The first chapter examines whether Bitcoin, the most popular cryptocurrency, is a good investment vehicle for diversifying an investment portfolio by testing its systematic risk. The chapter also estimates the optimal proportion of Bitcoin that should be included in an investment portfolio. The observation period in this chapter is between 7/20/2010 and 6/30/2014, and a wide range of regions are examined around the world. The Capital Asset Pricing Model and the Fama-French Three Factor Model are used to examine the systematic risk of Bitcoin, and the optimal proportion of Bitcoin in an investment portfolio is estimated by the mean-variance portfolio analyses. The results show that Bitcoin is a non-systematic risk asset around the world markets so that Bitcoin can be used to diversify the risk in an investment portfolio. Besides, The mean-variance portfolio analyses suggest that the optimal proportion of Bitcoin in an investment portfolio is between 4.4\% and 21.5\%. In the second chapter, the Autoregressive Distributed Lag cointegration with bounds test approach and the unrestricted vector autoregressive model with Granger causality tests are applied to identify the determinants of Bitcoin price movement. The time series daily data from 8/17/2010 to 1/8/2016 is used in this chapter. The control variables include the supply and demand fundamentals of Bitcoin, macro economic indicators, and investor's attractiveness of Bitcoin. The results confirm the existence of Bitcoin price equilibrium in the long run. In the short run, the price of Bitcoin is affected by its supply and demand fundamentals such as Bitcoin US exchange trade volume and the number of transaction in Bitcoin. In addition, the findings suggest that the causality between Bitcoin price and its supply and demand fundamentals are bi-directional. The third chapter studies the liquidity of Bitcoin using the time series daily data over the period 1/1/2014 to 12/31/2015. Based on the available data for Bitcoin, five liquidity measures are chosen to evaluate the liquidities of five Bitcoin exchange companies and different size of stocks. The results suggest that the liquidity of Bitcoin is sensitive to the choice of the Bitcoin exchange company. The Bitcoin exchange company called Bitfinex provides the highest liquidity for Bitcoin trading. Moreover, the results indicate that stocks are more liquid than Bitcoin no matter the market capitalization sizes of stocks.

Denna uppsats undersöker nyttan som uppfylls i bytesmedlet Bitcoin i förhållande till densvenska kronan i allmänhet och de makroekonomiska konsekvenserna av sådannyttouppfyllelse i synnerhet. Undersökningen utgår från att nyttan som kan härledas urpengar kommer av dess inneboende kvalitéer, främst i form av dess möjligheter att bevaravärde i samt dess möjligheter att generera låga transaktionskostnader. Undersökningenfinner att det finns möjligheter för Bitcoin att generera högre nytta än den svenska kronanunder vissa omständigheter. Detta främst i avseendet värdelagring till följd av denregelföljda penningmängdsutveckling som Bitcoin karaktäriseras av och i tider där densvenska kronans monetära bas expanderas när penningpolitik förs och inflation uppstårsom följd. I sådana tider finner undersökningen att Bitcoins ökade nytta i jämförelse medden svenska kronan skapar incitament för individer att byta valuta från den svenskakronan till Bitcoin om vinsterna i nytta är stor nog. I detta uppkommer den centralaanalysen om huruvida Bitcoin och dess användning introducerar systemrisker i denmakroekonomiska politiken. Om det finns en god och lättillgänglig möjlighet att bytavaluta när penningpolitik skapar inflation i den svenska kronan kan också risk finnas attpenningpolitiken misslyckas. Detta till följd av det köpkraftsbortfall som sker i densvenska kronan när dess efterfrågan minskar om människor byter valuta. Undersökningenfinner att resultatet beror på vilket teoretiskt perspektiv som anläggs i analysen och att detfaktiskt råder tydliga systemrisker av Bitcoin i ett keynesianskt perspektiv, medanmotsatsen, att systemriskerna finns inneboende i den svenska kronan och att Bitcoin kanvara en väg från dessa systemrisker, är slutsatsen av en analys utgående från denösterrikiska konjunkturcykelteorin. Trots de uppfattade systemriskerna med enkeynesiansk syn, föreslås reformer för att Bitcoin ska kunna samexistera medkeynesianska penninginstitut för att kunna ta vara på den nytta som kan resultera avBitcoins användning som bytesmedel. / This paper investigates the fulfillment of utility in the currency Bitcoin in relation to the Swedish krona in general andthe macroeconomic consequences of such fulfillment of utility in particular. The paper starts with the assumption thatthe utility generated by money is deduced from its qualities, mainly the quality in storage of value and the currency´spossibilities of generating low transaction costs. The investigation finds that there are possibilities that Bitcoin maygenerate a higher utility for its users than the Swedish krona under some circumstances. This mainly from Bitcoinsqualities in storage of value due to its predetermined change in money supply and in times when the Swedish krona´smonetary base is expanded by monetary policy and its subsequent inflation. In such periods when monetary expansionis undergoing in the Swedish krona, the investigation finds that the expected higher utility in Bitcoin in relation to theSwedish krona may cause a change of individuals incentives for currency, away from the Swedish krona and towardsBitcoin, if the profit gained from such change for an individual is great enough. From this, the central analysis ofBitcoins consequences on macroeconomic level follows. If there is an opportunity to change currency, which causesutility profits for individuals, there is also risk that the stimulus in monetary policy fails. This due to the decrease ofpurchasing power in the Swedish krona due to the lower demand of the currency in question subsequent to its loss init’s quality of storage of value. The analysis finds that depending on which theoretical perspective that is used, systemicrisks stemming from Bitcoin usage can be found in an analysis made with the Keynesian perspective. This while theopposite, that the systemic risks are introduced in the economy with the Swedish krona, is the result of an analysis madewith the Austrian theory of business cycle. Even with the systemic risks identified in the Keynesian analysis, reformsare suggested so that Bitcoin is able to co-exist with Keynesian monetary institutions to be able to take care of the utilitygained on the microeconomic, individual level that may result from Bitcoins usage as means of trade.

