LOKI Vote: A Blockchain-Based Coercion Resistant E-Voting Protocol

Creating an online electronic voting system that ensures coercion-resistance and end-to-end verifiability at the same time, has constituted a real challenge for a long period of time. The notion of coercion-resistance was first introduced by Juels, Catalano, and Jakobsson (JCJ) in 2005. Since that time, several research papers have appeared to address the main issue of JCJ scheme (the quadratic complexity of verifying credentials). The majority of these systems have been based on the availability of a secure web bulletin board. Despite this widespread requirement, the notion of an append-only web bulletin board remains vague, and no method of constructing such a bulletin board has been proposed in those papers. Our paper fills the gap and proposes an end-to-end verifiable e-voting protocol based on Blockchain technology. In this research work, we propose a Blockchain-based online electronic voting protocol that ensures all the security requirements expected from secure and democratic elections. Our proposal is inspired from the scheme proposed by Araujo and Traore in 2013, which is based on the work of JCJ and has a linear complexity. Called LOKI Vote, our scheme is practical for large scale elections and ensures a strong privacy for voters by using a variety of cryptographic primitives. Additionally, our protocol enhance the complexity of the old coercion resistant systems by using a new mix network, called Low Latency Anonymous Routing Protocol, which is characterized by a lower complexity and a higher level of security. Finally, we formally prove the security of LOKI Vote using the automated verification tool, ProVerif, and the Applied Pi-Calculus modeling language.