Blockchain-Based Cardinal E-Voting System Using Biometrics, Watermarked QR Code and Partial Homomorphic Encryption

A robust democracy cannot be concn. Therefore, we propose a privacy-preserving, cost-effective and verifiable blockchain-based electronic score voting scheme. Our framework is premised on a watermarked quick response (QR) code-based secure identification mechanism for creating a tamper-resistant biometric voter ID card. Two watermarked image shares, namely, owner and master shares, are created through XOR-based visual cryptography (VC) which are managed by the ID owner and a semi-trusted constituency authority (CA). Election Commission officer (ECO) commences the cryptographic system setup by distributing the secret key shares amongst all the CAs. First, voters show their share for their details verification and biometric authentication. If successful, they use the modified ElGamal homomorphic encryption to enable additive computations on their score votes while ensuring their secrecy. The integrity and validity of the encrypted vote are ensured through a non-interactive partial knowledge range proof (NIPKRP) based on the Pederson commitment protocol. On the counting day, the vote ciphertext en route to CA is subjected to progressive aggregation. This intra-constituency level computation follows the range voting paradigm. Then, CAs decrypt the resultant encrypted ballots and determine the winner for their respective constituencies after comparing the obtained scores. Accordingly, each CA creates and transmits an encrypted binary vector to ECO for pluralistic inter-constituency aggregation. Finally, ECO uses its secret key to decrypt the final encrypted aggregate vector to determine the majority winning party. If at least two maximum scores or seat counts come out to be identical, most significant bit (MSB) is given priority to break the tie. CAs can collaborate to verify the results by using their secret shares. Our proposed scheme facilitates secure, tamperproof and decentralized score aggregation for e-voting with a suitable tie-breaker. The efficacy and usability of the scheme have been reported with experimental results and security proofs.