Khader, D., Smyth, B., Ryan, P.Y.A., & Hao, F. (2011) A Fair and Robust Voting System by Broadcast. In Proceedings of sixteenth Nordic Conference in Secure IT Systems (NordSec'11).
In 2010, Hao, Ryan & Zieliński proposed a two-round decentralized voting protocol that is efficient in terms of rounds, computation, and bandwidth. However, their protocol has two issues. First, as stated in the original paper, if some voters abort in the second round, they effectively disrupt the election, hence causing a DoS attack. Second, the last voter in the second round knows the election result earlier than others, which indicates a lack of fairness. Both drawbacks are generally applicable to other decentralized e-voting protocols as well. In this work we overcome these drawbacks: we introduce a recovery round to overcome DoS attacks and propose a commitment round to prevent a voter changing her vote once partial results are known. Finally, we provide a formal proof of ballot secrecy using provable security techniques.