The main objective of this diploma thesis is to introduce the history and origin of digital currency Bitcoin and how this project works specifically from the perspective of IT. The thesis contains detailed instructions for the process of implementation Bitcoin payments to the company. This diploma thesis describes the possibilities of abuse and security. Further compares advantages and disadvantages with the classical exchange resources. How is it possible to get this currency, use and how it developed its rate against other world currencies. The thesis also mentions similar cryptocurrencies.

Sammanfattning   Examensarbete i företagsekonomi III, Ekonomihögskolan vid Linnéuniversitetet i Kalmar, Ekonomistyrning, 2FE71E, VT 2014. Författare: Eric Paulsen, Simon Perchun Handledare och examinator: Thomas Karlsson & Petter Boye Titel: Bitcoin - Risk eller möjlighet?   Bakgrund: Den digitala kryptovalutan har idag blommat upp där Bitcoin står i fokus. Något som blivit uppmärksammat i bland annat media och genom politiska uttalanden. Detta har fått företag till att applicera Bitcoin som möjligt betalsätt utöver de vanliga betalmöjligheterna som exempelvis kortbetalningar.   Syfte: Syftet med denna uppsats är att efter insamling av empiri kunna beskriva genom vår utvalda teoretiska referensram varför företag väljer att acceptera Bitcoin som möjligt betalmedel, samt vilka möjligheter och risker som finns förenade inom företagsbranschen, och sedan förklara vidare hur företagen hanterar dessa möjligheter och risker.   Metod: För att kunna uppfylla syftet med studien så har vi utgått från en abduktiv metodsyn. Vi har samlat in empiri i form av semistrukturerade kvalitativa intervjuer från sex olika företag som mottar Bitcoin som möjligt betalsätt. Det material som samlats in förklaras sedan utifrån vår teoretiska referensram för att kunna uppfylla syftet med studien.   Slutsats: Vi kom till slut fram till att Bitcoin ger företag stora möjligheter i förhållande till den lilla risk de utsätter sig för. En ny betalmöjlighet som kan leda till konkurrensfördelar.   Nyckelord: Bitcoin, ekonomi, kryptovalutor, risk, möjligheter.

