With the explosion of Bitcoin, various cryptocurrencies are beginning to garner incredible amounts of attention from speculators and institutional investors alike. Simultaneously, the rise in the number of occurrences of cyber ransom attacks has proven to be an increasingly relevant part of the conversation in the formative years of the Bitcoin ecosystem, as hackers demand payments be in the form of bitcoin. To test the relative impact of these different ransom events on the price of bitcoin, this paper conducts an event study to quantify the reaction by investors upon revelation of the news. In addition, it examines differences between Bitcoin and two other cryptocurrencies, Ethereum and Litecoin, to control for any liquidity effects of victims buying up large sums of bitcoin. The findings of the study indicate that following the ransom events there is a positive price reaction, supporting the claim that investors in Bitcoin generally perceive these events as good news. This could have a profound effect on the development and further adoption of cryptocurrencies, as regulators try to determine whether or not to intervene.

Bitcoin is a cryptocurrency that has been the focus of a lot of discussions lately and has attracted a large number of users. Its offers many possibilities for cheap transactions and unregulated finances which has been realized in numerous sites and applications on the web and in mobile phones. One medium that seem to have been neglected when it comes to Bitcoins development is email. This is curious since Bitcoin by its nature seem to have many properties that would work well with texted messages. The purpose of this study it to analyze the current papers about Bitcoin to find the current status of email based Bitcoin services,  and try to analyze if email as a tool is a suitable medium to be used with Bitcoin. This analyze is done through a systematic literature review of current papers, followed by an examination of past and current Bitcoin companies that has used email as part of their service. In the end the results suggested that the low security in email, and the apparent lack of services that would benefit from an email based Bitcoin service suggest that a service like that would be hard to develop today and not very useful to the public.

The aim of this thesis is to describe the basic functional principles of digital cryptocurrencies and its economical and legal aspects. Digital cryptocurrencies are young and dynamic phenomenon in financial transactions, which represents an alternative to the traditional national currencies. This thesis is divided into three main parts. In the first part the digital currencies and its function is discussed, the economical aspects of digital currencies and its impact on the theory of money are the main theme of the second part. The final, third part is discussing the legal aspects of digital currencies within the Czech legal system. The first part of this thesis introduces digital currencies, the operation of the whole system and also the basic terminology related to the digital currencies, which is necessary for understanding the subject. These essential aspects and features are being mostly illustrated on the case of the oldest and most famous digital currency - bitcoin - in favour of clarity. The second part of this thesis is discussing the economical aspects of digital currencies. The opening of this part is dedicated to the terminology, particularly terms "money" and "currency". Clear definition of these terms and setting out the differences between them in the sense of economic theory is...

We investigate to which degree one could trace Bitcoin transactions and characterize purchasing behavior of online anonymous marketplaces by exploiting side channels. Using a list of addresses found by the FBI on Silk Road servers, and information on the marketplace's official guides, we infer the role played by each address in the list and classify them based on heuristics. We then attempt to trace Bitcoin transactions and show that the anonymity set size is greatly reduced using product review data and the address classification performed on the previous step. Finally, using clustering techniques based on transaction graph analysis, we assign addresses into user wallets, then group these wallets together based on spending patterns, to be able to characterize purchasing behavior.

This thesis analyzes a continuity between the changes of the exchange rates of the cryptocurrencies and the dynamics of the created content on the Internet by their users. The main goals of this thesis are to analyze unstructured data focusing on the development of the topics for different cryptocurrencies and to interconnect the key topics with the changes of the exchange rates of this cryptocurrencies. In order to successfully obtain goals I describe process and methods of the analysis unstructured data, explain the issues of the cryptocurrencies, identify a source of the downloading data and choose some cryptocurrencies for subsequent analysis. The contribution of this thesis is the identification of the development key topics in the chosen source, finding topics, which are the most under discussion about the chosen five cryptocurrencies. Also this thesis detects the existence of the reaction of the users to the changes of exchange rates of the chosen cryptocurrencies and describes it. Particular contribution of this thesis is a practical demonstration of the application the elected technology for analyzing unstructured data. Also additional contribution is the methods using in the analytical part. Structure of this thesis is divided to the three main parts. The first part describes the analysis of unstructured data theoretically and explain the issues of cryptocurrencies. The second part devotes a draft of the solution for creating an analytical part. The third part maps the most discussion cryptocurrencies in the chosen source, identifies the development of the key topics for five chosen cryptocurrencies Bitcoin, Nxt, Dash, Monero and Counterparty and interconnects the key topics this cryptocurrencies with changes their exchange rates in relation to American dollar.

