Dissertations / Theses on the topic 'Blockchains (Databases)'

Blockchain technology is a booming new field in both computer science and economicsand other use cases than cryptocurrencies are on the rise. Permissioned blockchains are oneinstance of the blockchain technique. In a permissioned blockchain the nodes which validatesnew transactions are trusted. Permissioned blockchains and distributed databasesare essentially two different ways for storing data, but how do they compare in terms ofperformance? This thesis compares Hyperledger Fabric to Apache Cassandra in four experimentsto investigate their insert and read latency. The experiments are executed usingDocker on an Azure virtual machine and the studied systems consist of up to 20 logicalnodes. Latency measurements are performed using varying network size and load. Forsmall networks, the insert latency of Cassandra is twice as high as that of Fabric, whereasfor larger networks Fabric has almost twice as high insert latencies as Cassandra. Fabrichas around 40 ms latency for reading data and Cassandra between 150 ms to 250 ms, thusit scales better for reading. The insert latency of different workloads is heavily affected bythe configuration of Fabric and by the Docker overhead for Cassandra. The read latency isnot affected by different workloads for either system.

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.

Cryptocurrencies and blockchains are increasingly used, implemented and adapted for numerous purposes; people and businesses are integrating these technologies into their practices and strategies, creating new political economies and spaces in and of everyday life. This thesis seeks to develop a foundation of geographic theory for the study of spatial production within and surrounding blockchain technologies focusing on acute studies of Bitcoin as cryptocurrency, Ethereum as digital marketplace, and their conditions of possibility as decentralized autonomous organizations. Utilizing concepts from Henri Lefebvre's Production of Space, this thesis situates blockchain technologies within the wider discussion about the political economy of modes of spatial production, dialectical material methods, code/space, and network society through an examination of human and machine relations within their unique and emergent spaces. Combining phenomenological and dialectical material methods with the methodological practice of discourse analysis and systems theory, this thesis explores an understanding of how systemic mechanisms and actant actions driving blockchain technologies are indications of new evolutions in our conceptions of space and place in everyday life of later informational capitalism.

L'Internet des objets (IdO) est en train de transformer l'industrie traditionnelle en une industrie intelligente où les décisions sont prises en fonction des données. L'IdO interconnecte de nombreux objets qui effectuent des tâches complexes. Toutefois, les caractéristiques intrinsèques de l'IdO entraînent plusieurs problèmes, tels que la décentralisation et les problèmes de confidentialité et sécurité. La blockchain est apparue comme une technologie clé pour relever les défis de l'IdO. En raison de ses caractéristiques saillantes telles que la décentralisation, l'immuabilité, et la sécurité, la blockchain a été proposée pour établir la confiance dans plusieurs applications, y compris l'IdO. L'intégration de la blockchain a l'IdO ouvre la porte à de nouvelles possibilités qui améliorent intrinsèquement la fiabilité, la réputation, et la transparence pour toutes les parties concernées, tout en permettant la sécurité. Cependant, les blockchains classiques sont coûteuses en calcul, ont une évolutivité limitée, et nécessitent une bande passante élevée, ce qui les rend inadaptées aux environnements IdO à ressources limitées. L'objectif principal de cette thèse est d'utiliser la blockchain comme un outil clé pour améliorer l'IdO. Pour atteindre notre objectif, nous relevons les défis de la fiabilité des données et de la sécurité de l'IdO en utilisant la blockchain ainsi que de nouvelles technologies émergentes, notamment l'intelligence artificielle
The Internet of Things (IoT) is transforming traditional industry into a smart industry where decisions are made based on data. The IoT interconnects many objects that perform complex tasks. However, the intrinsic characteristics of the IoT lead to several problems, such as decentralization and privacy and security issues. Blockchain has emerged as a key technology to address the challenges of IoT. Due to its salient features such as decentralization, immutability, and security, blockchain has been proposed to establish trust in several applications, including IoT. The integration of blockchain with IoT opens the door to new possibilities that inherently improve trustworthiness, reputation, and transparency for all parties involved, while enabling security. However, conventional blockchains are computationally expensive, have limited scalability, and require high bandwidth, making them unsuitable for resource constrained IoT environments. The main objective of this thesis is to use blockchain as a key tool to improve IoT. To achieve our goal, we address the challenges of data reliability and security in IoT by using blockchain as well as new emerging technologies, including artificial intelligence

