry experts to seek their expert opinion. In doing so, the semi-structured interview from seven experts, selected through purposive sampling, were conducted. The findings of both inquiries reveal that blockchain technology has significant potential to enhance the integration between numerous actors in multi-level supply chains while ensuring the transparency and traceability in the transactions. Moreover, the findings reveal that certain pre-requisites are missing at the moment in the Malaysian manufacturing sector, which are inevitable to be met, before implementing the block-chain based supply chain. Sophisticated infrastructure which could suffice the blockchain-based technologies implementation in supply chains and the absorptive capacity is prominent amongst them. Consequently, it is recommended that appropriate training should be given to employees in order to cater to the requirement of the technical skills needed to handle such advanced technology. Further, continuous infrastructural investments should be made to implement blockchain-based technology in the business ecosystem of Malaysia at the government level.
Today, the coronavirus infection COVID-2019 deals a devastating blow to the economies of most countries due to disruption of production chains, the bankruptcy of small and medium-sized businesses, increasing the number of unemployed, and more. Under these conditions, the coverage of digitalization of all sectors of the economy and basic spheres of life of citizens becomes especially important. The article is devoted to the analysis of the possibilities of the latest blockchain technologies, artificial intelligence, and the Internet of Things in view of their impact on the transformation of the business process management system. The study used methods of bibliographic analysis of scientific publications and analytical reports of international organizations related to the concept of “Industry 4.0” and diseases of coronavirus infection, analyzing from the audit point of view, how to reinforce the principles of transparency, responsibility, and participation. It has been proven that blockchain technology is able to service online payments without intermediaries, receipt, and transfer of digital assets, as well as political elections and voting. Artificial intelligence models can help map, manage, predict, and model complex processes, reducing uncertainty, and supporting professionals in decision-making. The Internet of Things allows you to transfer information, improve control and automation, and provide opportunities to optimize the company’s operating costs. The result of the study can be practically valuable for many stakeholders: auditors – conducting audits by artificial intelligence; public administration – developing measures to address the economic, social and political crisis triggered by the pandemic, by building trust between government and citizens through communication, and by ensuring transparency and accountability. Keywords: blockchain, artificial intelligence, Internet of Things, COVID-19, health care crisis, economic crisis, political crisis, control, public administration, financial management.
An increasing number of wind farms and mining operations located far off the coast will lead to the development of offshore substations. To avoid the large costs associated with platforms and floaters, such a substation can be placed on the seabed and controlled remotely. The conventional solution is to place the power components, e.g. switchgear placed inside thick-walled pressure-proof vessels to protect them from water and high pressure on the seabed. For current switching in medium voltage applications, there are mainly two options: vacuum circuit breakers or gas circuit breakers (filled at atmospheric or slightly elevated pressure). Whichever option is chosen, power cable feed-throughs or penetrators from the high-pressure water environment into the low pressure inside the vessel are required. These features add substantial technical complexity and costs, in particular at large sea depths. A novel concept is used in this thesis, where the interruption chamber of the circuit breaker can be gradually filled as the switchgear is lowered until finally reaching the same pressure as on the seabed. Reducing the differential pressure on the encapsulation will reduce the overall cost and complexity of such subsea substations. The gas pressures in this case may be in the range of up to tens of bars.\nIf the temperature and pressure of a gas exceed its critical point, it enters a supercritical state. In this state, the physical properties are between that of a gas and a liquid. The properties include high diffusivity, high heat conductivity, high heat capacity, high dielectric strength and an absence of vapour bubbles. These properties of the supercritical fluid are believed to be in favour of a successful current interruption medium. However, there is a distinct lack of knowledge on arc properties and the current interruption capability of extremely high-pressure gasses as well as on the supercritical region. In this thesis, nitrogen (N2) is chosen for its low critical point (33.5 bar, 126 K), good insulation strength and environment-friendly nature. As the critical temperature of N2 is lower than room temperature, the transition to supercritical state can be achieved by pressurizing N2 above 33.5 bar.\nThis thesis reports on the experimental investigation of the characteristics of N2 arc as a function of filling pressure as well as in the supercritical state. For the bulk of the study, filling pressures of 1, 20, 40 and 80 bar are investigated, the latter two being in the supercritical state. A fixed electrode arrangement is used where the arc is initiated by the melting of a copper ignition wire. The investigated arc current amplitude is in the range of 85 A to 450 A at a frequency of 190 Hz to 950 Hz. Based on the focus area of different phases of the arc, this thesis can primarily be divided into three major parts. First, the arc properties during the high-current phase, i.e. during current peak time, are investigated for free-burning and tube-constricted arcs. In the second phase, the investigation is focused near the current zero (CZ) where the thermal phase of the arc is studied. In the final phase, the post-arc dielectric recovery characteristics are studied. The effect of the forced gas flow is investigated in both the thermal and dielectric phase of the arc.\nBased on the experimental results, the arc voltage is found to increase with the filling pressure without any abrupt change during the transition from gas to the supercritical state. Increased current density due to the constriction of the arc at high filling pressure turned out to be the dominant factor for the high arc voltage. When the free-burning arc is physically constricted by means of burning inside a tube, an inverse relation between the arc voltage and the inner tube diameter is observed at 1 bar, as expected. At higher filling pressures, however, such a simple relationship does not exist. The reduced arc radius and the increased absorption of radiation at high filling pressures may limit the interaction between the arc and the tube.\nThe energy deposition in the arc increases while the arc radius decreases with increasing filling pressure. The arc gets constricted and as a result the temperature of the arc core increases. In the free-burning arc, in the absence of forced cooling, the arc core fails to dissipate the stored thermal energy quickly. As a result, without efficient cooling a high post-arc current is often observed at a high filling pressure compared to at 1 bar. The high energy deposition in the post-arc channel due to increased post-arc current causes an early re-ignition at high N2 pressure compared to at 1 bar. A forced gas flow, however, significantly enhances cooling at high filling pressures and improves the interruption performance.\nIn the free-burning arc arrangement, the post-arc dielectric strength of the gap increases rapidly with increasing filling pressure, only after a critical time delay following CZ. This critical time delay is probably linked to the temperature decay of the gap. Below the critical time delay, however, the dielectric strength of the gap is lower at a higher filling pressure in contrast to at 1 bar, similar to what is observed in the thermal re-ignitions of the freeburning arc. Forced gas flow significantly enhances the dielectric recovery of the arc channel at a high filling pressure, also in the thermal phase. The experiments indicate that although the thermal phase is the critical phase of the ultrahigh-pressure N2 arc interruption, the dielectric phase is inherently superior at a high filling pressure compared to atmospheric pressure. With the help of efficient cooling, the thermal phase can be improved, and hence the ultrahigh-pressure N2 reveals its potential to be used as a current interruption medium.
