Despite the increasing interest in blockchain as a possible solution to replace centralized IoT architectures, previous work failed to provide a direct role for the sensing devices, i.e., direct interaction with the blockchain without additional components. Moreover, few studies focus on permissionless blockchains, even if it is the most secure platform for developing blockchain-based applications. This thesis presents an architecture that considers constrained sensing devices as direct actors on a public blockchain network. A public blockchain network allows the seamless inclusion of several unknown actors, and smart contracts provide a platform to develop complex IoT applications. The research followed an iterative DSR approach; designing, building, and evaluating new IT artifacts using two case studies in the agricultural IoT domain. These cases fostered two exploratory studies that diverged from the main IoT domain; however, they also provide novel contributions to blockchain-based applications. Thus, the novel architecture tackles three problems of current blockchain-based IoT systems i) constrained sensing devices as direct actors on a blockchain system, ii) permissionless blockchain networks and iii) smart contracts as an IoT application platform. Furthermore, the exploratory analyses examine two challenges of blockchain-based applications i) user experience and monetary costs and ii) data sharing and decentralized storage.

Context - Blockchain-based smart contracts have drawn the attention of scientific communities and businesses in recent years. The development of blockchain-based smart contracts is different from the development of conventional software due to the blockchain characteristics such as immutability, trustlessness, being append-only, and being decentralized. Therefore, standard software engineering processes need to be adjusted to address the unique characteristics of blockchain. Objective - This thesis aims to create a structured map of current research on the development of blockchain-based smart contracts, with a focus on identifying and classifying the development phases. Method - To accomplish our objective, we carried out a systematic mapping study on blockchain-based smart contract development. Our search yielded 1257 potentially related studies that were subjected to a selection process. Subsequently, in the final set appeared 41  primary studies. Result - Our main findings after analysis of the data are as follow:  (i) researches mainly contribute to methods and providing tools, (ii) a  large number of workshop papers indicate smart contracts' high acceptance rate, (iii) there is a lack of research on the finalization as a development phase, (iv) there is no common or standard language for specifying smart contracts that are valid regardless of the blockchain platform, (v)  the most common language paradigm for smart contracts specification is imperative/declarative and for smart contracts implementation is declarative, (vi) the research community has put too much effort into the Ethereum blockchain, while it requires putting more attention to other blockchains, and (vii) there is a lack of studies tackling trustworthy oracle and scam challenges. conclusion - These results can benefit the research community to identify trends, constraints, and research gaps. In addition, they share potential directions for future research.

abstract: Smart cities are the next wave of rapid expansion of Internet of Things (IoT). A smart city is a designation given to a city that incorporates information and communication technologies (ICT) to enhance the quality and performance of urban services, such as energy, transportation, healthcare, communications, entertainments, education, e-commerce, businesses, city management, and utilities, to reduce resource consumption, wastage and overall costs. The overarching aim of a smart city is to enhance the quality of living for its residents and businesses, through technology. In a large ecosystem, like a smart city, many organizations and companies collaborate with the smart city government to improve the smart city. These entities may need to store and share critical data with each other. A smart city has several thousands of smart devices and sensors deployed across the city. Storing critical data in a secure and scalable manner is an important issue in a smart city. While current cloud-based services, like Splunk and ELK (Elasticsearch-Logstash-Kibana), offer a centralized view and control over the IT operations of these smart devices, it is still prone to insider attacks, data tampering, and rogue administrator problems. In this thesis, we present an approach using blockchain to recovering critical data from unauthorized modifications. We use extensive simulations based on complex adaptive system theory, for evaluation of our approach. Through mathematical proof we proved that the approach always detects an unauthorized modification of critical data. / Dissertation/Thesis / Masters Thesis Computer Science 2017