Many IT-systems are when created not designed to be flexible and dynamic resulting in old and complex systems hard to maintain. Systems usually build their functionality and capability on the data contained in their databases. The database underlines such system, and when data do not correspond between different and synchronizing systems, it is a troublesome debugging process. This is because systems are complex and the software architecture is not always easy to understand. Due to increasing complexity in systems over time, making systems harder to debug and understand, there is a need for a system that decreases debugging costs. Furthermore, result in better transaction costs. This study proposes a system based on blockchain technology to accomplish this.   An ERP system based on blockchain with encrypted transactions was constructed to determine if the proposed system can contribute in better transaction costs. A case study at multiple IT-companies and comparison to an existing ERP system module validated the system. A successful simulation showed that multiple parts could read and append data to an immutable storage system for one truth of data. By all counts, and with proven results, the constructed blockchain solution based on encrypted transactions for an ERP system can reduce debugging costs.   It is also shown that a centralized database structure where external and internal systems can get one truth of data, decreases transaction costs. However, it is the decision makers in companies that need to be convinced for the constructed system to be implemented. A problem is also when modifications to the object type, then historical transactions cannot be changed in an immutable storage solution. Blockchain is still a new technology, and the knowledge of the technology and the evolution of the system determines if the proposed software architecture will result in better transaction costs.

La conception originale d'Internet n'a pas pris en compte les aspects de sécurité du réseau, l’objectif prioritaire était de faciliter le processus de communication. Par conséquent, de nombreux protocoles de l'infrastructure Internet exposent un ensemble de vulnérabilités. Ces dernières peuvent être exploitées par les attaquants afin de mener un ensemble d’attaques. Les attaques par déni de service distribué (DDoS) représentent une grande menace; DDoS est l'une des attaques les plus dévastatrices causant des dommages collatéraux aux opérateurs de réseau ainsi qu'aux fournisseurs de services Internet. Les réseaux programmables (SDN) ont émergé comme un nouveau paradigme promettant de résoudre les limitations de l’architecture réseau actuelle en découplant le plan de contrôle du plan de données. D'une part, cette séparation permet un meilleur contrôle du réseau et apporte de nouvelles capacités pour mitiger les attaques par DDoS. D'autre part, cette séparation introduit de nouveaux défis en matière de sécurité du plan de contrôle. L’enjeu de cette thèse est double. D'une part, étudier et explorer l’apport du SDN à la sécurité afin de concevoir des solutions efficaces qui vont mitiger plusieurs vecteurs d’attaques. D'autre part, protéger le SDN contre ces attaques. À travers ce travail de recherche, nous contribuons à la mitigation des attaques par déni de service distribué sur deux niveaux (intra et inter-domaine), et nous contribuons au renforcement de la sécurité dans le SDN
The original design of Internet did not take into consideration security aspects of the network; the priority was to facilitate the process of communication. Therefore, many of the protocols that are part of the Internet infrastructure expose a set of vulnerabilities that can be exploited by attackers to carry out a set of attacks. Distributed Denial-of-Service (DDoS) represents a big threat and one of the most devastating and destructive attacks plaguing network operators and Internet service providers (ISPs) in stealthy way. Software defined networks (SDN) is an emerging technology that promises to solve the limitations of the conventional network architecture by decoupling the control plane from the data plane. On one hand, the separation of the control plane from the data plane allows for more control over the network and brings new capabilities to deal with DDoS attacks. On the other hand, this separation introduces new challenges regarding the security of the control plane. This thesis aims to deal with DDoS attacks while protecting the resources of the control plane. In this thesis, we contribute to the mitigation of both intra-domain and inter-domain DDoS attacks, and we contribute to the reinforcement of security aspects in SDN