The main goal of this diploma thesis is to explore the area of virtual currency Bitcoin and assess the use of this currency in today's economy. Thesis first mentions the cryptocurrency market, the technology and other altcoins. It further analyzes the cryptocurrency Bitcoin in detail, its foundation, history and mining. The text also explores the volatility of this currency in the recent years, the question of regulation by states and technological threats to the network. In the final chapter diploma thesis examines the possibilities for individuals to obtain this currency and the use of Bitcoin by enterprises.

abstract: The lack of fungibility in Bitcoin has forced its userbase to seek out tools that can heighten their anonymity. Third-party Bitcoin mixers utilize obfuscation techniques to protect participants from blockchain analysis. In recent years, various centralized and decentralized Bitcoin mixing implementations have been proposed in academic literature. Although these methods depict a threat-free environment for users to preserve their anonymity, public Bitcoin mixers continue to be associated with theft and poor implementation. This research explores the public Bitcoin mixer ecosystem to identify if today's mixing services have adopted academically proposed solutions. This is done through real-world interactions with publicly available mixers to analyze both implementation and resistance to common threats in the mixing landscape. First, proposed decentralized and centralized mixing protocols found in literature are outlined. Then, data is presented from 19 publicly announced mixing services available on the deep web and clearnet. The services are categorized based on popularity with the Bitcoin community and experiments are conducted on five public mixing services: ChipMixer, MixTum, Bitcoin Mixer, CryptoMixer, and Sudoku Wallet. The results of the experiments highlight a clear gap between public and proposed Bitcoin mixers in both implementation and security. Today's mixing services focus on presenting users with a false sense of control to gain their trust rather then employing secure mixing techniques. As a result, the five selected services lack implementation of academically proposed techniques and display poor resistance to common mixer-related threats. / Dissertation/Thesis / Masters Thesis Computer Science 2020

Bitcoin is an asset that demonstrated a high increase in price since it was launched in 2009, meanwhile it has been a very volatile and risky asset. Previous research has indicated that an allocation of bitcoin in investor’s portfolio could increase return as well as risk adjusted return. Furthermore, bitcoin has been observed to be uncorrelated to many markets; creating diversification opportunities and in some instances acted as a hedge against various stock markets. Due to the similarities between bitcoin and gold they have often been compared as alternative investment assets. Therefore, it is of interest for investors to understand if bitcoin could be included into a stock-portfolio in the Swedish market to increase risk adjusted returns and if bitcoin is a better alternative investment, than gold. Furthermore, if bitcoin could be used as hedge against the Swedish stock market. Three different portfolios with bitcoin were created, 1% bitcoin, 4% bitcoin and 8% bitcoin, the rest of the portfolio constitutes of Stockholm gross-index (OMXSGI). The portfolios are compared to OMXSGI and similar portfolios involving gold and OMXSGI. The portfolios are created for four different periods: 2011- 2021, 2016-2021, the bear market during the pandemic and the year 2020. Results reveals that during normal market behavior an 8% allocation of bitcoin and OMXSGI generates the highest Sharpe ratio. Also, that a small allocation of bitcoin can generate higher returns to lower risk then OMXSGI. During normal market behavior portfolio with bitcoin performs higher returns and Sharp ratio than portfolios with gold but to a higher risk. Additionally, bitcoin is not correlated to the Swedish market and implies that it possibly may be used as a hedge during normal market behavior. During the corona bear market bitcoin has a high correlation to OMXSGI and has a similar negative return but to a higher volatility. Meanwhile gold act as a safe haven during turbulent market behavior. To conclude during normal market times bitcoin creates opportunities for investors to include bitcoin to the portfolio. High allocations of 8% bitcoin might be too much risk for risk averse investors. During the corona bear market bitcoin portfolios generates worse returns to a higher risk and gold is a better asset to hold. Bitcoin and cryptocurrencies are assets which have some unique risks that cannot be measured by the Sharp ratio. Thus limit the results and analysis of the study.

Payment settlement systems are constantly developing, however, the emergence of Bitcoin in 2009 created a whole new ball game for regulators. This new type of currency did not play by the same rules as other currencies, with the crypto-currency being borderless (not created by any country) and transferable almost instantaneously. Further, its users remained anonymous. This currency therefore became a breeding ground for illegal activities and disappointment. Users of the currency could use it as a form of payment system for illegal activities, by completely circumventing financial regulators. Other users took advantage of the lack of knowledge surrounding this new type of currency, running Ponzi schemes and defrauding ignorant users of their crypto-currency. Then there were the unfortunate users who, attracted to the notion of reaping large profits from the volatile nature of the currency, often found themselves disappointed when the volatile nature of the currency resulted in large trading losses. Crypto-currency is not all that bad however. Although many risks exist with this new type of currency, there also exist benefits which conventional fiat currency cannot provide. Regulators are therefore placed in a tricky position in which they must try to regulate this new currency to mitigate the possible risks without completely side-lining the benefits posed by the currency. However, regulators cannot create legislation without first understanding how crypto-currency functions. The ever-growing popularity of crypto-currency requires that regulators act fast but also provides many global regulatory lessons which South African regulators can learn from and use in drafting the appropriate legislation. This dissertation considers the nature of this new currency, the way in which it functions and the risks which it comes burdened with, while looking at other regulatory approaches in order to propose legislation which should be adopted in South Africa. / Mini Dissertation (LLM (Banking))--University of Pretoria, 2020. / Mercantile Law / LLM (Banking) / Unrestricted

The thesis explains the main characteristics and cryptocurrency definition. The thesis also offers cryptocurrency awareness analysis of Czech respondents. As part of this thesis there are also described legal and tax environments in the Czech Republic. The thesis focuses on specifics of taxation of income from cryptocurrency transactions. When the tax liability arises, it submits proposals to which category does the income belong and it comprehensively describes the procedure for calculating the tax base and subsequent taxation. In the case of legal entities, it presents the basic procedures for dealing with cryptocurrencies in the company. It deals with the „de lege ferenda“ taxation of income.