<p dir="ltr">Blockchain technology, once the backbone of Bitcoin, has burgeoned into a powerhouse of potential, signaling a revolutionary shift across various sectors, including finance, supply chains, and digital identity. This paradigm shift, which replaces trust in centralized entities with a decentralized ledger of transparency, is rapidly gaining traction among global entities. Despite the promise, blockchain's smart contract evolution has also introduced significant risks, as demonstrated by notorious breaches like the DAO hack. This research offers a dual-focused inquiry into the technological sophistication and social implications of blockchain, particularly smart contracts, assessing both their promise and their perils. It meticulously examines their design, potential vulnerabilities, and recounts sobering lessons from historical breaches.</p><p dir="ltr">To address these concerns, the study presents advanced strategies for vulnerability detection and proactive remedies, recognizing the critical need for security in our digitally convergent economy. In Chapter 3, a novel methodology is employed that uses a comprehensive dataset against advanced detection tools, aiming to address and mitigate vulnerabilities. Chapter 4 provides empirical evidence of the methodology's efficacy, underpinning a critical discussion with real-world applicability and challenges.</p><p dir="ltr">Ultimately, this paper acts as a clarion call for vigilant and innovative strides in blockchain security, emphasizing the technology's vast capabilities against the need for solidified trust. It invites the global research community to join a collaborative effort in addressing the open challenges and fostering advancements to ensure the safe expansion of blockchain technology.</p>

In this paper, we analyse the relation between financial system and financial crises. Our goal is to find how, on the one hand, changes in the financial system affect the prospects for financial crises and, on the other hand, how the occurrence of financial crises shape the core elements of the financial system. We start by defining the financial crisis from three different perspectives. After it, we present the comprehensive history of financial crises that will allow us to continue by drawing some common patterns that are universal. Universal patterns in crises give us the ground for contemplating on some universal policy responses where we again follow different approaches. Taking into account the specifics of modern times and using the young and promising economy based on the blockchain, we are asking the question is this time different?. Analysis of initial development steps in the digital, trustless world gives us the basis for drawing parallels with the reality and the history. Our results suggest that there are many similarities throughout history and between the real and digital world. Instead of providing an exact answer on the question is this time different we conclude that there is a present strong feeling of Deja vu.

Background: Due to the rising popularity of autonomous unmanned vehicles, and the lack of well-defined rules to follow, a solution is needed when the physical space is crowded to a point where it becomes a hazard. Partitioning space discretely is currently done in some cases, allowing vehicles to reserve partitions to operate within. This idea is expanded upon to ultimately propose a blockchain-based solution to the inefficiency of safety margins. Objectives: The main objective was to explore whether a blockchain-based system can be used by vehicles to automatically reserve the volumes of space they need for a limited time. The solution to congestion becomes a method for vehicles to communicate between each other to exchange the remainder of their reservations once they are no longer needed, even while disconnected from the main blockchain network, in exchange for the same currency used to reserve the volumes. Methods: An Ethereum private blockchain network is set up, and a smart contract is developed and deployed onto this blockchain. An emulation program used the smart contract functions to reserve and exchange volumes to evaluate the functionality, several isolated tests evaluated the network performance, and aspects that could not be tested were theoretically analyzed. Results: The system functions as intended, although a level of trust is required during exchanges. There is no risk of two vehicles reserving the same volume at the same time. The results indicate that some performance aspects will be affected by an increasing number of users, although the entire effect can be placed on synchronization time if the network parameters are adjusted. This likely affects the overall efficiency but not as much as it would with the original parameters. Conclusions: The proposed solution is viable to use, although further development is necessary before it is ready for release. The necessity currently is not evident, although projections suggest that this solution, or a similar one, will be necessary in the future.