Blockchain is a new type of shared ledger for distributing and keeping consensus on what constitutes a true state of a system. The implications of the technology, i.e. enabling almost trustless transactions between market participants, is a revolutionary idea, especially to financial markets. The Swedish fund market, being a fragmented and in some cases inefficient system of intermediating actors, is a potential use case for the new technology of blockchain. This report reviews and presents the technology underlying the new blockchain phenomenon, and its potential application to the Swedish fund market with a specific focus on the possible new trust dynamics in such a market. Blockchain could, by removing some of the inter-participant risks, disintermediate the communication between market actors in the Swedish fund market, possibly enabling a cost reduction related to fund unit administration and order handling.
Blockkedje-teknologi är en ny typ av distribuerad databas som med hjälp av kryptologi tillåter ett system av självständiga och icke-tillitande aktörer att gemensamt dela en databas. Implikationerna för teknologin, tillåtandet av näratillitslösa transaktioner mellan marknadsdeltagare, är revolutionära, speciellt finansmarknaderna. Den svenska fondmarknaden, som karaktäriseras av fragmenterade och i vissa fall ineffektiva system, är ett potentiellt appliceringsområde för den nya teknologin. Den här rapporten går över och presenterar den underliggande tecknologin för blockkedjor, och dess potentiella applikation på den svenska fondmarknaden, med ett specifikt fokus på hur appliceringen skulle förändra tillits-förhållandena på marknaden. Det konstateras att blockkedjor skulle b.la. kunna avveckla vissa mellanliggande aktörer på marknaden, och därmed möjliggöra kostnadsbesparingar kopplade till fondadminstration och orderhantering.

У сучасному світі проходить масова електронізація та автоматизація більшості сфер народного господарства, інформаційні технології впроваджуються у найрізноманітніші процеси в управлінні, виробництві, економіці та комерції. Оцифрування ключових сфер діяльності людини вимагає надійних технологій захисту, обробки та зберігання інформації, такі можливості надає технологія blockchain.

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.

In the fields of economics, business and management, how could Digital Transformation (DT) advance value creation and reliably encourage value capture, exchange and distribution? This thesis aim to fill that gap with a novel framework to support policy-makers, countries, cities and businesses address the potential value that can be generated and captured by digitalization combining DT and Internet of Value theoretical perspectives and practical applications of them over concrete issues such as sustainability in cities, as an example. For this, it is proposed to make new contributions related to DT and Internet of Value in two main aspects: to explore DT countries’ mindsets when it relates to their value progress through Digital Ecosystems and to advance with the potential digital value applications through Programmable Economy advantages when it focus on concrete aspect such as sustainability in cities. Both perspectives, although it will be applied on different dimensions and on different purposes, have in common that they are focus on digital and programable value based economy and management and want to explore the best way to maximize and capture the DT potential in terms of value for organizations and society. Thus, first, it will be analysed the importance of knowing clearly the digital ecosystem in which the agents are operating in order to reinforce the value creation by promoting the inclusivity and connectivity of the endpoints involved in it. Secondly, it will be analysed how the digital value can be captured, exchanged and redistributed in a complex issues such as sustainability by deploying concrete digital applications that include human reinforcement aspects to, finally, closing the circle combining both perspectives in a single framework. To achieve these objectives in this thesis, own models are proposed, inspired by other theoretical models already contrasted, and some proven methodologies are used related to Conditional Probability, Forgotten Effects and Fuzzy Sets. As a main conclusion, Digital Transformation has the potential to generate immense value for economy and society. Although currently the capture of the vast majority of it is not guaranteed and its distribution between agents is no clear, new formulas are being explored supported by the Internet of Value. This thesis defends that if agents want to advance value creation and encourage value capture, they should consider to make their own Digital and Programmable Value Based Economy and Management framework through: - Allowing all functional agents work in a Digital Ecosystem embracing new relationships and ways of collaborating pursuing the same purpose. - Deploying Programmable Economy applications advantages, mixing digital's and analogue's world that can be interlinked and programmed by the blockchain allowing monetization and exploring new human and machine alliances. - Adopting strong and inclusive agents’ commitment in order to exploit the advantages that this smart economy system has from a human centric vision, discovering new forms of value, considering that, although tech can be everywhere, value not.

