Although cryptography based remote voting protocols have been researched since 1981, most of the previous protocols [9], [5], [13] assume the existence of public bul- letins or, in other words, a publicly readable, tamper-proof, append-only log. As blockchain or distributed ledger technology (DLT) offers properties like irreversibil- ity, transparency and decentralization, it is suitable for realization of public bulletin board for the voting system. We see a gap in the research of blockchain based voting systems because there either exists work on just the protocol aspect of the voting system or the performance aspect of the blockchain. As blockchain is a general purpose tool, we believe that there lies opportunities for micro-optimizations that could specifically benefit the voting system. This ushered us to focus our effort on the performance aspect of integration of voting protocol with blockchain. Hence, in this thesis, we first introduce a homomorphic encryption based voting protocol that uses blockchain, Hyperledger Fabric (HLF), as bulletin board. The protocol is de- signed such that it leverages the transaction processing characteristics of underlying DLT. We then created an experiment where we designed a smart contract, set up a blockchain network and exposed the system to 40k concurrent voting transactions to profile the code of HLF. From the profile data, it was found that execution of cryptographic operations constitutes most of the transaction processing time. This led us to benchmark cryptographic libraries for SHA256 and digital signature algo- rithm and integrate the faster library into HLF for better performance. We also found that the transaction manager of HLF does not need read-write locks to ensure transaction isolation in special scenarios, which alleviates the performance drop due to lock contention. Altogether we were able to improve the throughput and latency of the baseline system by more than 30%. Lastly, we make a comparison between public and permissioned DLT based remote voting system and discuss the suitability of permissioned blockchain for the application of voting systems. / Graduate

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As the threat of supply-chain attacks grows, the need for techniques to protect software integrity likewise increases. The concept of reproducible builds is one such protection. By ensuring that a package can be rebuilt in the exact same way every time, reproducible builds allow users to notice when a package has changed even though its source code stays the same. Thus, the knowledge of which packages are reproducible and therefore easier to trust is a crucial part of this protection mechanism. Current strategies for validating and distributing this information rely on the work of a small number of individual entities with limited coordination in-between them, leading to user confusion because of the lack of a central authority. This work describes a protocol for decentralized coordination and validation of package reproducibility based on hidden votes to limit collusion and a reward scheme to ensure collaboration. The protocol uses the Hyperledger Fabric blockchain as supporting infrastructure, gaining the benefits of high availability, integrity of results and decision traceability from its decentralized nature. To test the protocol, a formal specification was written in TLA+ and validated through model checking. The results showed that, at least for the tested networks, the protocol produces valid results and enforces collaboration between users. Next steps for the project would be to build a functional prototype of the system to test its performance characteristics as well as studying the system actor assumptions made in the protocol design. / Likt hotet från leveranskedjeattacker har ökat, ökar även behoven av skyddstekniker för att säkerställa riktigheten hos mjukvara. Ett sådant typ av skydd ges av reproducerbara byggen. Om ett mjukvarupaket kan byggas exakt likadant varje gång så möjliggör det för användare att upptäcka om paketet har förändrats trots att dess källkod inte har gjort det. Att kunna veta vilka paket som är reproducerbara och därmed lättar att lita på är således en central del i denna skyddsmekanism. Nuvarande strategier för validering och distribution av sådan information bygger på arbete från ett fåtal individer och organisationer med begränsad koordinering däremellan. Detta leder till förvirring för användare på grund av bristen av en central tillitspunkt eller auktoritet. Detta arbete beskriver ett protokoll för decentralizerad koordinering och validering av paketreproducerbarhet baserat på hemliga röster för att begränsa otillåtet samarbete och ett belöningssystem för att motivera önskat samarbete. Protokollet använder blockkedjan Hyperledger Fabric som grund, med fördelarna av att få hög tillgänglighet, resultatsriktighet och spårbara beslut. En formel specifikation skrevs i TLA+ för att testa protokollet och validerades med modeltestning. Testresultatet för de testade nätverkskonfigurationerna visade att protokollet genererar valida resultat och garanterar samarbete mellan användare. De nästa stegen i projektet skulle vara att bygga en funktionell prototyp av systemet för att testa dess prestanda såväl som att studera de antaganden protokollet är designat runt.

