Yes / Smart contracts have recently attracted interest from diverse fields including law and finance. Ethereum in particular has grown rapidly to accommodate an entire ecosystem of contracts which run using its own crypto-currency. Smart contract developers can opt to verify their contracts so that any user can inspect and audit the code before executing the contract. However, the huge numbers of deployed smart contracts and the lack of supporting tools for the analysis of smart contracts makes it very challenging to get insights into this eco-environment, where code gets executed through transactions performing value transfer of a crypto-currency. We address this problem and report on the use of unsupervised clustering techniques and a seed set of verified contracts, in this work we propose a framework to group together similar contracts within the Ethereum network using only the contracts publicly available compiled code. We report qualitative and quantitative results on a dataset and provide the dataset and project code to the research community. / Link to conference webpage: http://icccn.org/icccn17/workshop/

Video gaming has always been a blooming industry. With the emergence of online multi- player video games , this industry’s worth have sky rocketed. Online multiplayer video games store data of player’s credentials, in-game progress, in-game virtual assets and payment details etc. Which mean security threats to these systems are nothing new and securing these games have always meant to protect player’s data from unauthorized breach. Integration of Blockchain technology in online multiplayer video games apart from other amazing features, provides a way to prove digital ownership of virtual assets with their verifiable scarcity. Trade of these in-game virtual assets have always been a goal for online multiplayer gaming companies, but there was none enough trust-able infrastructure available which can be relied on. Blockchain just solved that problem. It provided a platform for these asset’s secure and transparent transaction between players. Topic for our research not only consider the security challenges in online games but specifi- cally blockchain based online multiplayer games. This adaptation is still new and there is need of consideration of new security challenges. In this dissertation we try to bring out some important challenges related to security of blockchain based online multiplayer video games. There are currently no studies around security concerns and challenges of the integration of the online multiplayer video games in the emerging blockchain systems. In order to fill in the gap, this dissertation discusses and identifies two main security concerning questions related to this domain. Also this dissertation provides basic steps for expanding future research and application in this joint domain.

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.

This study examines small and medium scale specialty crop growers’ preferences for marketing contract attributes and willingness to adopt blockchain-based smart contracts. The data used were collected using an online survey and discrete choice experiment. Findings indicate that farmers prefer higher average prices, cash, check or electronic bank payment over cryptocurrency, and immediate payment upon product delivery over delayed payment. When choosing a contract, farmers viewed traditional text-based contracts and digital platforms with automated smart contracts equivalently, on average. On average, farmers showed no preference for providing and not providing traceability lot codes to buyers, and between choosing a contract and marketing their products as usual. Although we find that some farmers prefer to provide traceability lot codes to buyers while others do not, and some farmers prefer having a contract option while others do not. These insights could be useful to buyers and specialty crop farmers seeking to contract.

Digitalization has led to the development of electronic voting systems, which in turn influences electoral integrity. Since the fairness of elections plays such an important part for democracy, the security aspects that keep an election's integrity and fairness are of great importance and thus, is the objective of this research. The research question this study aims to answer is “What security differences and / or similarities can be identified between End-to-End and blockchain-based voting systems?”. A comparative systematic literature review was done in order to answer the research question, which started by finding relevant literature needed for the analysis. After identifying the necessary articles, advantages and disadvantages for End-to-End and blockchain-based voting systems were outlined and then compared in a truth table (table 5). The results showed that the two systems share similar characteristics such as: verifiability, voter anonymity / ballot secrecy, integrity and the lack of scalability. Whereas the main differences are found in relation to how susceptible each system is to attacks. This leads to the conclusion that the biggest difference identified between blockchain-based and End-to-End systems is their susceptibility to attacks.

