Distributed Verification of Mixing - Local Forking Proofs Model

Simple and efficient hash-based verifiable mixing for remote electronic voting

“…Last but not least, as mentioned in [6], conceptual complexity should also be reduced, otherwise users may not trust a system they cannot fully understand.…”

“…This technique keeps a non-negligible probability of small alterations not being detected and requires most Mixing Elements to keep honest, otherwise, privacy may be compromised (other systems, like the one presented in this paper, maintain privacy as long as at least one is not corrupted). The authors in [6] propose local forking as a technique in which each verifier only checks the correctness of a small part of the mixing. Clearly, this technique does fully satisfy the verifiability property.…”

“…Proposals in the literature prove shuffling correctness by using very complex zero-knowledge proofs that introduce a very high computational cost. This cost is usually measured as the number of modular exponentiations to be performed as a function of the number of cast ballots, n. For instance, according to [6], 12n exponentiations are required in [26], 10n in [13,27], 8n in [16] and about 6n in [29]. Communication cost of such schemes is linear in n. For instance, 6388n bits for [13] and 2528n for [16].…”