The real estate sector has a large impact on the economy and a significant impact on financialmarket stability. Several unique features characterize the real estate market assets; these arestable cash flow, a stable demand, and low volatility, contributing to the underlying value.However, the industry is considered illiquid due to a lack of transparency, informationasymmetry, and difficulty in quickly executing a trade. Tokenization, smart contracts, anddigital identities are some of the applications of blockchain, which are regarded to be onerevolutionary technology that has the potential to change the real estate market. However, it isnot clear how these technologies would impact real estate transaction processes in the future.Previous research has looked at the blockchain as a financial tool and how it connects to realestate as a legal instrument and a transaction market application to improve transparency andliquidity. However, the previous research has not considered the main risks and challenges witha blockchain adoption in the Swedish residential real estate market. Therefore, this thesis looksat how blockchain technology can be used in the residential real estate sector. The dissertationhas been answered through a structured qualitative study with an inductive approach. Theempirics has been gathered through a literature study, semi-structured interviews, and adocument analysis.The results illustrate that blockchain can be useful in residential real estate transactionprocedures through tokenization, storing ledger, and digital identities. Through our analysis,we could conclude that to adopt blockchain, the industry must take small steps in the directionthat the digital evolution wishes to go. It is not possible to drastically implement blockchain inthe residential real estate market, rather a successive transaction with the help of innovationsand new regulations from the authorities.The ability to store and validate data has been a primary rationale for using the technology asthe industry adjusts to conventional analog business processes that are becoming increasinglydigital. Despite that many view blockchain as a technology that quickly disrupts real estatetransaction processes, we conclude that blockchain innovation instead progressesincrementally due to many challenges and risks associated with the technology and theindustry’s conservative nature. The research contributes to a better understanding of blockchaintechnology and its possibilities and challenges in the real estate industry. / Fastighetssektorn är en sektor som har stor inverkan på ekonomisk tillväxt och betydandeinverkan på finansmarknadens stabilitet. Bostadsfastigheter har flera unika egenskaper somkännetecknar dessa tillgångar. Några av dessa är det stabila kassaflödet, en stabil efterfråganoch en låg volatilitet, vilket bidrar till det underliggande värdet. Branschen anses dock varaillikvid på grund av bristande transparens i sina transaktioner, informationsasymmetri ochsvårigheter att genomföra en snabb transaktion. Tokenisering, smarta kontrakt och digitalaidentiteter är några av tillämpningarna för blockchain, som anses vara en revolutionerandeteknik som har potential att förändra fastighetsmarknaden, men det är inte klart hur dessateknologier skulle påverka processer för fastighetstransaktioner i framtiden.Tidigare forskning har tittat på blockkedjan som ett finansiellt verktyg och hur den hjälperfastighetsmarknaden som ett juridiskt instrument, såväl som transaktionsmarknadsapplikationför att förbättra transparens och likviditet. Den tidigare forskningen har dock inte övervägtriskerna och utmaningarna med en blockchain-adoption på den svenskabostadsfastighetsmarknaden. Därför är syftet med denna uppsats att undersöka hurblockkedjeteknologi kan användas inom bostadsfastighetssektorn. Avhandlingen har besvaratsgenom en strukturerad kvalitativ studie, med ett induktivt förhållningssätt. Empirin har samlatsin genom en litteraturstudie, semistrukturerade intervjuer och en dokumentanalys.Resultaten illustrerar att blockchain kan användas i bostadsfastighetstransaktioner genomtokenisering, lagring av reskontra och digitala identiteter. Genom vår analys kunde vi draslutsatsen att en adoption av blockchain måste ta små steg i den riktning som den digitalautvecklingen vill gå. Det är inte möjligt att drastiskt implementera blockchain påbostadsfastighetsmarknaden, snarare en successiv övergång med hjälp av nya innovationer ochnya regleringar från myndigheterna.Möjligheten att lagra och validera data har varit en primär motivering för att använda teknikennär branschen anpassar sig till det faktum att konventionella analoga affärsprocesser blir alltmer digitala. Trots att många ser blockchain som en teknik som revolutionerarfastighetstransaktionsprocesser, drar vi slutsatsen att blockchain-innovationen snarare börimplementeras stegvis. Detta beror på många utmaningar och risker förknippade med tekniken,samt på grund av branschens konservativa karaktär. Forskningen bidrar till en bättre förståelseav blockkedjeteknologin, samt dess möjligheter och utmaningar inom fastighetsbranschen.

