Auflistung nach Autor:in "Haenni, Rolf"
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- KonferenzbeitragAchieving meaningful efficiency in coercion-resistant, verifiable Internet voting(5th International Conference on Electronic Voting 2012 (EVOTE2012), 2012) Spycher, Oliver; Koenig, Reto; Haenni, Rolf; Schläpfer, MichaelIn traditional voting schemes with paper, pens, and ballot-boxes, appropriate procedures are put in place to reassure voters that the result of the tally is correct. Considering that in Internet voting errors or fraud will generally scale over a much greater fraction of votes, the demand to get strong reassurances as well, seems more than justified. With the ambition of offering a maximum degree of transparency, so-called verifiable schemes have been proposed. By publishing the relevant information, each voter may verify that her vote is included in the final tally and that accepted votes have been cast using proper voting material. Remarkably, this can be done while guaranteeing the secrecy of the ballot at the same time. On the negative side, high transparency will generally make it easier for voters to reveal how they voted, e.g., to a coercer. In this paper we propose an Internet voting protocol that is verifiable and simultateously makes it practically impossible for vote buyers or coercers to elicit the voters' behaviour. We compare its efficiency with existing work under equal degrees of coercion-resistance using an appropriate measure (δ). The contribution of our scheme lies in its efficiency during the most critical phases of the voting procedure, i.e., vote casting and tallying. Moreover, during these phases, efficiency is insensitive to the desired degree of coercion-resistance.
- KonferenzbeitragCoercion-resistant hybrid voting systems(4th International Conference on Electronic Voting 2010, 2010) Spycher, Oliver; Haenni, Rolf; Dubuis, EricThis paper proposes hybrid voting systems as a solution for the vote buying and voter coercion problem of electronic voting systems. The key idea is to allow voters to revoke and overrule their electronic votes at the polling station. We analyze the potential and pitfalls of such revocation procedures and give concrete recommendations on how to build a hybrid system offering coercion-resistance based on this feature. Our solution may be of interest to governments, which aim at integrating paper-based and electronic voting systems rather than replacing the former by the latter.
- KonferenzbeitragA lightweight implementation of a shuffle proof for electronic voting systems(Informatik 2014, 2014) Locher, Philipp; Haenni, RolfIn the usual setting of a verifiable mix-net, an input batch of ciphertexts is shuffled through a series of mixers into an output batch of ciphertexts while hiding the mapping between input and output and preserving the plaintexts. Unlike shuffling, proving the correctness of a shuffle is relatively expensive and difficult to implement. In this paper, we present a new implementation of a shuffle proof based on the proof system proposed by Wikström and Terelius. The implementation offers a clean and intuitive application programming interface and can be used as a lightweight cryptographic component in applications of verifiable mix-nets. Verifiable electronic voting is the most prominent target application area.1
- KonferenzbeitragVerifizierbare Internet-Wahlen an Schweizer Hochschulen mit UniVote(INFORMATIK 2013 – Informatik angepasst an Mensch, Organisation und Umwelt, 2013) Dubuis, Eric; Fischli, Stephan; Haenni, Rolf; Hauser, Severin; Koenig, Reto E.; Locher, Philipp; Ritter, J.; Bergen, Philémon vonDieser Bericht dokumentiert den erstmaligen Einsatz des Internet-Wahlsystems UniVote anlässlich der Wahl des Studierendenrats an drei Schweizer Hochschulen im Frühling 2013. Mittels kryptographischer Methoden garantiert UniVote eine anonyme und geheime Stimmabgabe und ermöglicht gleichzeitig die Verifizierung des Wahlresultats durch Dritte mittels unabhängiger Software. Dazu werden sämtliche Wahldaten veröffentlicht.
- KonferenzbeitragWhy public registration boards are required in E-voting systems based on threshold blind signature protocols(4th International Conference on Electronic Voting 2010, 2010) Koenig, Reto E.; Dubuis, Eric; Haenni, RolfIn this paper, we demonstrate that e-voting protocols based on threshold blind signatures from multiple authorities allow a coalition of eligible voters to cast more than votes. This property presents a serious violation of the principles of democracy in the voting process. We analyze the applicability of this violation and provide a generic solution using a public registration board and modified threshold signature schemes.