Abstract—As data is having an increasingly relevant role<br> in dierent business fields, ensuring integrity has become<br> fundamental. Modern databases rely on transaction history<br> written on redo logs to allow for data restore. However, if<br> redo logs are (maliciously) forged, data can actually be lost or<br> altered. Due its strong data integrity guarantees, blockchain<br> technology can be employed to ensure log integrity, but its<br> current performance limitations hinder actual exploitations.<br> In previous work, we proposed a layered blockchain-based<br> architecture for distributed (federated) database redo logs: a<br> fast first layer blockchain, anchored to a secure second layer<br> blockchain, based on proof-of-work to achieve strong integrity.<br> Here, we present an implementation and an experimental<br> evaluation of a prototype of that architecture, which employs a<br> total consensus algorithm on the first layer blockchain. Finally,<br> to improve availability and scalability, we refine our solution<br> by investigating, respectively, a Byzantine Fault Tolerant consensus<br> and a Distributed Hash Table solution to shard the first<br> layer blockchain ledger among available nodes.
Abstract Blockchain technologies are reconfiguring the global economy, though often in contradictory ways. Blockchain technologies are disrupting key economic and financial sectors. Some blockchain applications allow for democratization of finance, services, agriculture, and governance, yet they may also deepen inequality and weaken democracy. We need new understandings of the countervailing tendencies of blockchain technologies and the contingencies that shape their deployment.
Abstract Blockchain technology is considered, in some quarters, to have outgrown its primary association with the Bitcoin payments ecosystem. This belief has fostered numerous predictions of blockchain futures, in which the Bitcoin ecosystem is largely absent. It is nevertheless wholly possible to imagine a future for blockchain in which Bitcoin plays a presiding role. In drawing attention to subtexts of this kind, expectations of the future can prove highly persuasive within the context of technology selection and adoption processes of the present, lending an invisible hand to the design of business models, while also guiding strategic choices and the purchasing decisions made by managers.
Bloekehain - software technology used for peer-to-peer transaction platforms - is being increasingly applied to alternative opportunities for a variety of industries and use cases such as also in the energy sector. As of now all energy related to blockchain applications are still in a concept stage. This paper aims to present the preliminary ideas of a research project that we have launched in collaboration with a small Fintech company: the Crypto-Trading project. From a research perspective we have explored how a blockchain-based system integrating smart contract functionality can be used to share energy in order to promote smart grids for the management of electricity in the Sardinia Region. From a technical perspective the project will implement a modular blockchain-based software platform for extending the features of cryptocurrency exchanges to the renewable Energy Market, including a robo-advisor which will suggest prosumers the best selling strategy. Blockchain technology shows a lot of promise. In our opinion this might boost the growth of renewable energy production and consequently also have a positive effect on the regional economy.
Abstract Cryptocurrencies and blockchain technology are playing an increasingly important role for organizations that seek to build social and solidarity‐based finance. Blockchain technology has emerged as a potential disruptor for the financial industry. However, cryptocurrencies and blockchain technology may help develop organizations that seek to build social and solidarity‐based finance.
This document describes the Schnorr non-interactive zero-knowledge
(NIZK) proof, a non-interactive variant of the three-pass Schnorr
identification scheme. The Schnorr NIZK proof allows one to prove the
knowledge of a discrete logarithm without leaking any information
about its value. It can serve as a useful building block for many
cryptographic protocols to ensure that participants follow the
protocol specification honestly. This document specifies the Schnorr
NIZK proof in both the finite field and the elliptic curve settings.