The goal of this study is to identify the current application areas and some possible application areas for blockchain; blockchain is a distributed database that is currently most known for being the technology used for storing transaction information of digital currencies such as the Bitcoin. Through a literature review and interviews with domain experts, we identified some current application areas for blockchain, that is, money transactions, decentralized data and privacy protection, and decentralized autonomous organizations (DAO). Within the area of decentralized data and privacy protection, we further identified the two sub-areas of smart contracts and secure identities. In addition, we identified some possible application areas by conducting a second literature review. Some of these application areas are: storing mind files and human intelligence, on-line voting, supply chain management, stock trading, Internet of Things (IoT), and banking. The contribution of this study can be used for further studies through each of the above application areas in order to identify possible advantages and disadvantages.

近年來區塊鏈技術及其相關應用成為熱門焦點，區塊鏈最大的特色包含去中心化以及匿名性等特性，然而在這樣的分散式網路中我們很難判斷對方是否值得信賴，在數位憑證中我們透過可信賴第三方擔任憑證中心為用戶簽發金鑰憑證以此建立用戶之間的信賴關係，但在區塊鏈此種分散式網路中找到一個可信賴第三方實屬不易，並且可能會與區塊鏈去中心化之特性背道而馳，因此本研究參考PGP信任網與小世界理論的概念，建立一套可適用於分散式環境中基於聲譽的信任度評估機制，並將此機制結合智能合約實現一個信任度評估機制購物平台，目的希望用戶與陌生人交易前，可透過此機制計算出信任度，提供用戶做為參考，幫助用戶更容易判斷陌生人是否可信，以降低受騙風險。 / In recent years, the blockchain technology and its relevant applications become hot spots. The greatest feature of the blockchain is the decentralization. Nonetheless, it is difficult for us to judge whether the other person get involved in the decentralized network is credible. Furthermore, it is difficult to find a reliable third party in such a point-to-point network. Consequently, this paper refers to the PGP web of trust and the small world problem to establish a set of reputation-based trust evaluation mechanism for decentralized environments, we combine this mechanism with a smart contract to achieve a trust evaluation mechanism shopping platform, It is expected that achievements of the paper can facilitate people’s judgment regarding the reliability of strangers and reduce the risks of being deceived.

區塊鏈有著不可否認性、可追溯性以及共識性等特點，所有的交易內容都會完整的被記錄在區塊鏈上，基於上述幾項特性，我們利用區塊鏈來記錄公開資訊，將私密資料經由分散式秘密共享後再加密存放於智能合約中。其中，智能合約是一個能將交易狀態和交易狀態內嵌於區塊鏈上的應用，透過智能合約作為媒介，我們能夠將加密後的私密資料完整的存放於區塊鏈上，最後經由區塊鏈網路上的節點驗證後，達到資料正確性驗證的目的。 本研究分析現有的電子投票以及電子投標等應用的系統架構後，發現兩者皆存在著可信賴的第三方進行開票及開標的角色，且驗證流程繁瑣，無法提供一個便利性的投票與投標流程。此外，上述兩種應用皆須滿足機密性、不可否認性、匿名性以及可驗證性等安全性質，若能結合區塊鏈與智能合約於上述應用中，將可提升資料的可驗證性以及降低成本的負擔，對參與應用的人而言也能達到公開透明的需求。 因此，本文提出一個分散式架構下的電子投票與投標機制，結合區塊鏈以及智能合約的優點與技術，讓所有參與投票的選民、投標的廠商共同參與驗證與計算，並加強參與者的匿名性、資料傳輸的隱私性、開票與開標階段資料的可信賴性以及可驗證性。 / With the rise of blockchain technology, the core concept of decentralization has gradually drawn attention. In this context, the main objective of this study is to realize more convenient and secure electronic applications with the use of blockchain technology. This research is aimed to design a distributed e-voting and e-bidding system. The core idea is to combine the blockchain technology with secret sharing scheme and homomorphic encryption in order to realize the distributed e-voting and e-bidding application without a trusted third party. The system allows voters to participate in opening phase. It provides a public and transparent process while protecting the anonymity of voter’s and vendor’s identity, the privacy of data transmission and verifiability of data during the opening phase.

