HAC-Bchain: A Secure and Scalable Blockchain-Shard Based E-Voting System

Voting is a fundamental right of citizens in a democratic country and crucial for any thriving democracy. Reliable voting systems are essential for free and fair elections in the modern era. Biometric Electronic Voting Machines (EVMs) address many issues with paper-ballot systems, but their closed-source nature undermines voter trust. Traditional election systems are also vulnerable to cyberattacks. In this paper, we propose a hybrid blockchain-based electronic voting system (HAC-Bchain) to address the limitations of conventional e-voting systems and ensure a secure, auditable, tamper-proof, transparent, and privacy-preserving voting process. A scripting system for our blockchain facilitates a limited set of predefined operations for each layer, which helps authoritative figures to manage the election securely. We also combine a category-based sharding mechanism with the HAC-Bchain hybrid approach to create more data-concentrated shards, which improves scalability, performance, and data availability. Furthermore, we compare and discuss the performance and efficiency of different sharding configurations. Our experiments shed new light on the overall security, performance, and scalability of blockchain-based evoting systems.