Alexei Zamyatin, Katinka Wolter, Sam M. Werner, Peter G. Harrison · 6 authors
Cryptocurrency mining can be said to be the modern alchemy, involving as it does the transmutation of electricity into digital gold. The goal of mining is to guess the solution to a cryptographic puzzle, the difficulty of which is determined by the network, and thence to win the block reward and transaction fees. Because the return on solo mining has a very high variance, miners band together to create so-called mining pools. These aggregate the power of several individual miners, and, by distributing the accumulated rewards according to some scheme, ensure a more predictable return for participants.In this paper we formulate a model of the dynamics of a queue-based reward distribution scheme in a popular Ethereum mining pool and develop a corresponding simulation. We show that the underlying mechanism disadvantages miners with above-average hash rates. We then consider two-miner scenarios and show how large miners may perform attacks to increase their profits at the expense of other participants of the mining pool. The outcomes of our analysis show the queue-based reward scheme is vulnerable to manipulation in its current implementation.
Abstract Blockchain has the potential to become a significant source of disruptive innovations in business and management. There is a scarcity of knowledge and understanding of blockchain techniques that hinders its academic research and practical application. Business managers need to understand the potential impact and threat of blockchain applications in order to gain and maintain competitive advantage. Blockchain applications appear to offer considerable performance improvement and commercialization opportunities.
Ingo Weber, Vincent Gramoli, Alex Ponomarev, Mark Staples · 7 authors
Blockchain has recently gained momentum. Startups, enterprises, banks, and government agencies around the world are exploring the use of blockchain for broad applications including public registries, supply chains, health records, and voting. Dependability properties, like availability, are critical for many of these applications, but the guarantees offered by the blockchain technology remain unclear, especially from an application perspective. In this paper, we identify the availability limitations of two mainstream blockchains, Ethereum and Bitcoin. We demonstrate that while read availability of blockchains is typically high, write availability - for transaction management - is actually low. For Ethereum, we collected 6 million transactions over a period of 97 days. First, we measured the time for transactions to commit as required by the applications. Second, we observed that some transactions never commit, due to the inherent blockchain design. Third and perhaps even more dramatically, we identify the consequences of the lack of built-in options for explicit abort or retry that can maintain the application in an uncertain state, where transactions remain pending (neither aborted nor committed) for an unknown duration. Finally we propose techniques to mitigate the availability limitations of existing blockchains, and experimentally test the efficacy of these techniques.
Blockchain technology is an innovative framework that has the potential to transform transactions and revolutionise how we interact and do business with one another. The technology behind cryptocurrencies such as bitcoin, blockchain enables a record of transactions in a secure, protected ledger with a distributed, networked database structure, which is secured by hashing power. This allows transactions without any intermediary which are permanent, unalterable, anonymous but transparent and ‘trustless’ – occurring without the possibility of interference. Online gambling is the most rapidly growing mode of gambling; however, players are subject to regulatory restrictions, fraud and cheating by other players and disreputable operators, and reliant on third-parties to ensure that games and monetary transactions are fair. These systems, checks, and balances increase the cost of online gambling for consumers and operators and reduce options. Here, we show how blockchain technology and cryptocurrencies have the potential to transform the gambling industry for players, operators, and regulators. We have reviewed the relevant literature to provide an overview of the potential impacts of this new technology as it is rapidly developing. Gambling sites can accept cryptocurrency, allowing players to operate outside of regulatory jurisdictions as cryptocurrencies are not reliant on regulated payment providers. Cryptocurrency also allow funds to be directly transferred to and from operators, removing the necessity of creating an account and verifying identity. Games run on blockchain systems are provably fair, ensuring outcomes are determined as intended and without interference. Outcomes and transactions are verified, ensuring payments are directed to players or operators as appropriate and all records are transparent ensuring fairness. For players and operators this creates many options for online gambling; for regulators, it may enhance the ability to oversee online operators, or remove the need for regulation altogether. Blockchain technology is not yet at a point where it may be readily adopted and used widely. However, the transformative potential of this technology makes it essential that stakeholders start considering the ways in which the gambling field may be altered and what appropriate responses are required.