The challenge of implementing and executing a legal contract in a machine has been gaining significant interest recently with the advent of blockchain, smart contracts, LegalTech and IoT technologies. Popular software engineering methods, including agile ones, are unsuitable for such outcome-critical software. Instead, formal specifications are crucial for implementing smart contracts to ensure they capture the intentions of stakeholders, also that their execution is compliant with the terms and conditions of the original natural-language legal contract. This thesis concerns supporting the semi-automatic generation of formal specifications of legal contracts written in Natural Language (NL). The main contribution is a framework, named Contratto, where the transformation process from NL to a formal specification is subdivided into 5 steps: (1) identification of ambiguous terms in the contract and manual disambiguation; (2) structural and semantic annotation of the legal contract; (3) discovery of relationships among the concepts identified in step (2); (4) formalization of the terms used in the NL text into a domain model; (5) generation of formal expressions that describe what should be implemented by programmers in a smart contract. A systematic literature review on the main topic of the thesis was performed to support the definition of the framework. Requirements were derived from standard business contracts for a preliminary implementation of tools that support the transformation process, particularly concerning step (2). A prototype environment was proposed to semi-automate the transformation process although significant manual intervention is required. The preliminary evaluation confirms that the annotation tool can perform the annotation as well as human annotators, albeit novice ones.

The adoption of blockchain technology for cross-border payments is not an easy task.However this qualitative study further investigates the connotations associated with adoptionof blockchain in cross-border financial transactions within Swedish financial institutions suchas banks, fintech, and credit management service companies. To answer this question, weinterviewed six participants that work in a credit management company, an open bankingcompany, and a digital mortgage service company using semi-structured interviews. Datacollection was done using this method because the purpose of this research work is to identifypeople's insights and experiences based on their real-life experiences. Data were analyzedusing thematic analysis. Our results showed that the impact of adoption of blockchain incross-border payment transactions in terms of technical implementation challenges,customers' use cases and pilot programs, compliance and security enhancements, industrycollaboration and knowledge sharing, legacy systems integration and interoperability, and keydrivers beyond adoption. In addition, the study findings were compared with the determinantsand influence factors of the model through the lens of the DOI. The implications of this studycould used to help financial institutions' focus on blockchain adoption in cross-borderpayment transactions. As a whole, this study contributes to the idea that financial institutionsshould develop an accurate strategy, as well as guidelines that can assist them in leveragingblockchain technology for cross-border payments, enhancing their services, and fosteringsustainable growth in cross-border digital markets.

This thesis investigates how Large Language Models can be used to repair Solidity Smart Contracts automatically through the main contribution of this thesis, the Transformative Repair Tool. The Transformative Repair Tool achieves similar results to current state-of-the-art tools on the Smartbugs Curated Dataset and is the first published tool that uses Large Language Models to repair Solidity Smart Contracts. Moreover, the thesis explores different prompt strategies to repair Smart Contracts and assess their performance. / Detta masterexamensarbete undersöker hur stora språkmodeller kan användas för att automatisk laga solidity smarta kontrakt genom verktyget Transformative Repair Tool, som är detta masterexamensarbete huvudsakliga bidrag. Transformative Repair Tool presterar liknande som dagens bästa verktyg inom automatisk lagning av smarta kontrakt på Smartbugs Curated datasettet och är det första publicerade verktyget som just använder stora språkmodeller för att reparera solidity smarta kontrakt. Dessutom så utforskar denna rapport olika textprompts och dess prestanda för att laga smarta kontrakt

