Safavi-Naini, ReihanehAvizheh, Sepideh2024-02-202024-02-202024-02-15Avizheh, S. (2024). Secure smart contract-based computation (verifiable computation, fair two-party protocols, and resource sharing) (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.https://hdl.handle.net/1880/118193https://doi.org/10.11575/PRISM/43037A smart contract is a trusted computer program that runs on the decentralized computer that underlies a blockchain. Smart contracts are part of Web3 technology, the next generation of the Internet, and they enable distributed applications over the Internet. Smart contracts can remove intermediaries in real-world systems and have the promise of revolutionizing industries and processes in healthcare, retail, banking, government, and many more. Because of their trusted execution, smart contracts have been used as a trusted third party/referee in cryptographic protocols. They have also been used to automate processes and seamlessly incorporate cryptocurrency in payments. In this thesis, we consider the application of the smart contract as a trusted (semi-honest) third party/referee in the following problems: verifiable computation using refereed delegation of computation, fair two-party protocols that include fair private set intersection and fair exchange, and resource sharing. We show that the direct replacement of the trusted third party/referee with the smart contract can expose the protocols to new threats and attacks. We model the security of each protocol, analyze the security of the existing ones, propose new protocols that can achieve the required security guarantee in the smart contract setting, provide a proof-of-concept implementation, and evaluate their performance. Our results incorporate both secure smart contract-based cryptographic protocols and systems. We mainly propose formal models and descriptions in the real-world/ideal-world paradigm for the cryptographic protocols. We also look into the privacy in the smart contract setting. The smart contract is transparent and interactions with the smart contract are through public communication channels, thus ensuring the privacy of the parties' input and messages becomes a significant challenge in designing the protocols. We lay the foundations to define and capture privacy for a smart contract and use it to show the privacy of our cryptographic protocols.enUniversity of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.Information securityCryptographyBlockchain and smart contractsVerifiable computationFair two-party protocolsResource sharingDistributed systems securityComputer Sciencedoctoral thesis