Dimitris Chatzopoulos, Mahdieh Ahmadi, Sokol Kosta, Pan Hui
During the last years, researche'rs have proposed solutions to help smartphones improve execution time and reduce energy consumption by offloading heavy tasks to remote entities. Lately, inspired by the promising results of message forwarding in opportunistic networks, many researchers have proposed strategies for task offloading towards nearby mobile devices, giving birth to the Device-to-Device offloading paradigm. None of these strategies, though, offers any mechanism that considers selfish users and, most importantly, that motivates and defrays the participating devices who spend their resources. In this paper, we address these problems and propose the design of a framework that integrates an incentive scheme and a reputation mechanism. Our proposal follows the principles of the Hidden Market Design approach, which allows users to specify the amount of resources they are willing to sacrifice when participating in the offloading system. The underlying algorithm, that users are not aware of, is based on a truthful auction strategy and a peer-to-peer reputation exchange scheme. Extensive simulations on real traces depict how our designed mechanism achieves higher offloading rate and produces less traffic compared to three benchmark algorithms. Finally, we show how collaborating devices get rewarded for their contribution, while selfish ones get sidelined by others.
After more than eight years since the launch of Bitcoin, the decentralized transaction ledger functionality implemented through the blockchain technology is being used not only for cryptocurrencies, but to register, confirm and transfer any kind of contract and property. In this work, we analyze the most relevant functionalities and known issues of this technology, with the intent of pointing out the possible behaviours that are not as efficient and reliable as they should be when thinking with a broader outlook.
Open access
Blockchain Technology Applications and Security
Cryptography and Data Security
Advanced Steganography and Watermarking Techniques
This paper presents a simple game theoretic framework, assuming complete information, to model Bitcoin mining activity. It does so by formalizing the activity as an all-pay contest: a competition where participants contend with each other to win a prize by investing in computational power, and victory is probabilistic. With at least two active miners, the unique pure strategy Nash equilibrium of the game suggests the following interesting insights on the motivation for being a miner: while the optimal amount of energy consumption depends also on the reward for solving the puzzle, as long as the reward is positive the decision to be an active miner depends only on the mining costs. Moreover, the intrinsic structure of the mining activity seems to prevent the formation of a monopoly, because in an equilibrium with two miners, both of them will have positive expected profits for any level of the opponent’s costs. A monopoly could only form if the rate of return on investment were higher outside bitcoin.
Distributed ledger technology (DLT) is emerging as a potential disruptive force in the financial services industry and has garnered significant interest from various stakeholders. The technology offers the potential of significant efficiency gains and risk reduction, but also brings with it a new set of risks such as those related to security and privacy. Some argue that it could change the status quo of how securities are issued, traded and cleared, and redefine the roles of various market players. This paper provides an overview of distributed ledger technology and explains key features such as public versus private networks, the use of digital assets, and the general process for conducting and verifying transactions and recording them on a DLT network. It then highlights some key applications being explored in the securities industry including those in the equity, debt and derivatives markets, and in the utilities space. Further, the paper explores the potential impact of the technology in key areas of market efficiencies, transparency, role of intermediaries and operations, and highlights related benefits and risks. Many of the securities laws that the Financial Industry Regulatory Authority (FINRA) is charged with overseeing are potentially implicated by various DLT applications.
Roger Maull, Phil Godsiff, Catherine Mulligan, Alan Brown · 5 authors
Abstract Distributed ledger technologies (DLTs) are rewriting conventional notions of business transacting, creating fresh opportunities for value creation and capture. Using qualitative interview data as a primary resource, the proposed five‐point model synthesizes these possibilities, demonstrating how they may lead to “disruptive innovation.” A further conceptual model is subsequently provided with a view to assisting future problem solving in the area.
Blockchain may help solve several complex problems related to securing the integrity and trustworthiness of rapid, distributed, complex energy transactions and data exchanges. In a move towards grid resilience, blockchain commoditizes trust and enables automated smart contracts to support auditable multiparty transactions based on predefined rules between distributed energy providers and customers. Blockchain based smart contracts also help remove the need to interact with third-parties, facilitating the adoption and monetization of distributed energy transactions and exchanges, both energy flows as well as financial transactions. This may help reduce transactive energy costs and increase the security and sustainability of distributed energy resource (DER) integration, helping to remove barriers to a more decentralized and resilient power grid. This paper explores the application of blockchain and smart contracts to improve smart grid cyber resiliency and secure transactive energy applications.
