Cryptanalysis on an E-voting Scheme over Computer Network

An electronic voting system makes it possible for the voters to cast their ballots over the computer network. Hence, voters can participate in elections without having to go to the polling places, which is more convenient and efficient. To design a practical voting scheme, Mu and Varadharajan proposed an anonymous secure electronic voting scheme to be applied over the network in 1998. However, Linet al. showed that Mu and Varadharajan´s scheme has a weakness. That is, voters can successfully vote more than once without being detected. To avoid this weakness, Lin et al. proposed a modified scheme. But, Recently, Hwang et al. showed that the Lin et al.´s modification allows the Authentication Server to identify the voters of published tickets so that voters will lose their privacy. Furthermore, they proposed an improved scheme to solve this problem and enhance the security. Unfortunately, this paper shows that Hwanget al.´s scheme has same weakness with Lin et al.´s scheme, that is, the Authentication Server can identify the voters of published tickets.