Alexander Chepurnoy, Mario Larangeira, Alexander Ojiganov
Bitcoin is the first successful decentralized global digital cash system. Usefulness of the mining process requiring a lot of computational resources to be wasted, though, remains disputable. One of possible alternatives for useful Proof-of-Work schemes, Permacoin, is using non-interactive proofs of a static dataset retrievability thus providing a mechanism to store a huge dataset being spread across miners collectively.
In this paper we present a new consensus protocol for Bitcoin-like peer-to-peer systems, where the right to generate a block is given to the party which provides non-interactive proofs of retrievability for the past state snapshots. This Proof-of-Work scheme has better resistance to specialized hardware than Bitcoin and Permacoin. Unlike blockchain systems being used today, a network using the protocol of ours is safe if majority of nodes are rational in terms of storing full blocks. By using that we also show that one useful application of our protocol is the construction of a prunable blockchain system without a security loss.
Alexander Chepurnoy, Mario Larangeira, Alexander Ojiganov
Bitcoin is the first successful decentralized global digital cash system. Its mining process requires intense computational resources, therefore its usefulness remains a disputable topic. We aim to solve three problems with Bitcoin and other blockchain systems of today by repurposing their work. First, space to store a blockchain is growing linearly with number of transactions. Second, a honest node is forced to be irrational regarding storing full blocks by a way implementations are done. Third, a trustless bootstrapping process for a new node involves downloading and processing all the transactions ever written into a blockchain. In this paper we present a new consensus protocol for Bitcoin-like peer-to-peer systems where a right to generate a block is given to a party providing non-interactive proofs of storing a subset of the past state snapshots. Unlike the blockchain systems in use today, a network using our protocol is safe if the nodes prune full blocks not needed for mining. We extend the GKL model to describe our Proof-of-Work scheme and a transactional model modifications needed for it. We provide a detailed analysis of our protocol and proofs of its security.
Bitcoin mining presents a significant economic incentive for efficient hashing and broadcast of data, both parameters stemming from the Proofs of Work used to advance the network. This incentive has led to the development of Bitcoin specific application specific integrated circuits and centralized mining pools, undermining the decentralized motivations behind Bitcoin's design. In addition, the imminent block reward halving threatens the profitability of mining at any scale. Some work has been done in formal models for miner profitability, but existing models do not account for conditions such as the pricing of off-peak power and diverse investment strategies regarding sunken costs. There is also a lack of formal study of how the profit model changes as mining scales from the individual to the industrial level. Given the lack of analysis of these conditions, there are alternative models for profitable or net zero mining that operate at smaller, and therefore more desirable, scale.
O Bitcoin e um sistema de pagamento totalmente digital independente de uma entidade centralizadora como bancos ou governos. O projeto foi criado e publicado em 2008 atraves da Internet. Entretanto apenas em 2009 a rede tornou-se operacional. O Bitcoin e um protocolo de codigo aberto e uma rede ponto a ponto de participantes que e responsavel pelo funcionamento do sistema. Seguranca criptografica, ausencia de taxas e de custos de instalacao sao fatores que convenceram varias empresas do mundo a adota-lo como alternativa de pagamento. Apesar dos trabalhos acerca da moeda digital, pouco ainda se sabe sobre sua topologia e caracteristicas, principalmente pela otica de ciencia de redes. Nesse sentido, o presente trabalho apresenta o estudo da dinamicidade de suas principais variaveis no seu funcionamento diario. No decorrer do trabalho sao apresentadas duas formas de extracao de dados da rede Bitcoin para futuras analises.
In this explorative study, we examine the economy and transaction network of the decentralized digital currency Bitcoin during the first four years of its existence. The objective is to develop insights into the evolution of the Bitcoin economy during this period. For this, we establish and analyze a novel integrated dataset that enriches data from the Bitcoin blockchain with off-network data such as business categories and geo-locations. Our analyses reveal the major Bitcoin businesses and markets. Our results also give insights on the business distribution by countries and how businesses evolve over time. We also show that there is a gambling network that features many very small transactions. Furthermore, regional differences in the adoption and business distribution could be found. In the network analysis, the small world phenomenon is investigated and confirmed for several subgraphs of the Bitcoin network.