Cette thèse de doctorat se compose de 6 chapitres. Dans le premier chapitre, en guise d'introduction, nous donnons un aperçu des objectifs généraux et des motivations des réseaux décentralisés et permissionless, ainsi que des obstacles auxquels ils sont confrontés. Dans l'introduction, nous évoquons également la solution irrationnelle et illogique, connue sous le nom de « blockchain permissioned », qui a été proposée pour améliorer les performances des réseaux similaires à Bitcoin. Cette question a été détaillée au chapitre 5. Dans le chapitre 2, nous rendons clairs et intelligibles les systèmes que l'idée proposée, « Parallel Committees », est basée sur de tels réseaux. Nous détaillons les fonctionnalités indispensables et les défis essentiels des systèmes de réplication. Ensuite, dans le chapitre 3, nous discutons des limitations de scalabilité et du faible débit des systèmes de réplication qui utilisent des mécanismes de consensus pour traiter les transactions et comment ces problèmes peuvent être améliorés en utilisant des techniques de sharding. Nous décrivons les défis les plus importants dans le sharding des systèmes de réplication distribuée, une approche qui a déjà été mise en œuvre dans plusieurs systèmes de réplication basés sur la blockchain et, bien qu'elle ait montré un potentiel significatif pour améliorer les performances et la scalabilité, les techniques de sharding actuelles ont encore des limitations de scalabilité et des défis de sécurité. Nous expliquons pourquoi la plupart des protocoles de sharding actuels utilisent une approche d'allocation aléatoire pour distribuer les nœuds entre les shards pour des raisons de sécurité. Nous décrivons également comment traiter une transaction dans un système de réplication partitionné basé sur les protocoles de sharding actuels. Nous expliquons comment un « shared-ledger » partagé sur les shards impose des limitations de scalabilité et des défis de sécurité au réseau, et expliquons pourquoi les transactions « cross-shards » ou « inter-shards » sont indésirables et plus coûteuses en raison des problèmes qu'elles causent, y compris « atomicity failure » et les défis de « state transition », ainsi qu'une passe en revue des solutions proposées. Nous passons également en revue certains des travaux récents les plus remarquables qui utilisent des techniques de sharding pour les systèmes de réplication. Cette partie de l'ouvrage a été publiée sous la forme d'un chapitre de livre (peer-reviewed) in « Building Cybersecurity Applications with Blockchain Technology and Smart Contracts » (Springer, 2023). Dans le chapitre 4, nous proposons une nouvelle technique de sharding, « Parallel Committees », prenant en charge à la fois le « processing-sharding » et le « storage/state sharding », pour améliorer la scalabilité et les performances des systèmes de réplication distribués qui utilisent des mécanismes de consensus pour traiter les demandes des clients (client requests). Nous introduisons une approche innovante et originale pour répartir les nœuds entre les shards à l'aide d'un processus de génération de clé publique qui atténue simultanément l'attaque Sybil et sert de mécanisme de preuve de travail (proof-of-work). Notre approche réduit efficacement les transactions « inter-shards » indésirables, qui sont plus complexes et coûteuses à traiter que les transactions « intra-shards ». L'idée proposée a été publiée dans la conférence IEEE BCCA 2023. Nous expliquons ensuite pourquoi nous n'utilisons pas la structure de la blockchain dans l'idée proposée, un sujet abordé en détail au chapitre 5. Cette explication et clarification a été publiée dans le Journal of Software (JSW), Volume 16, Number 3, May 2021. Et dans le dernier chapitre de cette thèse, le chapitre 6, nous résumons les points importants et les conclusions de cette recherche
This PhD thesis consists of 6 Chapters. In the first Chapter, as an introduction, we provide an overview of the general goals and motives of decentralized and permissionless networks, as well as the obstacles they face. In the introduction, we also refer to the irrational and illogical solution, known as "permissioned blockchain" that has been proposed to improve the performance of networks similar to Bitcoin. This matter has been detailed in Chapter 5. In Chapter 2, we make clear and intelligible the systems that the proposed idea, Parallel Committees, is based on such networks. We detail the indispensable features and essential challenges in replication systems. Then in Chapter 3, we discuss in detail the low performance and scalability limitations of replication systems that use consensus mechanisms to process transactions, and how these issues can be improved using the sharding technique. We describe the most important challenges in the sharding of distributed replication systems, an approach that has already been implemented in several blockchain-based replication systems and although it has shown remarkable potential to improve performance and scalability, yet current sharding techniques have several significant scalability and security issues. We explain why most current sharding protocols use a random assignment approach for allocating and distributing nodes between shards due to security reasons. We also detail how a transaction is processed in a sharded replication system, based on current sharding protocols. We describe how a shared-ledger across shards imposes additional scalability limitations and security issues on the network and explain why cross-shard or inter-shard transactions are undesirable and more costly, due to the problems they cause, including atomicity failure and state transition challenges, along with a review of proposed solutions. We also review some of the most considerable recent works that utilize sharding techniques for replication systems. This part of the work has been published as a peer-reviewed book chapter in "Building Cybersecurity Applications with Blockchain Technology and Smart Contracts" (Springer, 2023). In Chapter 4, we propose a novel sharding technique, Parallel Committees, supporting both processing and storage/state sharding, to improve the scalability and performance of distributed replication systems that use a consensus to process clients' requests. We introduce an innovative and novel approach of distributing nodes between shards, using a public key generation process that simultaneously mitigates Sybil attack and serves as a proof-of-work mechanism. Our approach effectively reduces undesirable cross-shard transactions that are more complex and costly to process than intra-shard transactions. The proposed idea has been published as peer-reviewed conference proceedings in the IEEE BCCA 2023. We then explain why we do not make use of a blockchain structure in the proposed idea, an issue that is discussed in great detail in Chapter 5. This clarification has been published in the Journal of Software (JSW), Volume 16, Number 3, May 2021. And, in the final Chapter of this thesis, Chapter 6, we summarize the important points and conclusions of this research

