How to design the faultless bribery and coercion prevention electronic voting scheme

Bribery and coercion usually represents two serious problems in conventional voting systems. However, these problems become acute in electronic voting (e-voting) scheme due to its mobility. Recently, Wu et al. first classified the methods used to perform bribery and coercion into five levels. They proposed a level-four secure scheme which can prevent bribery and coercion even when a voter's voting processes are monitored by a briber or coercer. However, their scheme still cannot achieve the highest level -- level-five secure e-voting scheme. That is, even the major secret used for voting is revealed, a voter still can cast his/her vote without violate his/her volition. By introducing an extra setup phase and a slightly modification on the off-line disputation phase on Wu et al.'s scheme, we propose a level-five secure e-voting scheme. The proposed scheme inherits most of the advantages of Wu et al.'s scheme in the security requirement.