Bitcoin is a peer to peer decentralized virtual currency, released online through a research paper in 2008 by the unknown Satoshi Nakamoto . Around the world, many countries have cautiously taken minor initiatives to address the regulatory issues, due to its rising popularity. The regulation is not seen as complete, due to the nascent and novel outlook of bitcoins, requiring time for analysis and empirical evidence. The main research question that needs to be answered, is how can governance ideas be conceptualized to support technological decentralization while protecting against illegal activities? To answer this question a literature review is performed across academia, digital media and conferences/ independent authors. From this study, ideas for frameworks are consolidated, to effectively regulate bitcoins through coalitions, analyzed with game theory. This is complemented with a theoretical understanding of the technical, political, economical and ethical issues surrounding the bitcoin ecosystem. The thesis is broadly divided into seven chapters, where initially an introduction is presented which presents the structure of the thesis, along with the research problem and its motivation. This is followed by an exploration of bitcoin's current framework, which forms the most important theoretical part of the thesis. Here, its system design, strengths, challenges and solutions to regulatory issues are detailed. Also, how bitcoin is being perceived globally across twenty nations, is presented. Being an economic system, there has been reasonable skepticism, as to its validity as a money system. This is presented in the next chapter, where its economic structure is first explored, which is followed by an analysis of bitcoin from the perspective of both Austrian economics and Keynesian economics. Further, to understand the overall validity of a new system, the ethical impacts must be considered. This has been analyzed through two frameworks in this thesis. Firstly, as a large social experiment and secondly through a standard ethical impact assessment. Also, bitcoin has always been portrayed in the popular press, as promoting only decentralization. This is critically analyzed, from classical ideas of noted humanitarian M.K Gandhi and British economist M.F Schumacher. As a follow up, a modern exponential technology framework presented by Singularity University, is offered as a comparison. It is observed that bitcoin excels in the material aspect of decentralization (while requiring centralized intermediaries), but struggles in the spiritual aspect, as detailed. The major regulatory solution offered in this thesis, is through coalitions among stakeholders. For clarity, seven crisis situations are highlighted with the different payoff's (relative power) among the different members assigned, with proper reasoning and a demo game explained. Finally, conclusions and favorable recommendations are drawn , along with sections on research limitations, future research and reflections. Also, an appendix section on the major digital media outlook, is presented for two years (Aug'13- Sep'15), to explain its popular portrayal and the opinion of the general audience. Overall, it can be said that it is still early days for bitcoin and there are major critics in every domain. Consistent issues with taxation, anonymity tools like TOR promoting illegal activities, its inherent economic value and price volatility exist. The internet as an information medium, is probably the only suitable precedent for bitcoin which has been far more successful than anticipated. The benefits of bitcoin from exponentially lower transaction fees, global banking outreach, framework for decentralized asset ownership transfer and its ability to impact the Monetary Policy of ruling governments have been appreciated. Further, as a practical lesson, policy makers could see mainstream bitcoin as promoting a balance of centralized and decentralized intermediaries. Any effort at promoting an extreme ideology could have long term negative effects. Also, offering technologies like bitcoin a fair trial run would be far more appropriate than inviting legally controversial use. With over hundred competing digital currencies, the question is certainly not if, but when they would be competitive with fiat currencies.
