The digitization of democratic processes promises greater accessibility but presents challenges in terms of security, privacy, and verifiability. Existing electronic voting systems often rely on centralized architectures, creating single points of failure and forcing too much trust in authorities, which contradicts democratic principles. This thesis addresses the challenge of creating a secure, private e-voting system with minimized trust dependencies designed for the most versatile personal device: the smartphone. We introduce SmartphoneDemocracy, a novel e-voting protocol that combines three key technologies: the emerging European Digital Identity (EUDI) Wallet for Sybil-resistant identity verification, Zero-Knowledge Proofs for privacy-preserving validation, and a peer-to-peer blockchain (TrustChain) for a resilient, serverless public bulletin board. Our protocol enables voters to register and cast ballots anonymously and verifiably directly from their smartphones. We provide a detailed protocol design, a security analysis against a defined threat model, and a performance evaluation demonstrating that the computational and network overhead is feasible for medium- to large-scale elections. By developing and prototyping this system, we demonstrate a viable path to empower citizens with a trustworthy, accessible, and user-controlled digital voting experience.

When designing critical software, great care must be taken to guarantee its correctness. Refactoring is one of the techniques used to improve code readability, maintainability, and other factors without changing functionality. Thus, to ensure that it is properly applied, automated tools are used to perform refactoring. To ensure that the code remained correct, we verified the correctness of the tool actions using formal proof. This is assisted by a dependently typed language Agda, which, when used as a proof assistant, can directly support us by ensuring the soundness of the steps taken. We consider the refactoring of currying and its counterpart, uncurrying, using a small proof-of-concept functional programming language with intrinsically typed terms and de Bruijn indices. Furthermore, we proved the retained properties of well-typedness, termination, and value relation of the input program. Finally, we argue that this research could be extended to the full implementation of Haskell, as well as applied to other languages and similar refactorings.