This thesis proposes an Ecosystem perspective for the engineering of SoS and CPS and illustrates the impact of this perspective in three areas of contribution category First, from a conceptual and Systems Engineering perspective, a conceptual framework including the Ecosystems of System Unified Language Modeling (EoS-UML) profile, a set of Ecosystem Ensemble Diagrams, the Arms :Length Trust Model and the Cyber Physical Threat Model are provided. Second, having established this conceptual view of the ecosystem, we recognize unique role of the cryptographic credentials within it, towards enabling the ecosystem long-term value proposition and acting as a value transfer agent, implementing careful balance of properties meet stakeholder needs. Third, we propose that the ecosystem computers can be used as a distributed compute engine to run Collaborative Algorithms. To demonstrate, we define access control scheme, risk-balanced Cellular Access Control (rbCAC). The rbCAC algorithm defines access control within a cyber-physical environment in a manner which balances cost, risk, and net utility in a multi-authority setting. rbCAC is demonstrated it in an Air Travel and Border Services scenario. Other domains are also discussed included air traffic control threat prevention from drone identity attacks in protected airspaces. These contributions offer significant material for future development, ongoing credential and ecosystem design, including dynamic perimeters and continuous-time sampling, intelligent and self optimizing ecosystems, runtime collaborative platform design contracts and constraints, and analysis of APT attacks to SCADA systems using ecosystem approaches.

The ideas and techniques of cryptography and decentralized storage have seen tremendous growth in many industries, as they have been adopted to improve activities in the organization. That called Blockchain technology, it provides an effective transparency solution. Generally, Blockchain has been used for digital currency or cryptocurrency since its inception. One of the best-known Blockchain protocols is Ethereum, which has invented the smart contract to enable Blockchain’s ability to execute a condition, rather than simply acting as storage. Applications that adopt this technology are called ‘Dapps’ or ‘decentralized applications’. However, there are ongoing arguments about synchronization associated with the system. System synchronization is currently extremely important for applications, because the waiting time for a transaction to be verified can cause dissatisfaction in the user experience. Several studies have revealed that privacy leakage occurs, even though the Blockchain provides a degree of security, as a result of the traditional transaction, which requires approval through an intermediate institution. For instance, a bank needs to process transactions via many constitution parties before receiving the final confirmation, which requires the user to wait for a considerable amount of time. This thesis describes the challenge of transaction synchronization between the user and smart contract, as well as the matter of a privacy strategy for the system and compliance. To approach these two challenges, the first task separates different events and evaluates the results compared to an alternative solution. This is done by testing the smart contract to find the best gas price result, which varies over time. In the Ethereum protocol, gas price is one of the best ways to decrease the transaction time to meet user expectations. The gas price is affected by the code structure and the network. In the smart contract, testing is run based on two cases, and solves platform issues such as runners and user experience and reduces costs. It has also been found that collecting the fee before participating in an auction can prevent the problem of runners. The second case aims to prove that freezing the amount of a bid is the best way to increase the user’s experience, and to achieve the better experience of an online auction. The second challenge mainly focuses on the privacy strategy and risk management for the platform, which involves identifying possible solutions for all risk situations, as well as detecting, forecasting and preventing them. Providing strategies, such as securing the smart contract structure, increasing the encryption method in the database, designing a term sheet and agreement, and authorization, help to prevent system vulnerabilities. Therefore, this research aims to improve and investigate an online auction platform by using a Blockchain smart contract to provide evocative user experiences. / Idéer och tekniker för kryptografi och decentraliserad lagring har haft en enorm tillväxt i många branscher, eftersom de har antagits för att förbättra verksamheten i organisationen. Den som kallas Blockchain-tekniken ger den en effektiv transparenslösning. Generellt har Blockchain använts för digital valuta eller cryptocurrency sedan starten. Ett av de mest kända Blockchainprotokollen är Ethereum, som har uppfunnit det smarta kontraktet för att möjliggöra Blockchains förmåga att utföra ett villkor, snarare än att bara fungera som lagring. Applikationer som använder denna teknik kallas 'Dapps' eller 'decentraliserade applikationer'. Det finns emellertid pågående argument om synkronisering associerad med systemet. Systemsynkronisering är för närvarande oerhört viktigt för applikationer, eftersom väntetiden för att en transaktion ska verifieras kan orsaka missnöje i användarupplevelsen. Flera studier har visat att sekretessläckage inträffar, även om Blockchain ger en viss säkerhet, till följd av den traditionella transaktionen, som kräver godkännande genom en mellaninstitution. Till exempel måste en bank bearbeta transaktioner via många konstitutionspartier innan den får den slutliga bekräftelsen, vilket kräver att användaren väntar en betydande tid. Den här avhandlingen beskriver utmaningen med transaktionssynkronisering mellan användaren och smart kontrakt, samt frågan om en sekretessstrategi för systemet och efterlevnad. För att närma sig dessa två utmaningar separerar den första uppgiften olika händelser och utvärderar resultaten jämfört med en alternativ lösning. Detta görs genom att testa det smarta kontraktet för att hitta det bästa gasprisresultatet, som varierar över tiden. I Ethereum-protokollet är gaspriset ett av de bästa sätten att minska transaktionstiden för att möta användarens förväntningar. Gaspriset påverkas av kodstrukturen och nätverket. I det smarta kontraktet körs test baserat på två fall och löser plattformsproblem som löpare och användarupplevelse och minskar kostnaderna. Det har också visat sig att insamlingen av avgiften innan du deltar i en auktion kan förhindra löparproblemet. Det andra fallet syftar till att bevisa att frysning av budbeloppet är det bästa sättet att öka användarens upplevelse och att uppnå en bättre upplevelse av en online auktion. Den andra utmaningen fokuserar huvudsakligen på sekretessstrategin och riskhanteringen för plattformen, som innebär att identifiera möjliga lösningar för alla risksituationer, samt att upptäcka, förutse och förhindra dem. Tillhandahållande av strategier, som att säkra den smarta kontraktsstrukturen, öka krypteringsmetoden i databasen, utforma ett termblad och avtal och godkännande, hjälper till att förhindra systemets sårbarheter. Därför syftar denna forskning till att förbättra och undersöka en online-auktionsplattform genom att använda ett smart avtal med Blockchain för att ge upplevande användarupplevelser.

