Privacy and Usability Aspects of Public Blockchains

Abstract

The widespread adoption of blockchain technology (BT) has brought significant attention to concerns surrounding user privacy. As a decentralized and distributed system, BT enables users to store and transfer information securely and transparently. However, its public nature also means that anyone can access its data, potentially resulting in privacy breaches. To address these concerns, several privacy-preserving techniques have emerged to mitigate the risks associated with the public blockchain and safeguard user privacy. This thesis focuses on privacy concerns specific to the Bitcoin blockchain. Its primary objective is to assess the efficiency of the existing privacy-preserving techniques within the Bitcoin blockchain, highlighting their limitations and identifying emerging challenges. Moreover, the thesis investigates users’ mental models in employing privacy-preserving techniques for the blockchain through interviews and questionnaires. By gaining insights into users’ perspectives and expectations regarding privacy-preserving techniques, this approach contributes to a comprehensive understanding of users’ perceptions. A key challenge in the adoption of privacy-preserving techniques in BT is their usability for ordinary users. To overcome this challenge, the thesis conducts a comprehensive usability study of wallets that integrate add-on privacy techniques. This study incorporates a cognitive walkthrough and a user study based on usability and design criteria. The resulting findings provide insights and guidance to developers on enhancing the usability of these wallets and making them more user-friendly. This thesis aims to advance the comprehension and enhancement of user privacy within BT, with a specific focus on the Bitcoin blockchain. The research findings have the potential to guide the development of novel, effective, and efficient privacy-preserving techniques for protecting user privacy. Moreover, the study’s insights on the usability aspects of privacy wallets can assist developers in creating user-friendly and accessible privacy-preserving techniques for blockchain transactions.