Efficient hybrid-encryption-based optimistic Mix-net protocol

Abstract

An efficient hybrid-encryption-based Mix-net is presented that is much faster than all previous Mix-nets with public verifiability when all mix-servers execute the mixing protocol honestly (the usual case).The improvement by taking an “optimistic” and hash-based approach to verify the correctness of mixing is achieved without requiring complex and costly zero-knowledge proofs.Only two element-wise testing processes with low-cost computations of hash functions are involved to make certain messages are not manipulated by a cheating server.An efficient integration of public-key and symmetric-key operations also speeds up the mixing.As a result,the computational task of each mix-server is almost independent of the number of mix-servers except for some negligible tasks.Anyone can verify the correctness of a result rapidly by computing a few exponentiations.The scheme is robust,too.Those characteristics make it very suitable for large scale electronic voting.

Keywords

• anonymous communication;electronic voting;mix network;hybrid encryption