Blockchain-Based Voting System with OTP Authentication and Off-Chain Privacy Preservation

Abstract

A secure and transparent blockchain-based voting system is proposed, designed to preserve voter anonymity, prevent tampering, and ensure one-vote-per-user compliance in decentralized digital elections. The system introduces a lightweight voter authentication layer using one-time password (OTP) verification, with off-chain hashed identity storage to prevent exposure of personal data. Unlike traditional models that rely solely on smart contract logic, this approach strengthens the end-to-end security boundary by validating user eligibility before on-chain interaction. Votes are cast through smart contracts deployed on a public blockchain, ensuring immutability and auditability, while maintaining voter anonymity by detaching authentication logic from vote recording. To address performance bottlenecks and storage limitations, non-critical identity data is excluded from the blockchain, with hashed authentication tokens acting as cryptographic proofs of voter legitimacy. The proposed method was validated through simulation of small-scale voting rounds, demonstrating secure vote casting with a rejection rate of 100% for duplicate or invalid attempts. Average authentication time remained under 200 milliseconds per session. The modular design facilitates integration with government or institutional ID systems and supports anonymous and verified voting modes, making it adaptable for educational, corporate, or civic deployment. Future iterations will explore zero-knowledge proofs to further enhance privacy guarantees while preserving voter eligibility validation.