Coercion Resistance in a Practical Secret Voting Scheme for Large Scale Elections

We propose a novel framework to combine efficient coercion resistance with increased levels of privacy in electronic voting. Our scheme can be considered as an extension of the blind signature based voting protocol of Fujioka, Okamoto and Ohta (FOO) that aims to merge it with the well known coercion resistance framework proposed by Juels, Catalano and Jakobsson (JCJ), where each voter can cast multiple votes, authenticated using nonymous credentials. Our proposal has an additional benefit, since it deals with coercion resistance in a more efficient manner, by taking advantage of the function splitting architecture between the participating authorities from FOO to reduce the quadratic complexity of identifying and removing coerced votes, which are cast with fake credentials, as in JCJ. To this end we utilise a method of converting digital signatures to group signatures due to Petersen.