Abstract Blockchain as an engine for auto‐enforceable smart contracts could disrupt traditional governance structures by reducing bureaucracy through lower transaction costs, solving principal–agent issues, and subsequent moral hazard. While machine consensus can radically reduce transaction costs and disrupt traditional governance structures, there is a gap between initial conceptualizations of blockchains and their first instantiations. First use cases show that as circumstances change, protocols can become inappropriate for the new environment and require modification. Modification of blockchain code happens through majority consensus, but reaching consensus in a distributed multi‐stakeholder network with sometimes unaligned interests is complex, potentially introducing new agency issues.
Abstract The blockchain innovation appears to represent viable catalysts for achieving global sustainable development targets. Projects and initiatives seeking to extend the reach of distributed ledger technologies (DLTs) seem mostly intended for the benefit of for‐profit businesses, governments, and consumers. DLT projects devised for the public good could aim, in theory, to fulfill the United Nation’s current sustainable development goals. Blockchain technology is being applied in ways that could transform this ambition for good into a practical reality.
Harish Sukhwani, José Manuel Martínez, Xiaolin Chang, Kishor S. Trivedi · 5 authors
While Blockchain network brings tremendous benefits, there are concerns whether their performance would match up with the mainstream IT systems. This paper aims to investigate whether the consensus process using Practical Byzantine Fault Tolerance (PBFT) could be a performance bottleneck for networks with a large number of peers. We model the PBFT consensus process using Stochastic Reward Nets (SRN) to compute the mean time to complete consensus for networks up to 100 peers. We create a blockchain network using IBM Bluemix service, running a production-grade IoT application and use the data to parameterize and validate our models. We also conduct sensitivity analysis over a variety of system parameters and examine the performance of larger networks
ABSTRACT The blockchain has enabled the successful creation of decentralized digital currency networks. This success has prompted further investigation into the usefulness of blockchains in other business settings. Because of the blockchain's use as a ledger, the question arises whether the blockchain could become a more secure alternative to current accounting ledgers. We show that this is infeasible. By casting this question in the context of the Byzantine Generals Problem, which the blockchain was designed to solve, we identify multiple flaws hindering implementation of the blockchain as a financial reporting tool. Whereas blockchain-based digital currencies only exist within the blockchain, economic transactions exist outside of accounting records. This distinction prevents an acceptable level of transaction verification using the blockchain model. Additionally, the security benefits of the blockchain that render it ostensibly immutable are not fully available or reliable in an accounting setting.
Julia Kokina, Rubén Mancha, Dessislava A. Pachamanova
ABSTRACT Blockchain is a distributed ledger technology poised to transform the accounting practice. In this paper, we provide an initial examination of the technology itself and discuss the associated opportunities and limitations. We also present an overview of the current blockchain-related practices in large accounting firms and trace significant milestones in this technology's emergence. Finally, we discuss some potential areas that future research could address.
Blockchain technologies is one of the most popular issue in recent years, it has already changed people's lifestyle in some area due to its great influence on many business or industry, and what it can do will still continue cause impact in many places. Although the feature of blockchain technologies may bring us more reliable and convenient services, the security issues and challenges behind this innovative technique is also an important topic that we need to concern.
Bitcoin has advanced as the most fruitful cryptographic currency in history. Since its launch in 2009.Bitcoingrewtocomprisebillionsofdollarsofecono mic value. Since then a lot of literature has been identified with concealed-but-vital properties of the system, exposed attacks, proposed promising alternatives, and singled out dif challenges. This paper threw light to many related cryptocurrencies or 'altcoins' and enables a more insightful analysis of Bitcoin's properties. The researcher maps the space for providing analyses for bitcoin mining, bitcoin protocol, and bitcoin value determinations.This paper surveys the anonymity in Bitcoins and provides an insight into the framework for analysing the mining hardware, the calculation of Bitcoin value by reviewing various literatures and websites related to Bitcoins.