The purpose of this thesis is to study the predictability of cryptocurrency returns by investor attention, the interconnections of the cryptocurrency market, and what causes attention to cryptocurrencies. This is done by examining Bitcoin, Ethereum and Ripple which are the three biggest cryptocurrencies by market capitalization in January 2020. The dataset is constructed from weekly returns, weekly changes in investor attention measured by Google trend data and weekly changes in average weekly trading volume between years 2016 and 2019. The empirical analysis is conducted by performing OLS regressions, vector autoregressions and Granger causality tests. Additional robust tests are conducted by dividing the sample in pre-bubble and post-bubble samples adding all of the investor attention proxies to individual Cryptocurrency regressions. The results suggest that the market phase for a cryptocurrency affects the predictability of returns as the statistically significant positive relationship between investor attention disappears in the post-bubble sample for Bitcoin and Ethereum but endures for Ripple in both samples. This provides more evidence for the earlier findings that cryptocurrencies become more efficient as the market matures. The interconnections of the cryptocurrency market are shown to exist as the returns of Bitcoin drive investor attention to Ripple which is shown to be a significant predictor for all of the three cryptocurrencies in the whole sample. The spillover effect is shown to take time confirming earlier findings and unfolding the herding effect via investor attention in cryptocurrencies. Additionally, investor attention is shown to be caused by earlier returns for the cryptocurrency as well as the returns of Bitcoin. These results explain the interconnections of cryptocurrencies, the changing market dynamics in the cryptocurrency market, and the predictability of cryptocurrency returns by investor attention.
Afees A. Salisu, Ahamuefula E. Ogbonna, Tirimisiyu F. Oloko
This study examines the effect of a pandemic-induced uncertainty on cryptocurrencies (specifically, Bitcoin, Ethereum and Ripple). It employs a predictive model by Westerlund and Narayan (2012, 2015) to examine the predictability of a pandemic-induced uncertainty as a predictor, as well as the forecast performance of our predictive model for cryptocurrency returns. We examine the role of asymmetry in uncertainty and the sensitivity of our results to alternative measures of uncertainty due to pandemics, using the recently developed Global Fear Index (GFI) by Salisu and Akanni (2020). Our results indicate that cryptocurrencies could act as hedge against uncertainty due to pandemics, albeit with reduced hedging effectiveness in the COVID-19 period. Accounting for asymmetry is found to improve the predictability and forecast performance of the model, which indicates that failure to account for asymmetry in modeling the effect of a pandemic-induced uncertainty on cryptocurrency may lead to incorrect conclusion. The results seem to be sensitive to the choice of measure of pandemic-induced uncertainty.
A cryptocurrency is a decentralised digital currency that utilises blockchain technology to remove the role of a central authority. Monero is one of the cryptocurrencies that improves its anonymity by employing privacy-preserving cryptographic techniques, such as linkable ring signature. In this thesis, we explore three areas in Monero system that can cause anonymity problems. These areas are Monero transaction creation protocol, Monero protocol update, and Monero third-party services. We identify attack schemes to reduce honest users' transaction anonymity. We then investigate the impact of Monero protocol updates to transaction anonymity. Lastly, we study wallet service providers that can trace Monero transactions and mining pools that leak information.
In econophysics, statistical-physics techniques are used to model economical systems. In this thesis, we investigate the entropy and the Computational Information Density (CID) of the Bitcoin blockchain. The CID is defined as the compression ratio of some particular algorithm when applied to the raw data of the state of the system. It is related to entropy as both CID and entropy are measures of information.\nWe find a strong correspondence between the CID and entropy for the Bitcoin blockchain, where features are similar, but without one being a clear function of the other. This can be explained by intercorrelations between one agent and the next, which the entropy does not count. We also calculate some correlations to see if the CID and the entropy have some predictive power for the price, and we find a small correlation, but very small in comparison to the predictive power of the price itself.\nThese results the power of the CID-entropy correspondence and how the Bitcoin blockchain may be used as a useful large-scale toy model for econophysics. We anticipate that these results can be used for a further look into the CID-entropy relation, as the similarities are visible but there is no exact correspondence. Besides this, these results can form a basis for a further look into the predictive power of the CID or the entropy for the price.
Wenn das Vertrauen in das Bankensystem schwindet oder einfach nur der Wohlstand gesichert werden soll, sind Bitcoin und Gold diebesten Wertaufbewahrungsmöglichkeiten. Oder?