The cryptocurrency market is continuously growing but is still a relatively unexplored field within academic research. The ambition with this thesis is to increase existing research on market efficiency of cryptocurrencies, by studying the risk exposure of identical investments between different cryptocurrency exchanges. The study includes four cryptocurrencies and nine different exchanges, the data is tested on a full sample period and two subsample periods. The results reveal significant Sharpe ratio differences for identical investments on selected exchanges, but also improved efficiency between the first and second subsample periods. The study concludes that there are significant market inefficiencies on the cryptocurrency market, but the results also suggests that the market is becoming more efficient over time.

This thesis paper explores the developing technology blockchain by trying to understand the technology from a technical performance standpoint and also understanding the development process of blockchain networks and applications. The first half of this paper analyzes two research papers, "Bitcoing-NG: A Scalable Blockchain Protocol" and "Untangling Blockchain: A Data Processing View of Blockchain Systems," to understand and explain some of the technical differences and shortcomings of blockchain technologies. The second half of this paper then proceeds to develop a private blockchain network on the Ethereum network and deploy a smart contract on that private blockchain network. This process gives insight into the development of blockchain applications and identifies the struggles blockchain developers face.

Distributed ledger technology (DLT) stands to benefit industries such as financial services with transparency and censorship resistance. DLT systems need to be scalable to handle mass user adoption. Mass user adoption is required to demonstrate the true value of DLT. This dissertation first analyses scalability in ethereum and EOS. Currently, ethereum 1.0 uses proof of work (PoW) and handles only 14 transactions per second (tps) compared to Visa's peak 47 000 tps. Ethereum 2.0, known as Serenity, introduces sharding, proof of stake (Casper), plasma and state channels in and effort to scale the system. EOS uses a delegated proof of stake (DPoS) protocol, where 21 super-nodes, termed ‘block producers' (BPs), facilitate consensus, bringing about significant scalability improvements (4000 tps). The trade-off is decentralisation. EOS is not sufficiently decentralised because the BPs yield significant power, but are not diverse. This dissertation conducts an empirical analysis using unsupervised machine learning to show that there is a high probability collusion is occurring between certain BPs. It then suggests possible protocol alterations such as inverse vote weighting that could curb adverse voting behaviour in DPoS. It further analyses whether universities are suitable BP's before mapping out required steps for universities to become block producers (leading to improved decentralisation in EOS)

The cryptocurrencies are growing more and more popular, both due to their independency on institutions and the feeling of anonymity they provide. This is, however, also accompanied by an increasing number of their abuse for criminal activities. This thesis explores the principles of current cryptocurrencies as well as techniques used for increasing anonymity of their usage. Based on the findings, it proposes a solution attemping to deanonymise activity in select cryptocurrencies.

This master's thesis focuses on the subject Management of free capital inside the cryptocurrency market. First, selected cryptocurrencies are briefly described. Subsequently, their historical data are analysed. Finally, based on these findings, an appropriate strategy for the chosen company is formulated.

The world has faced tumultuous times in recent years with the COVID-19 pandemic as well as the Russian invasion of Ukraine causing the stock market to be unusually volatile. During such times investors tend to flee to alternative investment opportunities that are uncorrelated or negatively correlated with the stock market, called safe-haven assets. Traditionally, the most prominent safe-haven asset has been gold but with the rise of cryptocurrencies as a new asset class there has been much speculation if they could act as a safe-haven against the stock market. The leading cryptocurrency Bitcoin is often the main target for such research and has even been called “digital gold”. However, some studies have explored the possibility that the second largest cryptocurrency Ethereum has an even greater potential as a safe-have asset. With the stock market crash in 2020 providing the first “real” test if cryptocurrencies can behave as safe-haven assets a myriad of papers on the topic have been published. However, little research has been done taking on the perspective of a Swedish investor. This thesis aims to fill this research gap by investigating whether the two major cryptocurrencies Bitcoin and Ethereum have acted as safe-havens towards the Swedish stock index OMX30 during the COVID-19 crisis and the Russian invasion of Ukraine. For this purpose, DCC-GARCH analysis was conducted, and the results were compared with gold as benchmark of how a more traditional safe-haven asset has behaved. The findings in this study showed that neither Bitcoin or Ethereum have acted as safe-havens during the COVID-19 crisis or the Russian invasion of Ukraine. The study also finds that gold did not act as a safe-haven for the COVID-19 crisis while it did during the Russian invasion of Ukraine. These findings imply that Bitcoin and Ethereum seem to be unable to act as “digital gold” for Swedish investors in a safe-haven and hedging sense. Instead, these cryptocurrencies have only provided diversification benefits during the recent stock market turmoil.

Blockchain is an interesting technology, with different projects developing every day since it first gained its light back in 2008. More and more research finds blockchain useful in several different sectors. One of the sectors being healthcare, specifically for electronic health records (EHR). EHR contains highly sensitive data which is critical to protect and, just in the year 2019, 41,232,527 records were deemed stolen. Blockchain can provide several benefits when it comes to EHR, such as increased security, availability, and privacy, however, it needs to be done correctly. Due to blockchain being a rather novel technology, there is room for improvement when it comes to integrating blockchain with EHR. In this thesis a framework for EHR in the healthcare sector is proposed, using Ethereum based smart contracts together with decentralized off-chain storage using InterPlanetary File System (IPFS) and strong symmetric encryption. The framework secures the records and provides a scalable solution. Furthermore, a discussion and evaluation regarding several security aspects that the framework excels on as well as what the framework could improve on.

During recent years, attacks on Internet of Things (IoT) devices have grown significantly. Cyber criminals have been using compromised IoT machines to attack others, which include critical internet infrastructure systems. Latest attacks increase the urgency for the information security research community to develop new strategies and tools to safeguard vulnerable devices at any level. Millions of intelligent things are now part of home-based networks that are usually disregarded by solutions platforms, but not by malicious entities.<br>Therefore, the following document presents a comprehensive framework that aims to secure home-based networks, but also corporate and service provider ones. The proposed solution utilizes first-hand information from different actors from different levels to create a decentralized privacy-aware Cyber Threat Information (CTI) sharing network, capable of automate network responses by relying on the secure properties of the blockchain powered by the Ethereum algorithms.

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NFT-teknologin blir mer och mer populär för varje år som går, och under det senaste året hardet mer än dubblerat sitt marknadsvärde från ungefär 22 miljarder dollar till 44 miljarder dollar.Teknologin har applicerats på olika områden och vissa forskare förutspår att teknologinkommer att vara en stor del av Web3 och framtidens internet. Som de flesta andra teknologierfinns det hinder som kan hindra utvecklingen och appliceringen av teknologin. Det är viktigt attidentifiera vilka hinder som teknologin står framför samt få en förståelse för hur dessa hinderfungerar och påverkar.Syftet med denna studie är att undersöka vilka hinder som finns för utvecklingen avNFT-teknologi. Detta görs med en multimetod som kombinerar en intervjustudie och enlitteraturstudie. Intervjustudien genomfördes med fyra semi-strukturerade intervjuer med fyrarespondenter som alla arbetar med NFT. Litteraturstudien undersökte två databaser ochresulterade i 18 artiklar som analyserades. Resultatet från de båda metoderna analyseradessedan med metodtriangulering. Resultatet av studien blev att det identifierades 12 unika hindersom presenteras och analyseras.