The problem of peer selection, which randomly selects a peer from a set, is commonplace in Proof-of-Stake (PoS) protocols. In PoS, peers are chosen randomly with probability proportional to the amount of stake that they possess. This paper presents an approach that relates PoS peer selection to Roulette-wheel selection, which is frequently used in genetic and evolutionary algorithms or complex network modelling. In particular, we introduce the use of stochastic acceptance algorithm [6] for fast peer selection. The roulette-wheel selection algorithm [6] achieves O(1) complexity based on stochastic acceptance, whereas searching based algorithms may take O(N ) or O(logN ) complexity in a network of N peers.
This paper provides a systematic survey on return and volatility spillovers of cryptocurrencies based on the empirical results of relevant academic literature. Evidence reveals that Bitcoin is the most influential among digital coins mainly as a transmitter toward digital currencies but also as a receiver of spillovers from virtual currencies and alternative assets. Ethereum, Litecoin, and Ripple present the most significant interlinkages with Bitcoin. Return spillovers are more pronounced but volatility spillovers often present a bi-directional character. Volatility shock transmission is detected among Bitcoin and national currencies, while economic policy uncertainty is not influential. This survey provides useful guidance in the hotly-debated issue of reform and decentralization of financial systems.
Proof of Work (PoW) is a Sybil-deterrence security mechanism. It introduces an external cost to a system by requiring computational effort to perform actions. However, since its inception, a central challenge was to tune this cost. Initial designs for deterring spam email and DoS attacks applied overhead equally to honest participants and attackers. Requiring too little effort did not deter attacks, whereas too much encumbered honest participation. This might be the reason it was never widely adopted. Nakamoto overcame this trade-off in Bitcoin by distinguishing desired from malicious behavior and introducing internal rewards for the former. This solution gained popularity in securing cryptocurrencies and using the virtual internally-minted tokens for rewards. However, in existing blockchain protocols the internal rewards fund (almost) the same value of external expenses. Thus, as the token value soars, so does the PoW expenditure. Bitcoin PoW, for example, already expends as much electricity as Colombia or Switzerland. This amount of resource-guzzling is unsustainable and hinders even wider adoption of these systems. In this work we present Hybrid Expenditure Blockchain (HEB), a novel PoW mechanism. HEB is a generalization of Nakamoto's protocol that enables tuning the external expenditure by introducing a complementary internal-expenditure mechanism. Thus, for the first time, HEB decouples external expenditure from the reward value. We show a practical parameter choice by which HEB requires significantly less external consumption compare to Nakamoto's protocol, its resilience against rational attackers is similar, and it retains the decentralized and permissionless nature of the system. Taking the Bitcoin ecosystem as an example, HEB cuts the electricity consumption by half.
The study of Proof of Work (PoW) has culminated with the introduction of cryptocurrency blockchains like Bitcoin. These protocols require their operators, called miners, to expend computational resources and they reward them with minted cryptocurrency tokens. The system is secure from attackers who cannot expend resources at a rate equivalent to that of all benign miners. But the resource requirement is arbitrary - the product of the number of minted tokens and their real value. We present Hybrid Expenditure Blockchain (HEB), a novel cryptocurrency PoW protocol that allows its designer to tune external expenditure. To the best of our knowledge, this is the first tunable PoW protocol. Despite the reduced resource expenditure, it maintains the security guarantees of pure PoW protocols against rational attacks. HEB has practical implications, as global power expenditure on PoW blockchains exceeds that of a medium-sized country. Applying HEB in operational PoW systems can significantly reduce their ecological footprint.
Modern Blockchains support the execution of user programs, called smart contracts. As a trusted computing platform, smart contracts bring decentralization, computation integrity, open access and information transparency to average users on the Internet. However, running smart-contract programs leads to high costs, known as Gas. Such costs prevent the use of smart contracts in data-intensive application scenarios, such as high-frequency trading and transparency logging. This paper addresses the Gas-based cost effectiveness in the most consuming layer of a smart contract, namely data storage. We present GRuB, a dynamic data-replication framework that monitors the smart-contract workload and makes online replication decisions. A new online algorithm is proposed that provides constant-bounded 'competitiveness' in Gas. To further save Gas, the workload monitor and decision maker are run off the Blockchain and with security against the forging of workload trace being monitored. A GRuB prototype is built, including a smart-contract component on Ethereum and an off-chain middleware on top of Google LevelDB. The cost evaluation under the YCSB workloads shows that GRuB can converge quickly to changing workloads and save Gas significantly compared with static replication schemes. Two case studies are conducted for data-intensive applications, including high-frequency trading and transparency logging, in which running GRuB leads to affordable Gas.