Since the rise of Bitcoin in 2008, many have speculated about the scope of blockchain technology applications. Prediction markets, i.e. markets in which uncertain outcomes of future events are tradeable, is such an application; blockchain technology may offer several technological attributes that may facilitate prediction market implementations. This study describes and compares the platforms of three organizations that build blockchain prediction market platforms: Augur, Gnosis and Stox. By this, we provide a pertinent overview of current blockchain prediction market applications. Additionally, we conduct interviews with three Swedish blockchain experts clarifying blockchain technology strengths and weaknesses in relation to prediction markets. We identify five factors that are essential for prediction markets to aggregate and reflect information accurately: many actors participating, no actors being prevented from participating, a trustworthy setting function, freedom to create new contracts, and transparency. We conclude that blockchain technology has attributes that facilitate future prediction market implementations in accordance with these requirements. However, blockchain scalability issues pose a key challenge. / Sedan Bitcoins introduktion 2008 har många spekulerat kring omfattningen av blockkedjeteknologins tillämpningsområden. Prediktionsmarknader (eng. prediction markets), d.v.s. marknader i vilka det går att spekulera i osäkra resultat av framtida händelser, är ett sådant tillämpningsområde; blockkedjeteknologi kan tillhandahålla aspekter som främjar implementationer av prediktionsmarknader. Denna artikel beskriver och jämför plattformarna som tillhandahålls av tre organisationer som använder sig av blockkedjeteknologi for att bygga prediktions­marknadsplattformar: Augur, Gnosis och Stox. Genom detta tillhandahåller vi en helhetssyn över nuvarande prediktionsmarknadsplattformar som bygger på blockkedjeteknologi. Dessutom genomför vi intervjuer med tre svenska blockkedjeteknologiexperter, detta för att klargöra blockkedjeteknologis styrkor och svagheter i förhållande till prediktionsmarknader. Vi identifierar fem faktorer som är essentiella för prediktionsmarknaders förmåga att framgångsrikt aggregera och reflektera information: att många aktorer deltar, att inga aktorer är förhindrade från att delta, en tillförlitlig funktion för avgörande av utfall, frihet att skapa nya kontrakt, samt transparens. Vi drar slutsatsen att blockkedjeteknologi, med avseende på dessa faktorer, har egenskaper som förenklar implementationen av prediktionsmarknader. Å andra sidan utgör blockkedjors skalbarhetsproblem en signifikant utmaning.

In this dissertation, I investigate the existing smart contract problems that limit cognitive abilities. I use Taylor's serious expansion, polynomial equation, and fraction-based computations to overcome the limitations of calculations in smart contracts. To prove the hypothesis, I use these mathematical models to compute complex operations of naive Bayes, linear regression, decision trees, and neural network algorithms on Ethereum public test networks. The smart contracts achieve 95\% prediction accuracy compared to traditional programming language models, proving the soundness of the numerical derivations. Many non-real-time applications can use our solution for trusted and secure prediction services.

I extended and adapted the current technology acceptance models and privacy research to the peculiar context of the COVID-19 pandemic to ascertain the effective "power" of IT in fighting such a pandemic. The research models developed for the purpose of this study contain peculiar modifications to the technological-personal-environmental (TPE) framework and privacy calculus model because of the unique technologies implemented and the peculiar pandemic scenario. I developed three studies that investigate the interaction between social, legal, and technical factors that affect the adoption of IoT devices and blockchain systems implemented to fight the spread of COVID-19. Essay 1 systematically reviews existing literature on the analysis of the social, legal, and technical components in addressing phenomena related to IoT architecture and blockchain technology. The employment of a comparable coding method allows finding which of the above components is prominent in relation to the study of IoT and blockchain. Essay 2 develops a technological acceptance model by integrating the TPE framework with new constructs, i.e., regulatory environment, epidemic ecosystem, pre-epidemic ecosystem, perceived social usefulness, and technical characteristics. Essay 3 further explores the interplay between social, legal, and technical factors toward the adoption of smart contracts in the context of the COVID-19 pandemic. Essay 3 integrates the privacy calculus model by introducing new constructs, i.e., technical characteristics, regulatory environment, and perceived social benefits. For both Essays 2 and 3, research surveys were developed and distributed to undergraduate and graduate students in a major university located in the US. The research hypotheses were tested using partial least square modeling.

Banking is considered only one of many industries that could benefit from using blockchain technology. A promising area in blockchain technology is so-called smart contracts, which is automated, decentralized and programmable contract solutions. Smart contracts can control the transfer of currencies or assets between parties under given conditions. The thesis work shows how blockchain technology could be applied to real estate transactions and minimize the need for third party involvement. The purpose of this paper is to provide an overview of the blockchain technology and its possible applications in the real estate market. The focus was on exploring the process of real estate transactions and problems that could be resolved by using smart contracts and blockchain technology. Witha qualitative research approach and a case study analysis, a proposition of a solution was made and discussed with its benefits and drawbacks. The goal was to in the process find the answers for the research questions such as: How can real estate transactions benefit from blockchain technology? What would it cost to store the necessary data on the main chain of Ethereum? How could blockchain technology be used for managing the transaction of the down payment? Even though a collaboration of systems and smart contracts could handle almost every aspect of a real estate transaction, there are still legal boundaries to it being legally enforceable. The blockchain technology could contribute to more efficient and transparent systems compared to traditional centralized solutions.