All human interaction can be depicted as exchanges. We exchange trivial information, feelings, assets and more. Valuable exchanges have one thing in common; they all require some degree of trust. In today’s society we rely on institutionalized trust when commencing an exchange of value. Typically, this role is filled by a vast ecosystem consisting of commercial banks, clearinghouses and other third parties. The recent rise of Bitcoin, Ethereum and consequent attention on the underlying technology, blockchain, questions the future of current ecosystem. This report aims at uncovering what blockchain is, what different implementations are currently available and how it would affect today’s ecosystem. It does so through semistructured interviews with actors within the current ecosystem as well as weighing in the views of blockchain evangelists. It highlights five key aspects that are crucial when implementing blockchain technology within the existing banking paradigm. Today’s organized societies require law and order which, to a large extent, is limited within the realm of public blockchain technology. With the insight of society’s infrastructural limitations, this paper argue that the current transaction system of our society favors a permissioned implementation with trusted nodes. Such a system would result in more efficient financial markets and lower costs of transacting. However, this paper acknowledge the virtues and reasons behind the rise of public blockchains. Given recent developments within the field and interesting concepts, the report does not dare to exclude a future of banking relying on public blockchain technology as the underlying database.

La Blockchain è un deposito di dati distribuito costituito da una lista di record (in continua crescita) resistente a modifiche e revisioni, anche da parte degli operatori dei nodi (computer) su cui risiede. I dati sono sicuri anche in presenza di partecipanti non affidabili o disonesti alla rete. Una copia totale o parziale della blockchain è memorizzata su tutti i nodi. I record contenuti sono di due tipi: le transazioni, che sono i dati veri e propri, e i blocchi, che sono la registrazione di quanto ed in quale ordine le transazioni sono state inserite in modo indelebile nel database. Le transazioni sono create dai partecipanti alla rete nelle loro operazioni (per esempio, trasferimento di valuta ad un altro utente), mentre i blocchi sono generati da partecipanti speciali, i cosiddetti “miners”, che utilizzano software e a volte hardware specializzato per creare i blocchi. L’attività dei miners viene ricompensata con l’assegnazione di “qualcosa”, nel caso della rete Bitcoin di un certo numero di unità di valuta. Spesso negli esempi si fa riferimento alla Blockchain di Bitcoin perché è la catena di blocchi implementata per prima, e l'unica ad avere una dimensione consistente. Le transazioni, una volta create, vengono distribuite sui nodi con un protocollo del tipo “best effort”. La validità di una transazione viene verificata attraverso il consenso dei nodi della rete sulla base di una serie di parametri, che variano secondo l’implementazione specifica dell’architettura. Una volta verificata come valida, la transazione viene inserita nel primo blocco libero disponibile. Per evitare che ci sia una duplicazione delle informazioni l’architettura prevede un sistema di time stamping, che non richiede un server centralizzato.

