Abstract. Juels, Catalano, and Jakobsson (JCJ) proposed at WPES 2005 the first voting scheme that considers real-world threats and that is more realistic for Internet elections. Their scheme, though, has a quadratic work factor and thereby is not efficient for large scale elections. Based on the work of JCJ, Smith proposed an efficient scheme that has a linear work factor. In this paper we first show that Smith's scheme is insecure. Then we present a new coercion-resistant election scheme with a linear work factor that overcomes the flaw of Smith's proposal. Our solution is based on the group signature scheme of Camenisch and Lysyanskaya (Crypto 2004).

Abstract. Kutylowski et al. have introduced a voter-verifiable electronic voting scheme "a practical voting scheme with receipts", which provides each voter with a receipt. The voter can use her receipt to check whether her vote has been properly counted in the final tally, but she cannot use the receipt to prove others how she has voted. Another interesting property of this scheme is that, thanks to the repetitive robustness mix network, the ballot tallying phase only needs to be audited if the final results fail to achieve some conditions. However, this paper will show that this scheme is vulnerable to some threats, adversaries can not only violate voter privacy, but also forge the election result.