<ns4:p>Trust in scientific research is diminished by evidence that data are being manipulated. Outcome switching, data dredging and selective publication are some of the problems that undermine the integrity of published research. Methods for using blockchain to provide proof of pre-specified endpoints in clinical trial protocols were first reported by Carlisle. We wished to empirically test such an approach using a clinical trial protocol where outcome switching has previously been reported. Here we confirm the use of blockchain as a low cost, independently verifiable method to audit and confirm the reliability of scientific studies.</ns4:p>
Eleftherios Kokoris-Kogias, Philipp Jovanovic, Nicolas Gailly, Ismail Khoffi · 6 authors
While showing great promise, Bitcoin requires users to wait tens of minutes\nfor transactions to commit, and even then, offering only probabilistic\nguarantees. This paper introduces ByzCoin, a novel Byzantine consensus protocol\nthat leverages scalable collective signing to commit Bitcoin transactions\nirreversibly within seconds. ByzCoin achieves Byzantine consensus while\npreserving Bitcoin's open membership by dynamically forming hash\npower-proportionate consensus groups that represent recently-successful block\nminers. ByzCoin employs communication trees to optimize transaction commitment\nand verification under normal operation while guaranteeing safety and liveness\nunder Byzantine faults, up to a near-optimal tolerance of f faulty group\nmembers among 3f + 2 total. ByzCoin mitigates double spending and selfish\nmining attacks by producing collectively signed transaction blocks within one\nminute of transaction submission. Tree-structured communication further reduces\nthis latency to less than 30 seconds. Due to these optimizations, ByzCoin\nachieves a throughput higher than PayPal currently handles, with a confirmation\nlatency of 15-20 seconds.\n
Although it is still in early stages, many commentators have been quick to note the revolutionary potential of next-generation or Bitcoin 2.0 technology. While some have expressed fear that the widespread application of these technologies may engender the rise of a Terminator-style Skynet, others believe that it represents the coming of a decentralized autonomous society (DAS) in which humans are freed from centralized forms of power through the proliferation of distributed autonomous organizations or DAOs. Influenced by neoliberal theory that stresses privatization, open markets, and deregulation, Bitcoin 2.0 technologies are implicitly working on the assumption that 'freedom' means freedom from the state. This neglects, however, that within capitalist societies, the state can also provide freedom from the vagaries of the market by protecting certain things from commodification. Through an analysis of (1) class and the role of the state; (2) the concentration and centralization of capital; and (3) the role of automation, I argue that the vision of freedom that underpins Bitcoin 2.0 tech is one that neglects the power that capital holds over us in both organizing the structure of our lives, and informing our idea of what it means to be human. In neglecting these other forms of power, I claim that the DAS might be a far more dystopian development than its supporters comprehend, making possible societies that are commodities all the way down.
version anglaise de Crowdfunding baseado em blockchain: qual seu impacto sobre a produção artística e o consumo de arte?, Observatorio/ITAU cultural,n°19
The money is a widely accepted commodity, by means of which it is possible to determine the economic value of purchased goods and services and make payments. Over the centuries, "money" has evolved many times. Their constantly changing character, generates questions on their future aspect. In the reference to the cryptocurrencies questions are focused on their nature and compliance with the definition of money.
Virtual currencies have recently become one of the most popular topics in the media. This paper focuses on economic aspects of Bitcoin, being an attempt to answer the question if Bitcoin can be considered money in the light of economic theories of money. On the basis of the reports published by the European Central Bank and the Financial Action Task Force, as well as the available Internet and primary sources, there have been presented the types, history and functioning of virtual currencies. The knowledge of virtual currencies makes it possible to foresee the problems arising from their existence, such as possible threats to international security, difficulties with taxation etc. The growing popularity of virtual currencies and cryptocurrencies is linked with the increase of importance of non-cash payments on global scale. Thus, Bitcoin may be considered next step in the evolution of digital money.
In the past decade, blockchain technology has garnered significant attention from a diverse array of industries. Despite the fact that blockchain technology was initially developed for the Bitcoin P2P cryptocurrency network, there has been a recent surge in interest in its potential integration with other service sectors. In the domain of machine-to-machine commerce, distributed ledger technologies, as seen in blockchain systems, have recently been hailed as potential platforms. A decentralised network architecture, security, immutability, and transparency are among the primary attributes of blockchains. The unalterable nature of blockchain ledgers enables members to rely on one another, thereby increasing performance and participation. Scalability and security are substantial challenges for blockchain technology. This study provides a comprehensive analysis of the emergence of blockchain technology and various methods for addressing the scalability issues associated with distributed ledgers
Bitcoin is the first decentralized peer-to-peer (P2P) electronic currency. It was created in November 2008 by Satoshi Nakamoto. Nakamoto released the first implementation of the protocol in an open source client software and the genesis of bitcoins began on January 9th 2009. The Bitcoin protocol is based on clever ideas which solve a form of the Byzantine Generals Problem and sets the foundation for Decentralized Trust Protocols. Still in its infancy, the currency and the protocol have the potential to disrupt the international financial system and other sectors where business is based on trusted third parties. The security of the bitcoin protocol relies on strong cryptography and one way hashing algorithms.