This thesis aims to explore the compliance of blockchain technology and the GDPR. The GDPR was implemented for the EU member states in May 2018 with the purpose of harmonizing data protection regulation. However, the regulation is based on the notion that data is stored and processed in a centralized system. This causes an issue when it comes to distributed networks, and in particular with the distributed ledger technology (DLT), the underlying technology of blockchain. For this thesis, a literature review has been conducted to investigate the problems of GDPR compliance for blockchain projects, and what technical solutions exist to make a blockchain solution more GDPR compliant. In addition, interviews have been conducted to investigate the technical and legal perspectives on the current and future situations of regulation and technology. Compatibility problems mainly concern the immutability and transparency of a blockchain and examples of technical solutions that handle those problems can be found in the literature. Nevertheless, none of the discussed solutions are yet to guarantee full GDPR compliance. The technical and legal perspectives share ideas of the main compliance issues. However, differences such as interpretation of technical details can be identified, indicating problems to arise when regulating blockchains in the future. Further interdisciplinary work on guidelines for the GDPR is necessary for blockchain projects to be successful in complying with the regulation as well as to strengthen the technology neutrality of the GDPR.

The final thesis deals with the and design of the information system in the form of a conceptual design in the company Imperial invest funds s.r.o., the aim of the thesis is the efficiency of the work in the company, reducing the load of human resources, automating the processes and increasing the integrity of the IS in the functioning of the company. The main objective is to analyze existing workflows and utilization of existing information systems, and to eliminate these drawbacks or replace them with a new solution on the basis of a bottleneck analysis.

A research article submitted to the Faculty of Commerce, Law and Management, University of the Witwatersrand, in partial fulfilment of the requirements for the degree of Master of Business Administration Johannesburg, 2018
Blockchain technology is a foundational technology with various use cases that can significantly impact the manner in which banking is carried out in South Africa. The following paper seeks to put together a framework for understanding the potential effect of blockchain technology on the South African banking environment, with a specific focus on how blockchain technology will impact the South African banking environment (i.e. the applications and use cases) and when this impact will take place. A qualitative approach to addressing the problem statement was adopted, specifically in the form of focus interviews and strategic discussions with subject matter experts in both the blockchain and South African banking environment. Findings indicate that there are number of blockchain applications that can impact the South African banking environment namely, Private Digital Ledgers, Smart Contracts and Tokens/ Cryptocurrencies. Further to this, research indicates that the former is most likely in the short term, while the latter two applications are subject to a high-level stakeholder coordination, a high level of effort in educating the end customer and a high level of friction from existing systems and process, and will therefore only realise mass adoption in the long-term. As a result, this research contributes to providing an initial view of which applications are most likely to be adopted by South African banks and can form the foundation for further research in this area.
E.K. 2019

