This Master’s Thesis main purpose is to identify the perceptions of Cyber Security Professionals on Blockchain Technology and whether it could potentially become a substitutefor the current data security systems or not. A literature review was initially performed in order to explore previous related research on the field of Cyber Security, its infrastructure andthe main aspects of Blockchain Technology.Qualitative research was conducted in regards to the participants’ perceptions. Morespecifically, individual interviews were held with each one of the participants all of whom are professionals in the field of Cyber Security. Five different themes emerged from theinterviews which were performed by asking open-ended questions and holding a dialogue with the participants. Those themes start with (1) their opinions on current data security infrastructure and methods. Following that theme a half hour presentation on basic blockchain operations and applications were held in order to identify their (2) current understanding onblockchain. (3) Discussions were held in regards to blockchain’s scalability and sustainability,followed by (4) the security of Blockchains. In the end the (5) fifth and final theme covered the main purpose of this master’s thesis which is whether blockchain can be implemented asan alternate technology on data privacy and security.This Master’s Thesis contributes to the current knowledge on Blockchain within the field ofinformatics by providing the perceptions of Cyber Security Professionals in regards to its operation and implementation. Furthermore it aims to identify whether any possible applications of blockchain technology could be suggested for future implementation in thedomain of data security.The discussion summarizes the empirical findings acquired from the interviews and theperceptions of the participants on Blockchain Technology. By exploring the themes thatemerged from the interviews, it is clearly evident that blockchain is still not a technology thatcan be trusted as an alternative to the current security infrastructures and methods according to the participants. Despite that fact a lot of advantages and optimistic elements were derived since blockchain’s immutability and security demonstrates a high level of tamperingresistance, thus making it suitable as a technology within the Information security industry. Incase blockchain manages to overcome its shortcomings it could prove to be a necessary tool in data privacy and security.

Smart contracts are self-executing electronic contracts. Amongst its deployed applications in the digital world is providing a decentralized and transparent method for executing transactions of cryptocurrencies on blockchains. Our thesis aims to investigate the mechanisms influencing execution of smart contracts across different blockchain networks when it comes to transactions of their native tokens. With a focus on the Ethereum, Avalanche, Cardano, Chainlink, and Binance blockchain technologies, an experiment is conducted which involves transferring native tokens on each of the blockchains to obtain results of the speed of each of the transfers and their respective transaction costs. The developed problem statement revolves around understanding the blockchain characteristics and smart contract implementations that contribute to these results. Properties of smart contracts and blockchain networks are established, which form the qualitative data components of our research. Further, we perform an analysis and evaluation of the quantitative results of our experiment to form a connection between each of the blockchains’ qualitative properties and their respective performance. Architecture, gas limit, gas price, and network congestion are identified as key determinants of gas fees and transaction costs. The choice of consensus mechanism, block time, and scalability solutions also play a significant role in transaction speed and time to finality. We believe our discoveries contribute to enhancing the implementation of smart contracts in the context of cryptocurrencies. / Smarta kontrakt är självutförande elektroniska kontrakt. Bland dess tillämpningar i den digitala världen ingår att tillhandahålla en decentraliserad och transparent metod för att utföra transaktioner av kryptovalutor på blockkedjor. Vår examensarbete syftar till att undersöka de mekanismer som påverkar utförandet av smarta kontrakt över olika blockkedjenätverk när det gäller transaktioner av deras valutor. Med fokus på Ethereum, Avalanche, Cardano, Chainlink och Binance blockkedjeteknologier genomförs ett experiment som innebär överföring av valutor på varje blockkedja för att erhålla resultat av hastigheten för varje överföring och deras respektive transaktionskostnader. Det utvecklade problemet kretsar kring förståelsen av blockkedjekaraktäristik och smarta kontraktsimplementeringar som bidrar till dessa resultat. Egenskaper hos smarta kontrakt och blockkedjenätverk fastställs, vilket utgör de kvalitativa datakomponenterna i vår forskning. Dessutom genomför vi en analys och utvärdering av de kvantitativa resultaten från vårt experiment för att skapa en koppling mellan varje blockkedjas kvalitativa egenskaper och deras respektive prestanda. Arkitektur, gasgräns, gaspris och nätverksöverbelastning identifieras som avgörande faktorerna för gasavgifter och transaktionskostnader. Valet av konsensusmekanism, blocktid och skalbarhetslösningar spelar också en betydande roll för transaktionshastighet och tidsmässig avslutning. Vi anser att våra upptäckter bidrar till att förbättra implementeringen av smarta kontrakt i sammanhanget av kryptovalutor.