Efficient, usable and Coercion-Resistant Blockchain-Based E-Voting

In Sarier (2021), the author presents a practical biometric-based non-transferable credential scheme that maintains the efficiency of the underlying Brands’ Credential (BC). In this paper, we design a new Blockchain-Based E-Voting (BBEV) scheme to solve the open problem of voter authentication in BBEV by combining the system of Sarier (2021) with encrypted Attribute Based Credential (ABC), where the latter is also based on BC. Despite of its efficiency, encrypted ABC is employed the first time² in the context of e-voting to achieve efficient, usable, anonymous, auditable, verifiable, and coercion-resistant BBEV for small/medium scale elections. To the best of our knowledge, the system is the first pre-encrypted digital ballot system for a non-transferable and user-centric BBEV that depends on the one-show BC both for biometric authentication and ballot generation leading to a natural prevention against double voting. Even though the system is instantiated with Bitcoin (BTC) due to its prevalence and various coin mixers available for anonymity, the system is designed to be generic in addition to avoiding complex smart contracts and heavy crypto-primitives. Thus, the new BBEV scheme can be extended to large-scale elections for public Blockchains with higher throughput/cheaper transaction fees compared to BTC/BCH or other UTXO-based Blockchains such as BSV. We analyze BBEV in terms of the highest security notion in e-voting, namely Coercion Resistance together with an efficiency estimate of its voting phase. Also, we evaluate BBEV in terms of the Multos smartcard implementation, where BC-based systems are already shown to be the most efficient on Multos. Finally, a cost analysis based on the last US presidential election data shows that, the new BBEV is advantageous over the traditional one if implemented for three consecutive elections.