Efficient Decentralized Random Commitment Key Generation for Mixnet Shuffle Proof

In this paper, we propose a new commitment key generation method for the mixnet shuffle proof developed by Bayer-Groth in Eurocrypt’ 12. The problem of the shuffle proof algorithm is that it gives too much power to a single authority: It has been shown that the authority, who creates commitment keys and generates proofs for verifying electronic voting (e-voting) results, also can produce malicious verification proofs by logging the exponents of commitment keys. We suggest a new way to decentralize the commitment key generation process by allowing multiple parties to jointly participate in the commitment key generation. Therefore, any of the parties, even who operating e-voting system, cannot know the exponents of commitment keys fully. Therefore, our suggestion distributes the power that is concentrated on the single authority and makes the verification process of the proof more sound and prudent.