The aim of this study was to illustrate an unexplored illegal exploitation of legal businesses, with the purpose of limiting this market and especially the related transactions. The issue of transactions regarding illegal material executed with credit cards was solved through involving the companies who issues the credit cards, making the market more transparent and thus preventing this kind of transactions. The thesis will illustrate how cryptocurrencies, such as Bitcoin, are being exploited regarding illegal transactions and more specifically, transactions regarding selling and purchasing Child Abusive Material within file hosting services (cyberlockers). The analyzed data was gathered using a webcrawler and different methods for analyzing correlation were implemented on the data to find relationships between different data points. The data points were then clustered, using an algorithm to create a relationship network. The developed model analyzed the data to identify trends and patterns regarding the illegal transactions and the results can be used to find the most prominent users who are potential perpetrators that actively distributes illegal material. A deeper analysis is then performed on the, according to the model, most interesting users in an attempt to identify their underlying identity. When cryptocurrencies are used by perpetrators to pay and get paid for illegal material, the transaction flows cannot immediately be connected to specific identities and therefore it is required to first identify potential perpetrators and track their transactions, to later compare them with the transactions that has already been identified as payments for illegal material. Apart from this model, a framework has been created to identify certain patterns and trends regarding the cyberlockers’ transaction flows. This was performed through analysis of the transaction flows connected to cyberlockers that were suspected to contain Child Abusive Material or other illegal material. With the results from the first and second model, the most interesting cyberlockers for future investigations were discovered, according to the trends and patterns in their surrounding transaction flows. When that analysis was performed and the first model was implemented, potential perpetrators was identified through collaborations between the investigating unit, the Police, the cyberlockers in question and the relevant exchange services. Through this collaboration the identities of the perpetrators are revealed and the transaction flows can then be analyzed to limit further distribution of Child Abusive Material within cyberlockers and consequently limit the illegal transactions with cryptocurrencies. Keywords: Bitcoin, Child Abusive Material, Cyberlockers, Illegal payments, Cryptocurrency, Webcrawler, Correlation, Relationship network.

Bitcoin is a new digital, virtual currency. Unlike other currencies, it is not controlled by a single company, financial institution or government. Instead, it is controlled by a peer-to-peer network of clients running the open-source Bitcoin software. When using Bitcoin, online transactions can be made directly between two parties without the need for a trusted third party such as Paypal, Visa or a bank. This paper describes the development of Bitcoin NFC, an Android app designed to send bitcoins from one Android device to another. The technology used for sending information between devices is Near Field Communication (NFC), a very close-ranged wireless protocol. NFC allows devices to communicate by simply touching two devices together. There is no need for any configuration or pairing. Bitcoin NFC makes it possible to use bitcoins for point-of-sale transactions. Rather than swiping a credit card, a phone running Bitcoin NFC could be swiped instead. / text

I dagens samhälle används en mängd metoder och verktyg för att nå kunder och eftersom konkurrensen är knivskarp är det extra viktigt att skapa personliga relationer till sina kunder. Syftet med denna uppsats är att studera bitcoin, en virtuell valuta, som ett verktyg för att skapa, underhålla och fördjupa dessa relationer. Bitcoin accepteras idag som betalningsmedel av en mängd olika företag och det är därför intressant att undersöka varför de gör detta. Genom att utföra en enkätstudie och intervjuer kan det konstateras att användningen av bitcoin bland företag har ökat stadigt det senaste halvåret. Det visar sig också att företagen använder sig av bitcoin som marknadsföringsverktyg på två olika sätt; dels som ett betalningsalternativ inom traditionell butikshandel men också som en belöning inom ett lojalitetsprogram. Det kan konstateras att företagen använt bitcoin som ett verktyg för att komma i kontakt med nya kunder och för att utmärka sig inom sin bransch. Dock använder företagen inte bitcoin som ett verktyg för att bygga långvariga relationer. Därför är slutsatsen att bitcoin inte används på ett relationsmarknadsföringsmässigt sätt och således inte heller leder till några förstärkta kundrelationer.