Several initiatives have made available open educational resources, offered through educational platforms, aiming to achieve a broader audience, thus having the opportunity of democratizing knowledge. However, accessibility aspects in these resources still have many gaps. One is how to help teachers to prepare curricular contents available to all students, regardless of their limitations and disabilities. In this sense, this paper presents a digital ecosystem architecture, called SELI, that is being developed by a group of eleven European and Latin American countries. This ecosystem aims to provide an accessible learning environment and its contents, besides proper authoring tools based on recent technologies such as Blockchain, microsites, and universal accessibility guidelines.
With the development of science and technology, human beings cannot live without electricity. The introduction of smart grid systems brings new ideas to break the shackle of existing electricity systems. This paper proposes a mechanism with data monitoring and sharing capabilities based on the consortium blockchain, realizing comprehensive monitoring of smart devices, and promoting the effective sharing of electrical data in smart grids. When a smart device is out of order, the smart contract connected to it will be triggered, and the users can check the running status through the smart phone. This approach allows nodes in the consortium blockchain to request transactions, using the prepaid payment smart contract with time-lock script to protect the consumer right of request nodes. In addition, we use a (t, n) -threshold secret sharing scheme to realize multiparty sharing of electrical data. Paillier encryption arithmetic is used to guarantee the confidentiality of messages in node transaction.
<em>Regional Original Revenue (PAD) has a very large contribution to the Regio-nal Budgeting (APBD) to finance the administration and service processes of govern-ment affairs and regional development. The present research aims to determine how to improve PAD and build strategy of action plan for increasing it in Gunungkidul Regency. This study used descriptive qualitative method. Informants were taken by purposive sampling. Data collecting techniques are observations, interview with Local Agency Organizations (OPD) which are responsible for PAD generation, and docu-mentations or secondary data, i.e. APBD, PAD, and other relevant data. The results of the study showed that the development of Gunungkidul PAD experienced a significant development as big as 25,97%. The PAD contribution to regional income or fiscal decentralization rate is 11,73%. The strategy to increase the PAD is built by a formulating action plan for accelerating it. Based on this results, it is suggested that the program to increase competency and commitment of regional tax-retribution managers for each revenue management of local agency, provide a program to increase the PAD and implementation of the action plan to increase it, use information and communi-cation technology for the management of each PAD lines, and optimally stakeholders cooperation building.</em>
Summary Smart cities aim to provide smart governance with the emphasis on gaining high transparency and trust in public services and enabling citizen participation in decision making processes. This means on the one hand data generated from urban transactions need to be open and trustworthy. On the other hand, security and privacy of public data needs to be handled at different administrative and geographical levels. In this paper, we investigate the pivotal role of blockchain in providing privacy, self‐verification, authentication, and authorization of participatory transactions in open governance. We also investigate up to what extent edge computing can contribute toward management of permissioned sharing at specific administrative levels and enhance privacy and provide an economic approach for resource utilization in a distributed environment. We introduce a novel architecture that is based on distributed hybrid ledger and edge computing model. The architecture provides refined and secure management of data generated and processed in different geographical and administrative units of a city. We implemented a proof of concept of the architecture and applied it on a carefully designed use case, ie, citizen participation in administrative decisions through consensus. This use case highlights the need to keep and process citizen participation data at local level by deploying district chaincodes and only share consensus results through permissioned chaincodes. The results reveal that proposed architecture is scalable and provide secure and privacy protected environment for citizen participatory applications. Our performance test results are promising and show that under control conditions, the average registration time for a citizen transaction is about 42 ms, whilst the validation and result compilation of 100 concurrent citizens' transactions took about 2.4 seconds.
