Abstract

The Ethereum blockchain is a widely adopted global alternative to cloud computing platforms, currently used primarily for financial services. Given the large number of funds held by smart contracts and decentralized applications on top of Ethereum, there are profound security implications for both users and enterprise developers.
Over time, developers have brought more complex logic to Ethereum. For example, contracts often require access to valid, real-world data. In most cases, the system’s functionality and security are strongly dependent on the correctness and safeness of the data pushed to the blockchain. One topic of this thesis is an oracle system—infrastructure added to the blockchain to respond to this need. As contract code becomes more complex, it is increasingly likely that the code has bugs or vulnerabilities. Given smart contracts are immutable and tamper-proof, it seems impossible to upgrade a contract should a fix or patch be needed. Another topic of this thesis examines contract deployment patterns that enable and handle the upgradeability of smart contracts in Ethereum. Finally, the thesis also considers an application of oracle technology: payments made in stable currencies such as USD and not blockchain native currencies such as ETH, which are volatile in price. This thesis explains each topic in detail, evaluating the security risks of each, and examining any consequences for user trust and the degree of decentralization.