Paper 2026/1437

SoK: On the Design of Secure Ranking-based E-voting Systems

Abstract

Vote privacy and verifiability are two fundamental properties which must be maintained for elections. Studies in e-voting technology have demonstrated how elections may be secured through cryptographic techniques including mix-nets, homomorphic encryption, and Zero Knowledge Proofs (ZKPs). The implications and trade-offs that must be considered when designing an e-voting system using multiple cryptographic techniques for simple majority or plurality voting are well understood in the literature. However, it is less clear how these techniques affect the design process for complex e-voting systems such as those based on ranked voting. Examples include Borda count, Condorcet voting, Instant Runoff Voting (IRV), and Single Transferable Vote (STV). In this paper, we systematically analyse the cryptographic design of ranking-based e-voting systems in the literature and explore how the cryptographic techniques utilised by such systems affect the strength of their security guarantees including vote privacy and verifiability. In addition, we explore how their cryptographic designs impact social choice properties including support for various counting functions as well as flexibility in vote casting. Our findings demonstrate that ranked e-voting systems may be largely classified according to the degree of information leakage present in each solution, and that systems belonging to each of these categories share similar properties and usage of cryptographic techniques. We then discuss an overview of our findings and identify a number of open problems following our analysis. Overall, this paper serves as a comprehensive study on the state-of-the-art for secure ranked e-voting systems in the literature.