Feeding external data to a blockchain, a.k.a. data feed, is an essential task to enable blockchain interoperability and support emerging cross-domain applications, notably stablecoins. Given the data-intensive feeds in real life (e.g., high-frequency price updates) and the high cost in using blockchain, namely Gas, it is imperative to reduce the Gas cost of data feeds. Motivated by the constant-changing workloads in finance and other applications, this work focuses on designing a dynamic, workload-aware approach for cost effectiveness in Gas. This design space is understudied in the existing blockchain research which has so far focused on static data placement. This work presents GRuB, a cost-effective data feed that dynamically replicates data between the blockchain and an off-chain cloud storage. GRuB's data replication is workload-adaptive by monitoring the current workload and making online decisions w.r.t. data replication. A series of online algorithms are proposed that achieve the bounded worst-case cost in blockchain's Gas. GRuB runs the decision-making components on the untrusted cloud off-chain for lower Gas costs, and employs a security protocol to authenticate the data transferred between the blockchain and cloud. The overall GRuB system can autonomously achieve low Gas costs with changing workloads. We built a GRuB prototype functional with Ethereum and Google LevelDB, and supported real applications in stablecoins. Under real workloads collected from the Ethereum contract-call history and mixed workloads of YCSB, we systematically evaluate GRuB's cost which shows a saving of Gas by 10% ~ 74%, with comparison to the baselines of static data-placement.
Blockchain  and Cryptocurrency has gotten wider considerations as of late. The decentralized digital Cryptocurrency  and its underlying “Blockchain †technology has created much excitement in the technology community. The financial technology sector sees high potential value in Cryptocurrency Blockchain  protocols, or distributed-ledger technology. The key advantage of this technology lies in the fact that it enables the establishment of secured, trusted, and decentralized autonomous ecosystems for various scenarios, especially for better usage of the legacy devices, infrastructure, and resources. In this paper, we presented a systematic investigation of Blockchain  and Cryptocurrencies with explained simply in a way that Cryptocurrency is a form of digital currency that is being used to make transactions using a ledger known as Blockchain  which is a decentralized system of banking in which there is no centralized authority and all the control lies on an algorithm and its controlling users. Blockchain , a financial tool that can potentially play an important role in the sustainable development of the global economy. The new technology is expected to bring massive benefits to consumers, to current banking system and to the whole society in general.Â
Mahdi Fooladgar, Mohammad Hossein Manshaei, Murtuza Jadliwala, Mohammad Ashiqur Rahman
Algorand is a recent, open-source public or permissionless blockchain system that employs a novel proof-of-stake byzantine consensus protocol to efficiently scale the distributed transaction agreement problem to billions of users. In addition to being more democratic and energy-efficient, compared to popular protocols such as Bitcoin, Algorand also touts a much high transaction throughput. This paper is the first attempt in the literature to study and address this problem. By carefully modeling the participation costs and rewards received within a strategic interaction scenario, we first empirically show that even a small number of nodes defecting to participate in the protocol tasks due to insufficiency of the available incentives can result in the Algorand network failing to compute and add new blocks of transactions. We further show that this effect can be formalized by means of a mathematical model of interaction in Algorand given its participation costs and the current (or planned) reward distribution/sharing approach envisioned by the Algorand Foundation. Specifically, on analyzing this game model we observed that mutual cooperation under the currently proposed reward sharing approach is not a Nash equilibrium. This is a significant result which could threaten the success of an otherwise robust distributed consensus mechanism. We propose a novel reward sharing approach for Algorand and formally show that it is incentive-compatible, i.e., it can guarantee cooperation within a group of selfish Algorand users. Extensive numerical and Algorand simulation results further confirm our analytical findings. Moreover, these results show that for a given distribution of stakes in the network, our reward sharing approach can guarantee cooperation with a significantly smaller reward per round.
Muhammad Baqer Mollah, Jun Zhao, Dusit Niyato, Kwok‐Yan Lam · 8 authors
Due to the unique features and characteristics of blockchain technology, its applications have expanded across various sectors, including finance, banking, supply chains, and smart grids (SGs). Blockchain ensures security and trust in transactions without requiring a third party, making it particularly valuable in decentralized systems. This paper explores the integration of blockchain technology into SG systems. It begins with a comprehensive review of conventional and smart power grids, identifying the key challenges modern SGs face, particularly issues related to trust and fraud. An in-depth analysis of blockchain technology follows, highlighting its potential, advantages, and defining characteristics. The study then examines several blockchain-based SG applications and provides a comparative analysis of prior research. The findings of this review illuminate the critical role of blockchain in enhancing SG performance by addressing trust and fraud prevention challenges. Furthermore, this research has significant implications for the energy sector, as it underscores the potential of blockchain to revolutionize SGs through increased security, transparency, and efficiency. By providing a foundation for future studies, this paper aims to guide the development of unified blockchain frameworks that address scalability, privacy, and energy management, paving the way for a more secure and efficient decentralized energy system
The present work was carried out with the objective of knowing the behavior and evolution of Bitcoin, since its launch in the year 2009 until the first half of 2.018. The Bitcoin (BTC) is the first cryptocurrency launched on the market as a new means of payment option. The qualitative research initially included a literature review about the origin of its creation, growth, evolution and degree of acceptance within the market of new financial assets. It continued with the documentary review of its main characteristics, its legal and financial evolution, supported by secondary sources, especially in the reports of journals specialized in the subject and of investment and payment platforms. Then we proceeded to the explanatory modality where the advances of the currency were identified as the first decentralized cryptographic financial network in the world, as well as the specific experiences of its growth evolution that gave rise to the creation of the Bitcoin Foundation, strengthening the link between the currency and its acceptance as an innovative financial asset. The Bitcoin offers a new payment mechanism that has had a sustained growth and is generating a new financial relationship, where the low participation of intermediaries allows to obtain lower prices in transactions.