Blockchain seems to be the hot new innovation that brings disruption to many different industries in the form of decentralization. Groups of peers can finally organize and work together without a central actor having an authority over the transactions that occur. Other than decentralization, due to the distributed and cryptographic nature of the data, the system also enjoys resilience, immutability and safety. In this thesis, we are leveraging permissioned blockchain technology to take steps towards a trustless service level agreement (SLA) management system where both service providers and customers lack the power to tamper with the contracts and their outcomes. The thesis yields a systematic literature review on the state-of-the-art within SLA management and relevant blockchain technology, a proof-of-concept working with Ericssons decentralized edge service marketplace, Nubo, and finally asimulation which evaluates how the proof-of-concept performs in terms of throughput and latency under different network loads. The simulation shows that the network works as expected, until 70 transactions per second (TPS) are reached, at which point the network is limited by throughput. / Blockchain ser ut att vara den nya teknologin som leder till stora förändringar i olika industrier i form av decentralisering. En grupp av noder kan till slut organisera sig och arbeta tillsammmans utan en central figur som styr och har kontroll över arbetet. Utöver decentralisering ger blockchain också fördelen av uthållighet, oföränderlighet och säkerhet till systemet tack vare sin kryptografiska grund. I den här studien utnyttjar vi privat blockchainteknologi för att ta steg mot en decentraliserad service level agreement (SLA) platform, där både tjänsteleverantörer och konsumenter saknar makten att manipulera kontrakt och dess resultat. Studien ger en systematisk literaturstudie på state-of-the-art inom SLA och relevant blockchain teknologi, ett bevis på koncept som fungerar tillsammans med Ericssons decentraliserade Nubo Service Marknad, och till slut en simulation som undersöker hur systemet reagerar i form av genomströmmning och responstid under olika nätverksbelastningar. Undersökningen visar att nätverket fungerar som förväntat upp till 70 transaktioner per sekund, då nätverket begränsas av genomströmning och köer bildas.

abstract: Blockchain technology enables a distributed and decentralized environment without any central authority. Healthcare is one industry in which blockchain is expected to have significant impacts. In recent years, the Healthcare Information Exchange(HIE) has been shown to benefit the healthcare industry remarkably. It has been shown that blockchain could help to improve multiple aspects of the HIE system. When Blockchain technology meets HIE, there are only a few proposed systems and they all suffer from the following two problems. First, the existing systems are not patient-centric in terms of data governance. Patients do not own their data and have no direct control over it. Second, there is no defined protocol among different systems on how to share sensitive data. To address the issues mentioned above, this paper proposes MedFabric4Me, a blockchain-based platform for HIE. MedFabric4Me is a patient-centric system where patients own their healthcare data and share on a need-to-know basis. First, analyzed the requirements for a patient-centric system which ensures tamper-proof sharing of data among participants. Based on the analysis, a Merkle root based mechanism is created to ensure that data has not tampered. Second, a distributed Proxy re-encryption system is used for secure encryption of data during storage and sharing of records. Third, combining off-chain storage and on-chain access management for both authenticability and privacy. MedFabric4Me is a two-pronged solution platform, composed of on-chain and off-chain components. The on-chain solution is implemented on the secure network of Hyperledger Fabric(HLF) while the off-chain solution uses Interplanetary File System(IPFS) to store data securely. Ethereum based Nucypher, a proxy re-encryption network provides cryptographic access controls to actors for encrypted data sharing. To demonstrate the practicality and scalability, a prototype solution of MedFabric4Me is implemented and evaluated the performance measure of the system against an already implemented HIE. Results show that decentralization technology like blockchain could help to mitigate some issues that HIE faces today, like transparency for patients, slow emergency response, and better access control. Finally, this research concluded with the benefits and shortcomings of MedFabric4Me with some directions and work that could benefit MedFabric4Me in terms of operation and performance. / Dissertation/Thesis / Masters Thesis Computer Engineering 2020

On-boarding refers to bringing in an employee to a company and granting access to new hires. However, a person may go through different stages of employment, hold different jobs by the same employer and have different levels of information access during the employment duration. A shared services organization may have either limited or wide-spread access within certain groups. Off-boarding implies the removal of access of information or physical devices such as keys, computers or mobile devices when the employee leaves. Off-boarding is the management of the separation an employee from an institution. Many organizations use different steps that constitute the off-boarding process. Incomplete tracking of an employee's access is a security risk and can lead to unintended exposure of company information and assets. Blockchain technology combines blocks of information together using a cryptographic algorithm based on the existing previous block and is verified by the peers in the blockchain network. This process creates an immutable record of employee system access providing an audit trail of access for any point in time to ensure that all access permissions can be removed once employment ends. This project proposes using blockchain technology to consolidate information across disparate groups, and to automate access removal to improve the employee off-boarding process.

abstract: Blockchain technology enables peer-to-peer transactions through the elimination of the need for a centralized entity governing consensus. Rather than having a centralized database, the data is distributed across multiple computers which enables crash fault tolerance as well as makes the system difficult to tamper with due to a distributed consensus algorithm. In this research, the potential of blockchain technology to manage energy transactions is examined. The energy production landscape is being reshaped by distributed energy resources (DERs): photo-voltaic panels, electric vehicles, smart appliances, and battery storage. Distributed energy sources such as microgrids, household solar installations, community solar installations, and plug-in hybrid vehicles enable energy consumers to act as providers of energy themselves, hence acting as 'prosumers' of energy. Blockchain Technology facilitates managing the transactions between involved prosumers using 'Smart Contracts' by tokenizing energy into assets. Better utilization of grid assets lowers costs and also presents the opportunity to buy energy at a reasonable price while staying connected with the utility company. This technology acts as a backbone for 2 models applicable to transactional energy marketplace viz. 'Real-Time Energy Marketplace' and 'Energy Futures'. In the first model, the prosumers are given a choice to bid for a price for energy within a stipulated period of time, while the Utility Company acts as an operating entity. In the second model, the marketplace is more liberal, where the utility company is not involved as an operator. The Utility company facilitates infrastructure and manages accounts for all users, but does not endorse or govern transactions related to energy bidding. These smart contracts are not time bounded and can be suspended by the utility during periods of network instability. / Dissertation/Thesis / Masters Thesis Computer Science 2019