Newly emerging cryptocurrencies and blockchain technology provide a challenging research problem for human geographers. Bitcoin, the first widely implemented cryptocurrency and example of a blockchain architecture, seemingly separates itself from the existing territorial boundedness of nation state currencies via a digital process of algorithmic decentralisation. Proponents declare that utilisation of cryptography to advance blockchain transactions will disrupt the modern centralised structures by which capitalist economies are currently organised: corporations, commercial banks, and central banks. I contest this perspective. The core argument of this thesis is that blockchains must be understood as a spatial problem where power is unevenly distributed across their networks. Secondly, and building upon this principle, it is proposed that algorithmic decentralisation is inherently a contradictory concept by highlighting a number of distinctive points across Bitcoin’s architecture where forms of centralised control are competed for. Thirdly, the thesis describes how online communities, start-up companies, and existing financial institutions exercise power from these many centres by paying close attention to the political ideologies and practices that combine to form a unique technoculture. This research analyses these sociotechnical dynamics, systems, and conditions to make intelligible the political, cultural, and economic geographies of blockchains. In doing so the thesis builds on existing literatures and empirical research pertaining to money/space and code/space to critically evaluate the postulation of blockchain decentralisation. An actor-network inspired ‘follow the thing’ methodology enables the thesis to navigate and trace some of the primary connections between diverse sociotechnical actors that create blockchain economies. The method of ‘following’ extends into an examination of the Bitcoin source code, online forums, and social media activity so as to develop a critical understanding of blockchain’s cultural economic geographies. By tracing both the humans and non-humans of Bitcoin’s infrastructure the way in which transactions are materially tied together through space is outlined. Additionally, the technique of snowball sampling was used to conduct participant observation and semi-structured interviews in the burgeoning Bitcoin/blockchain ecosystem of Silicon Valley, supported by an investigation of key entrepreneurial spaces, such as start-up companies and meet-up groups, in London and New York City. These methods help develop an analytical framework that demonstrates how the technical parameters of blockchains—block size, private key control, mining operations—are altered by people in varied cultural settings and thus practise and shape blockchains in competing ways. The analysis of empirical data frames different ‘spaces’ as strategic passage points through which various practices are increasingly funnelled (Callon, 1986). Examining these bottlenecks from a cultural economic geography perspective, this thesis demonstrates how the codified architectures of blockchains are (re)centred on a number of levels: governance mechanisms that organise their programmers; materialities of infrastructure that execute their code; bureaucratic business models built by start-up companies to profit from their transaction structures, and; the embeddedness of technical knowledge within industrial agglomerations. These empirical observations provide the foundation for a critique of blockchain ‘solutionism’ that envisions distributed algorithmic software as the harbinger of more stable and democratic economies by transferring governance to the mathematical constraints of computer code. Subsequent analysis contributes to spatial theory by outlining a cultural economic geography of Bitcoin and copycat blockchain projects where a hybrid form of human-machine governance shapes their algorithmic structures. While blockchain economies transform the relationships between money, code, and space, the study and analysis of key points where money/code/space is produced, contested, and monitored shows how algorithmic decentralisation is predicated on centralised actors, practices, and forces.

Blockchain technology elegantly provides a spectrum of desirable semantic properties, including immutability, authenticity, verifiability, and data integrity. In recent years, implementing blockchains on relational database platforms has been advocated as a synergistic enterprise that leverages their efficient data processing capabilities. Therefore, in this work, we study Credereum, a public-domain software that layers blockchain semantics on native PostgreSQL. Specifically, Credereum is intended for delivering cryptographically verifiable consensus and provenance in a permissioned centralized setting, using an Ethereum smart contract as an immutable trusted storage repository. Our motivation for choosing Credereum is that it is among the few public-domain permissioned blockchain systems developed on an RDBMS platform. However, while studying Credereum, we encountered two major issues – the first related to security, with a potential for malicious server activity in block Merkle formation, and the other with regard to degraded transaction throughput. We address both these issues in our work, as described in the following. With regard to security, Credereum summarizes the modifications made at transaction-level and block-level by constructing Merkle trees, namely, Transaction Merkle Tree (TMT) and Block Merkle Tree (BMT). However, the BMT details are hidden from the clients, and therefore the server can maliciously include extra rows, leading to ledger invalidity. To tackle this loophole, we propose SecCred, which displays the block Merkle details for clients to verify in SHA-256 hash forms. Importantly, these changes retain Credereum’s native blockchain properties, and do not incur perceptible processing overheads. Turning to performance, our analysis shows that the Credereum blockchain semantics are obtained with enormous cost in performance – specifically, orders-of-magnitude degradation in transaction throughput as compared to native PostgreSQL. We carefully investigate the sources of this massive deterioration, and propose an initial set of simple but potent programming and algorithmic changes to the Credereum software that help retrieve an order-of-magnitude of the lost performance. These modifications are primarily with respect to the procedures for string matching and TMT formation. Again, our modified versions, called ProgCred, PerfCredA and PerfCredB, are implemented so as to preserve Credereum’s blockchain semantics.