Wendy Charles, Natalie Marler, Lauren Long, Sean T. Manion
As clinical research moves toward real-world data capture with increased data sharing, there is a growing need for patient-centered technologies that ensure data authenticity and promote researcher and patient access. Blockchain is one of an emerging set of distributed ledger technologies with the potential to offer both research data transparency and trust, while offering robust security measures. As blockchain-based systems are being developed for clinical research applications, these systems may be required to follow state and federal research regulations, such as ethical protections for human participants and data privacy. Blockchain developers and research organizations alike are struggling to identify and interpret these regulatory requirements. Further, regulatory agencies and policymakers have not yet provided blockchain stakeholders with clear guidelines to achieve compliance. This article provides an introduction to the clinical research and health information privacy regulations in the United States as well as data design standards and electronic signature laws. We also offer recommendations for blockchain developers, researchers, and research organizations for achieving compliant blockchain solutions in clinical research.
Tejasvi Alladi, Vinay Chamola, Joel J. P. C. Rodrigues, S. A. Kozlov
With the integration of Wireless Sensor Networks and the Internet of Things, the smart grid is being projected as a solution for the challenges regarding electricity supply in the future. However, security and privacy issues in the consumption and trading of electricity data pose serious challenges in the adoption of the smart grid. To address these challenges, blockchain technology is being researched for applicability in the smart grid. In this paper, important application areas of blockchain in the smart grid are discussed. One use case of each area is discussed in detail, suggesting a suitable blockchain architecture, a sample block structure and the potential blockchain technicalities employed in it. The blockchain can be used for peer-to-peer energy trading, where a credit-based payment scheme can enhance the energy trading process. Efficient data aggregation schemes based on the blockchain technology can be used to overcome the challenges related to privacy and security in the grid. Energy distribution systems can also use blockchain to remotely control energy flow to a particular area by monitoring the usage statistics of that area. Further, blockchain-based frameworks can also help in the diagnosis and maintenance of smart grid equipment. We also discuss several commercial implementations of blockchain in the smart grid. Finally, various challenges to be addressed for integrating these two technologies are discussed.
The main goals of Higher Education Institutions (HEIs) are to develop the intellectual abilities of students as well asprepare them for entering the labor market. The connection between HEIs and the labor market is why the effectivenessand quality
Open access
Online Learning and Analytics
Intelligent Tutoring Systems and Adaptive Learning
Bitcoin is an innovative technological network, a new, non-governmental currency, and a worldwide group of users. In other words, Bitcoin is a complex sociotechnical system with a complex set of risks and challenges for anyone using it. We investigated how everyday users of Bitcoin develop trust in Bitcoin on one of the largest online communities devoted to Bitcoin: the Reddit.com r/bitcoin forum. Using qualitative content analysis, we examined how trust in Bitcoin develops based on contributions to this community. On r/bitcoin, trust in Bitcoin is driven by a pervasive ideology we call the "True Bitcoiner" ideology. This ideological viewpoint in centered on the interpretation of Bitcoin as functionally "trustless" and risk-free. Despite widespread evidence of emerging individual and system-level risks with using Bitcoin, participants continue to maintain this ideological perspective. This ideology consists of three primary beliefs: viewing Bitcoin's technology as more trustworthy than its people; rejecting 'corrupt' social hierarchies related to money; and the importance of accumulating or 'HODLing' quantities of Bitcoin as a strategy to create an ideal future. We conclude that this "True Bitcoiner" ideology is maintained despite contradictory evidence in the world because it allows participants to more easily interpret Bitcoin and make decisions by reducing perceived risk and uncertainty in the system. The role of this ideology on r/bitcoin demonstrates an expanded conceptualization of how trust is created and socially-mediated in socio-technical contexts.