Syfte: Studiens syfte är att analysera huruvida korruption i biståndsprocesser bättre kan hanteras via de blockkedjebaserade lösningarna kryptovalutor, smarta kontrakt och tokens, jämfört med traditionellt biståndsgivande. Vidare ämnar studien applicera resultaten från fallstudien på generella avtalsprocesser exponerade mot opportunism, för att analysera huruvida de blockkedjebaserade lösningarna bättre kan hantera transaktionskostnader jämfört med traditionella avtalslösningar. Bakgrund: Informationsasymmetrier, begränsad rationalitet och strategiskt beteende resulterar i tillitsproblematik vid avtalsprocesser, vilket ökar transaktionskostnaderna (Williamson, 1974). Biståndsprocesser är extra exponerade mot opportunistiskt beteende i form av korruption, vilket leder till att en stor del av biståndet försvinner på vägen (Transparency International, 2017). Blockkedjebaserad teknik ger möjligheten att ingå avtal utan tillit till motparten, men  lösningen är inte optimal för alla typer av avtal. Det motiverar en analys om huruvida tekniken kan hantera transaktionskostnader i biståndsprocesser bättre än traditionellt biståndsgivande. Genomförande: Studiens primärdata inhämtades via semi-strukturerade intervjuer med två svenska biståndsorganisationer och två experter inom blockkedjetekniken. Utöver intervjuerna genomfördes även en litteraturstudie och den insamlade empirin analyserades utifrån ett transaktionskostnadsperspektiv. Slutsats: Blockkedjebaserade lösningar kan hantera transaktionskostnader bättre än traditionellt biståndsgivande när Greenspans (2015) fem kriterium är uppfyllda. Kontexten, avtalets karaktär och avtalsparternas preferenser är de avgörande faktorerna huruvida kriterierna uppfylls i såväl biståndsgivande som generella avtalsprocesser. En ökad transparens, öppenhet och censurresistens måste värderas högre vid implementering än de medföljande säkerhetsriskerna. / Purpose: The purpose of this study is to analyze whether corruption in aid processes better can be managed through the blockchain-based solutions cryptocurrencies, smart contracts and tokens, in comparison to traditional donation of aid. The study also aims to apply the results from the case study to general contractual processes exposed to opportunistic behavior, to analyze whether the blockchain-based solutions better can manage the transaction costs in comparison to traditional contractual solutions. Background: Asymmetric information, bounded rationality and strategic behavior result in trust issues in contractual processes, which increases transaction costs (Williamson, 1974). Aid processes are particularly exposed to opportunistic behavior in form of corruption, which leads to aid disappearing on the way (Transparency International, 2017). Blockchain-based technology enables contractual relationships without trusting the counterpart, but is not an optimal solution for all types of contracts. This provides incentives for a further analysis whether the technology can manage transaction costs in aid processes better than traditional donation of aid. Completion: The study´s primary data was obtained through semi-structed interviews with two Swedish aid organizations and two experts in blockchain technology. A literature review was made and the empirical data was analyzed from a transaction cost perspective. Conclusion: Blockchain-based solutions can manage transaction costs better than the traditional donation of aid when Greenspan´s (2015) five criteria is met. The context, the characteristics of the contract and the preferences of the contracting parties are the decisive factors whether the criteria are met in the aid donation process and in general contractual processes. Increased transparency, openness and censor resistance must be valued higher when implementing the technology than the following security risks. / <p>Bilagor är inkluderade</p>

在後數位化時代，有無數的數位服務生態圈在爭奪著有限的市場。而要贏得這場競爭最好的方式就是遵照服務設計的理論來滿足顧客的渴望。本研究期望運用科技化的輔助方式來幫助服務設計者建立一個以顧客主導邏輯為基礎的區塊鏈服務生態系統。在這個方法裡面，我們必須要解譯服務設計者的服務價值主張，並且找出與之相關的價值活動來作為之後服務設計的樣本。最後透過服務渴望度、創新度以及利害關係人認可程度三個面向來衡量整個價值結構設計是否可行並有發展潛力。 / In the post-digital era, there are countless digital ecosystems to fight for the limited market share. Using service design theory to fulfill customers’ desire is the best way to win the competence. This paper proposes a technology facilitating approach to help service designers configure their blockchain-based service ecosystem with customer-dominate logic. We rephrase the service value proposition inputted by service designers and filtering related value activities as the model of designed ecosystem. To make the decentralized ecosystem become a destination, we have to examine the value configuration from three different perspectives which are desirability, disruption, and consensus. These three dimensions provide service designers with a method that can help assess if a configuration is making sense or not. After all, this paper is aimed to support service designers to create a digital destination ecosystem by recommending activities and evaluating score of ecosystem configuration.

Information technology systems are essential for most businesses as they facilitate the handling and sharing of data and the execution of tasks. Due to connectivity to the internet and other internal networks, these systems are susceptible to cyberattacks. Computer worms are one of the most significant threats to computer systems because of their fast self-propagation to multiple systems and malicious payloads. Modern worms employ obfuscation techniques to avoid detection using patterns from previous attacks. Although the best defense is to eliminate (patch) the software vulnerabilities being exploited by computer worms, this requires a substantial amount of time to create, test, and deploy the patches. Worm containment techniques are used to reduce or stop the spread of worm infections to allow time for software patches to be developed and deployed. In this dissertation, a novel blockchain-based collaborative intrusion prevention system model is introduced. This model is designed to proactively contain zero-day and obfuscated computer worms. In this model, containment is achieved by creating and distributing signatures for the exploited vulnerabilities. Blockchain technology is employed to provide liveness, maintain an immutable record of vulnerability-based signatures to update peers, accomplish trust in confirming the occurrence of a malicious event and the corresponding signature, and allow a decentralized defensive environment. A consensus algorithm based on the Practical Byzantine Fault Tolerance (PBFT) algorithm is employed in the model. The TLA+ formal method is utilized to check the correctness, liveness, and safety properties of the model as well as to assert that it has no behavioral errors. A blockchain-based automatic worm containment system is implemented. A synthetic worm is created to exploit a network-deployed vulnerable program. This is used to evaluate the effectiveness of the containment system. It is shown that the system can contain the worm and has good performance. The system can contain 100 worm attacks a second by generating and distributing the corresponding vulnerability-based signatures. The system latency to contain these attacks is less than 10 ms. In addition, the system has low resource requirements with respect to memory, CPU, and network traffic. / Graduate