An efficient and provably-secure coercion-resistant e-voting protocol

We present an efficient and provably-secure e-voting protocol, which is a variant of the JCJ e-voting protocol (Juels et al., 2010). It decreases the total number of JCJ´s operations from O(n²) to O(n), where n is the number of votes or voters (whichever is the maximum). Note that since the operations under consideration are time-consuming (e.g., public-key encryption), the improvement is quite substantial. As a rough comparison, consider a nation-wide election with around ten million voters/votes. Assuming each operation takes one microsecond, and no parallelization is used, one can see a huge difference: our protocol tallies the votes in 10 seconds, while the JCJ protocol requires over 3 years to tally the votes. In order to achieve this level of efficiency, we change the ballot format and the tallying phase of the JCJ protocol. Moreover, we provide a complexity analysis and a detailed proof for coercion-resistance of our protocol.