Peer-to-Peer energy trading enables the prosumers and consumers to trade their energy in a simple services.By this the energy users have possibility to have a surplusshare of energy without any interruptions[1].But for the higher deployment of thep2p energy services, the allocation of the resources for the energy trading transactions are also challenging to model in these days. Blockchain technology, which isof a distributed ledger system and also provides a secure way of sharing the information between the peers of the network, is suitable for the proposed p2p energytrading model which can be useful for the higher scale deployments. This thesis provides an initial implementation of the p2p energy trading modelusing the blockchain and also measures the performance of the implemented modelwith the computational.A literature review is conducted for obtaining the previousstudies related to p2p energy trading using blockchain with the performance evaluation.Then the technologies related to the thesis are described and from the literaturestudies the required models are described and considered for proposing the systemmodel for the thesis. The implemented system model is also analyzed with different computational efforts for the service management functions. For generating the transactions, a Fabricclient SDK is created, which ensures that each transaction communicates with theblockchain’s smart contract for the secured transaction. Finally, after measuring thecomputational efforts, I want to observe the performance outcome for the measuredcomputational parameters so that the system’s behavior can be analyzed when thetransactions are happening between the peers by using the specific blockchain technology.

Blockchain has become the most revolutionary technology in the 21st century. In recent years, one of the concerns of world energy isn't just sustainability yet, in addition, being secure and reliable also. Since information and energy security are the main concern for the present and future services, this thesis is focused on the challenge of how to trade energy securely on the background of using distributed marketplaces that can be applied. The core technology used in this thesis is distributed ledger, specifically blockchain. Since this technology has recently gained much attention because of its functionalities such as transparency, immutability, irreversibility, security, etc, we tried to convey a solution for the implementation of a secure peer-to-peer (P2P) energy trading network over a suitable blockchain platform. Furthermore, blockchain enables traceability of the origin of data which is called data provenience. In this work, we applied a secure blockchain technology in peer-to-peer energy sharing or trading system where the prosumer and consumer can trade their energies through a secure channel or network. Furthermore, the service management functionalities such as security, reliability, flexibility, and scalability are achieved through the implementation. \\ This thesis is focused on the current proposals for p2p energy trading using blockchain and how to select a suitable blockchain technique to implement such a p2p energy trading network. In addition, we provide an implementation of such a secure network under blockchain and proper management functions. The choices of the system models, blockchain technology, and the consensus algorithm are based on literature review, and it carried to an experimental implementation where the feasibility of that system model has been validated through the output results.

On January 15, 2021, the Federal Aviation Administration published the Unmanned Aircraft System Remote Identification rule with the intention of improving airspace security regarding the use of Unmanned Aircraft. According to the rule, UAs in flight must provide the public with information such as their identification, location, and altitude. After the publication of this rule, the IETF DRIP Working Group has been working on the creation of DRIP, a protocol that meets the requirements stipulated in the rule and that guarantees that all the communication involved in the protocol is made trustworthy.  This document presents a thesis project in which Hyperledger Fabric has been studied and evaluated as an alternative to replace DRIP's DNS-based registry management. A vast research procedure combined with experiments has aided in creating a novel Blockchain-based Drone ID architecture called HL-DRIP. The designed system proposes not only how blockchain could be integrated into DRIP, but also how the rest of the Remote ID protocol could be designed, and how each of the protocol's components and participants should interact with each other to make the protocol compliant with the rule. HL-DRIP is a blockchain-based system designed to replace DRIP registry management leveraging Hyperledger Fabric and IPFS. HL-DRIP leverages x.509 and DRIP-based certificates to manage participant registration and authentication. A private IPFS network is deployed by the system's smart contract to manage participants' personal data and mitigate well-known blockchain storage issues, allowing the system to be GDPR-compliant. HL-DRIP supports i) participant registration by using certificates and HIP-based unique IDs, ii) lookups of participants' personal data, and iii) permission management.  HL-DRIP's main functionality has been prototyped and tested. The results have shown that an average of 783 participants are registered with a throughput of 8.1 transactions per second. Furthermore, an average of 648 IPFS data requests are executed with a throughput of 12.8 transactions per second.