Robust electronic voting: Introducing robustness in Civitas

Civitas is a remote electronic voting system, providing verifiability and some coercion resistance. It is a refinement of a cryptographic voting scheme proposed by Juels, Catalano, and Jakobsson in 2005. In this paper we analyze the robustness of Civitas. In electronic voting, robustness has different interpretations. Tally availability is the most common interpretation. In addition to this interpretation, we also consider the availability of the election for every willing voter (voting availability). For both criteria a formal definition is provided. It is shown, that Civitas does not comply with this definition. Therefore, we extend Civitas in order to overcome this shortcoming. This extension also tackles a coercion resistance vulnerability which was identified by Küsters and Truderung in 2009.