The paper examines decentralized cryptocurrency protocols that are based on the use of internal tokens as identity tools. An analysis of security problems with popular Proof-of-stake consensus protocols is provided. A new protocol, Interactive Proof-of-stake, is proposed. The main ideas of the protocol are to reduce a number of variables a miner can iterate over to a minimum and also to bring a communication into block generation. The protocol is checked against known attacks. It is shown that Interactive Proof-of-stake is more secure than current pure Proof-of-stake protocols.
Derzeit wird in technisch-orientierten Kreisen häufig über das “The Next Big Thing” diskutiert. Wie Facebook die Massenmedien verändert hat und sehr wichtig fürs Marketingfeld geworden ist, können auch die Kryptowährungen ihre Stelle im internationalen Handel finden. Diese Masterarbeit konzertiert sich auf die Kryptowährungen und ihre Eigenschaften im Zusammenhang mit internationalem Business. Im ersten Teil dieser Masterarbeit wurden mehrere Vorteile für Unternehmen dargestellt. Die Hindernisse, die der weiteren Verbreitung schaden, können in diesem Teil auch gefunden werden. Die Literaturrecherche ergab mehrere IT,- und Währungsakzeptanzmodellen. Je nach den Faktoren aus diesen Modellen und Kommentaren vom Luther, wurden die Treiber, die für die Verwendung von Kryptowährungen sprechen, geschildert. Diese Arbeit ist in Form einer vergleichenden Fallstudie mit qualitativen Expertenbefragungen ausgearbeitet. Diese Forschungsstrategie ermöglichte die aktuelle Situation, Vorteile, Nachteile und Treiber aus den Akzeptanzmodellen, anhand von PraxisErfahrungen, zu beschreiben. Basierend auf diesen Befragungen, ein überarbeitetes Akzeptanzmodell wurde dargestellt und die Propositionen getestet Die geringe Anzahl der Befragten erlaubt keine konkreten Kausalbeziehungen zu ziehen. Daher wurden nur die Propositionen getestet. Die Ergebnisse haben gezeigt, dass die Kryptowährungen sehr gute Chance haben, ein wichtiges Instrument für Wertübertragung zu werden. Nicht nur die Kryptowährungen, sondern auch die grundlegende Architektur, sprich Blockchain, scheint auf Akzeptanz zu gewinnen. Die Experten waren sich bzgl. der Zukunft einig. Die derzeit Nummer 1 Kryptowährung Bitcoin, wird durch technologisch fortgeschrittene Währungen in kommenden Jahren ersetzt. Des Weiteren wurde auch der slowakische und österreichische Markt untersucht. Es wurden keine markanten Unterschiede zwischen diesen beiden Ländern festgestellt. In beiden Ländern spielen die sozialen Normen eine wichtige Rolle. (im Zusammenhang mit Akzeptanz von neunen Währungen und Technologien) Außer von sozialen Normen, gibt es auch andere Treiber wie wahrgenommene Handhabung, wahrgenommene Nützlichkeit, Möglichkeit des Ausprobierens, Beobachtbarkeit und die unterstützenden Bedingungen bzw. die Architektur, 97 die für Verwendung der Kryptowährungen sprechen. Die Ergebnisse dieser Masterarbeit haben die wichtige Rolle von Kryptowährungen im internationalen Handel bestätigt. Es ist nur Frage der Zeit, bis die Kryptowährungen auch in täglichem Leben verwendet werden.
This document established the main factors of bitcoin risk perception based on the explorative factor analysis, then studied them using structural equation model and conducted one-order and second-order confirmatory factor analysis. The results show that the bitcoin perceived risk mainly includes four aspects: bitcoin technology and security risk, national policy and legal risks, social risks, bitcoin market and transaction risk, the risk perception has correlation on each other. Based on the model, the author put forward the corresponding policy recommendations.