Since the introduction of Bitcoin, numerous studies on Bitcoin mining attacks have been conducted, and as a result, many countermeasures to these attacks have been proposed. The reputation-based mining paradigm is a comprehensive countermeasure solution to this problem with the goal of regulating the mining process and preventing mining attacks. This is accomplished by incentivizing miners to avoid dishonest mining strategies using reward and punishment mechanisms. This model was validated solely based on game theoretical analyses and the real-world implications of this model are not known due to the lack of empirical data. To shed light on this issue, we designed a simulated mining platform to examine the effectiveness of the reputation-based mining paradigm through data analysis. We implemented block withholding attacks in our simulation and ran the following three scenarios: Reputation mode, non-reputation mode, and no attack mode. By comparing the results from these three scenarios, interestingly we found that the reputation-based mining paradigm decreases the number of block withholding attacks, and as a result, the actual revenue of individual miners becomes closer to their theoretical expected revenue. In addition, we observed that the confidence interval test can effectively detect block withholding attacks however, the test also results in a small number of false positive cases. Since the effectiveness of the reputation-based model relies on attack detection, further research is needed to investigate the effect of this model on other dishonest mining strategies. / Includes bibliography. / Thesis (MS)--Florida Atlantic University, 2021. / FAU Electronic Theses and Dissertations Collection

Magíster en Ciencias, Mención Computación. Ingeniero Civil en Computación / Every time we place a bet, we implicitly trust the other participant to pay in the case we win. For this reason if we deal with people we do not know or trust, we do not bet directly with them, and instead we use a casino or other gambling sites. We expect the law or even casino reputation to help us to enforce good behavior. Cryptocurrencies made possible to store and transfer value easily without using centralized control. Given its recent popularity, many decentralized applications have been proposed and implemented on top of them. Among them, gambling. It is currently possible to safely bet with a stranger on random events using cryptocurrencies. We can bet on the value of digital dice, cards or roulette. Neither trust nor centralized entities are required. In this work we propose a protocol on top of Bitcoin to place bets on real world events in a decentralized and trustless fashion. Our protocol uses a set of oracles to bring the outcome of the event on which the bet depends into the blockchain. When a certain threshold of the oracles have reported the same outcome for the event, we unlock the winner s prize. The protocol was designed to automatically move the money to one of the players in that case, so oracles do not take control of the prize, they only decide between two possible outcomes. Economic incentives are placed to encourage good behavior on the participants. Oracles get paid if and only if they provide the right answer, where right is defined as the answer provided by the majority of them. Also, oracles are required to place a deposit to participate. This allows the protocol to establish economic penalties if the oracle fails to answer. Once the bet is placed, the prize is locked waiting for the oracles answer. Players relinquish their control over the money until the oracles decide the winner or a previously defined ti- meout expires. In case of timeout, each player gets half of the prize. Using Bitcoin scripting language, the protocol guarantees fairness and execution correctness with both, a dishonest minority of oracles as well as a dishonest peer, at least once the bet is placed. Before that a dishonest peer can cause limited economic damage to an honest player. Yet the attack produces no net gain: it costs the attacker as much as the amount of the damage done to the victim. Dishonest oracles, before the bet is placed, can cause small economic damage to both players equally, although the cost for this attack is a parameter set by the players. The protocol was implemented and run in the Bitcoin testnet using the official client to ve- rify the transactions. Our implementation is currently available as an Open Source project. Discussion on the trade off between the protocol cost and economic incentives for the par- ticipants are included in this work. We also provide a detailed cost analysis of running the protocol. We believe this work s contribution is a novel way of reasoning and deciding about real world events while integrating the outcome into the blockchain. The protocol can be ea- sily extended to resolve contract disputes and similar situations where subjective but fair resolutions are needed, all in a decentralized environment.

Yes / Amid its rapidly increasing usage and immense public interest the subject of Bitcoin has raised profound economic and societal issues. In this paper we undertake economic and econometric modelling of Bitcoin prices. As with many asset classes we show that Bitcoin exhibits speculative bubbles. Further, we find empirical evidence that the fundamental price of Bitcoin is zero.