Кваліфікаційна робота присвячена створенню прототипу системи забезпечення достовірності документів із тривалим терміном зберігання в електронному архіві, який використовує технологію Blockchain. Описані особливості електронного архіву, проведено аналіз способів зберігання документів в архіві та обґрунтовано технології, які використовуються для реалізації обраного способу. Також досліджено існуючі способи забезпечення достовірності документів та існуючі реалізації електронного архіву на основі технології Blockchain. Обґрунтовано вибір технологій, наведено опис API системи. Реалізовано прототип системи електронного архіву, що використовує технологію Blockchain, для вирішення проблеми автентичності документів тривалого терміну зберігання.
Thesis deals with the creation of a prototype of a system for ensuring the authenticity of documents with a long shelf life in an electronic archive, which uses Blockchain technology. Features of the electronic archive are described, the analysis of ways of storage of documents in archive is carried out and the technologies which are used for realization of the chosen way are substantiated. Existing methods of ensuring the authenticity of documents and existing implementations of electronic archives based on Blockchain technology are also investigated. The choice of technologies is substantiated, the description of API of the system is given. A prototype of an electronic archive system using Blockchain technology has been implemented to solve the problem of authenticity of long-term storage documents.
Вступ ...7 1 Аналіз досліджуваної області ...8 1.1 Зберігання документів в архіві в паперовому вигляді ...8 1.2 ЕА .... 8 1.2.1 Види ЕА ...9 1.2.2 Основні проблеми ЕА ...9 1.3 Способи забезпечення достовірності документів ...10 1.3.1 ЕП ...10 1.3.2 Blockchain...12 2 Проектна частина ...16 2.1 Існуючі реалізації ЕА на основі технології Blockchain ...16 2.1.1 BlockSign ...16 2.1.2 Ethereum ...17 2.2 Загальний опис розроблюваної системи ...19 2.3 Обґрунтування вибору технологій ...22 2.4 Опис API системи...25 3 Програмна реалізація системи ...28 3.1 API додатка основної бізнес-логіки ...28 3.2 API додатка для зберігання документів з підвищеною захищеністю ... 33 3.3 API додатка для кожного вузла в мережі Blockchain ...37 4 Безпека життєдіяльності, основи охорони праці ...45 4.1 Навчання працюючих і інструктажі з охорони праці ...45 4.2 Заходи захисту від випромінювань оптичного діапазону ...47 Висновки ... 50 Перелік використаних джерел ...51

In service-oriented architecture, services can communicate and share data among themselves. This thesis presents a solution that allows detecting several types of data leakages made by authorized insiders to unauthorized services. My solution provides role-based and attribute-based access control for data so that each service can access only those data subsets for which the service is authorized, considering a context and service’s attributes such as security level of the web browser and trust level of service. My approach provides data protection in transit and at rest for both centralized and peer-to-peer service architectures. The methodology ensures confidentiality and integrity of data, including data stored in untrusted cloud. In addition to protecting data against malicious or curious cloud or database administrators, the capability of running a search through encrypted data, using SQL queries, and building analytics over encrypted data is supported. My solution is implemented in the “WAXEDPRUNE” (Web-based Access to Encrypted Data Processing in Untrusted Environments) project, funded by Northrop Grumman Cybersecurity Research Consortium. WAXEDPRUNE methodology is illustrated in this thesis for two use cases, including a Hospital Information System with secure storage and exchange of Electronic Health Records and a Vehicle-to-Everything communication system with secure exchange of vehicle’s and drivers’ data, as well as data on road events and road hazards.

To help with investigating data leakage incidents in service-oriented architecture, integrity of provenance data needs to be guaranteed. For that purpose, I integrate WAXEDPRUNE with IBM Hyperledger Fabric blockchain network, so that every data access, transfer or update is recorded in a public blockchain ledger, is non-repudiatable and can be verified at any time in the future. The work on this project, called “Blockhub,” is in progress.