Chris Elsden, Kate Symons, Raluca Bunduchi, Chris Speed · 5 authors
Recent work within HCI and CSCW has become attentive to the politics of data and metrics in order to highlight the implications of what counts and how. In this paper, we relate these discussions to the longstanding distinctions made between value and values. We introduce literature on 'Valuation Studies' and argue for understanding the politics of data through valuation - an ongoing social practice that transforms socially embedded values into different forms of more abstract value. This theoretical work is developed through an ethnographic study of contemporary UK charity shops, as a site focused on the labour of valuation, but embedded in both local and global values. Through this study, we consider implications for the intervention and design of 'data-driven innovation', with a particular focus on distributed ledger technologies. We argue that these technologies inevitably engage in valuation, and require careful attention to the ongoing processes by which value is translated and performed by different stakeholders.
Open access
Information Systems Theories and Implementation
FinTech, Crowdfunding, Digital Finance
Innovative Approaches in Technology and Social Development
The aim of this work is to analyze the major existing cryptocurrency consensus algorithms considering a number ofattributes that may play a significant role in the long-term sustainability of a cryptocurrency ecosystem and to comparativelyevaluate
Shantanu Pal, Tahiry Rabehaja, Ambrose Hill, Michael Hitchens · 5 authors
With the advancement of the Internet of Things (IoT) in recent years, there is a bigger potential to use online services than ever before. The use of the IoT brings numerous opportunities for both service providers and end users, however, it faces critical questions of security and privacy. Toward this, access control is one of the significant security challenges for the IoT, in particular, considering the characteristics of such IoT systems. To develop a secure access control architecture for the IoT, the propagation of access right delegation is a major issue. Many proposals present access control issues for the IoT but given the specific context of access right delegation, it is still in its infancy. This article presents an approach to address such a delegation issue for the IoT using the blockchain technology. We propose a delegation model that employv the critical issues, e.g., the use of nonunique identities, asynchronous and flexible delegation nature of communication for the IoT without the need of a centralized system. The goal of our primitive is to use attributes for validating the identity of an entity instead of relying on a concrete unique identity of an entity. To provide privacy for the attributes, we propose a dual blockchain architecture that moves the attribute storage and access of the public blockchain and onto a secure private blockchain. To demonstrate the feasibility of our proposed approach, we evaluate the system performances using the Ethereum blockchain network.
ABSTRACT: Proof-of-vote is a third generation of the Nakamoto consensus. With proof-of-vote, validators compete for people-votes, using proof-of-suffrage given by proof-of-person, and authorize transactions based on authority delegated by the consensus mechanism, just like proof-of-work or proof-of-stake. This logical conclusion of the Nakamoto consensus allows a “nation” of people to secure their own ledger, the equivalent of representative democracy for distributed ledger technology.
This Essay explores the barriers to deploying smart contracts in the consumer finance space: the humans themselves, existing consumer protection laws, and the other businesses which have financial contracts with consumers but that cannot deploy smart contracts. These three barriers render perfectly automated enforcement all but impossible. Nevertheless, there may be room for modifiable smart contracts in the consumer finance space – although these contracts may be only marginally more efficient than traditional contracts.
Sociotechnical imaginaries are futures that people envision might be possible and desirable. They have a real impact on how systems are designed and what values they have embedded in their design. This article examines imaginaries about autonomous systems, decentralized systems, and decentralized autonomous systems. Through a discussion of the literature on autonomous and decentralized systems and how these imaginaries play out in the blockchain community based on my qualitative research, I demonstrate how decentralized autonomous systems are related to imaginaries about the organization of and the future of work. I identify three framings of imaginaries about autonomous systems: (1) autonomous technology as physical objects, (2) as mathematical rules, and (3) as artificial mangers. I also identify two sometimes conflicting framings of imaginaries about distributed and decentralized technology: these technologies as a new form of production and as freedom from control. These imaginaries intersect in decentralized autonomous systems, and I examine what they can tell us about the design and governance of such technologies. Lastly, I suggest ways of using the concept of imaginaries in participatory design.