<div>Graph-structured data is pervasive. Modeling large-scale network-structured datasets require graph processing and management systems such as graph databases. Further, the analysis of graph-structured data often necessitates bulk downloads/uploads from/to the cloud or edge nodes. Unfortunately, experience has shown that malicious actors can compromise the confidentiality of highly-sensitive data stored in the cloud or shared nodes, even in an encrypted form. For particular use cases —multi-modal knowledge graphs, electronic health records, finance— network-structured datasets can be highly sensitive and require auditability, authentication, integrity protection, and privacy-preserving computation in a controlled and trusted environment, i.e., the traditional cloud computation is not suitable for these use cases. Similarly, many modern applications utilize a "shared, replicated database" approach to provide accountability and traceability. Those applications often suffer from significant privacy issues because every node in the network can access a copy of relevant contract code and data to guarantee the integrity of transactions and reach consensus, even in the presence of malicious actors.</div><div><br></div><div>This dissertation proposes breaking from the traditional cloud computation model, and instead ship certified pre-approved trusted code closer to the data to protect graph-structured data confidentiality. Further, our technique runs in a controlled environment in a trusted data owner node and provides proof of correct code execution. This computation can be audited in the future and provides the building block to automate a variety of real use cases that require preserving data ownership. This project utilizes trusted execution environments (TEEs) but does not rely solely on TEE's architecture to provide privacy for data and code. We thoughtfully examine the drawbacks of using trusted execution environments in cloud environments. Similarly, we analyze the privacy challenges exposed by the use of blockchain technologies to provide accountability and traceability.</div><div><br></div><div>First, we propose AGAPECert, an Auditable, Generalized, Automated, Privacy-Enabling, Certification framework capable of performing auditable computation on private graph-structured data and reporting real-time aggregate certification status without disclosing underlying private graph-structured data. AGAPECert utilizes a novel mix of trusted execution environments, blockchain technologies, and a real-time graph-based API standard to provide automated, oblivious, and auditable certification. This dissertation includes the invention of two core concepts that provide accountability, data provenance, and automation for the certification process: Oblivious Smart Contracts and Private Automated Certifications. Second, we contribute an auditable and integrity-preserving graph processing model called AuditGraph.io. AuditGraph.io utilizes a unique block-based layout and a multi-modal knowledge graph, potentially improving access locality, encryption, and integrity of highly-sensitive graph-structured data. Third, we contribute a unique data store and compute engine that facilitates the analysis and presentation of graph-structured data, i.e., TruenoDB. TruenoDB offers better throughput than the state-of-the-art. Finally, this dissertation proposes integrity-preserving streaming frameworks at the edge of the network with a personalized graph-based object lookup.</div>