Abstract—This paper presents Riposte, a new system for anonymous broadcast messaging. Riposte is the first such system, to our knowledge, that simultaneously protects against traffic-analysis attacks, prevents anonymous denial-of-service by mali-cious clients, and scales to million-user anonymity sets. To achieve these properties, Riposte makes novel use of techniques used in systems for private information retrieval and secure multi-party computation. For latency-tolerant workloads with many more readers than writers (e.g. Twitter, Wikileaks), we demonstrate that a three-server Riposte cluster can build an anonymity set of 2,895,216 users in 32 hours. Index Terms—anonymity; messaging; privacy; private infor-mation retrieval; I.

This study provides a proof-of-concept of a newly designed verifiable voting system. The implementation elicits details in the communication and synchronization among servers, unavailable in the original design paper [M. O. Rabin and R. L. Rivest, "Efficient End to End Verifiable Electronic Voting Employing Split Value Representations. " in Proc. EVOTE ’14, Bregenz, Austria.]. The implemented system was tested on networks of virtual machines in a cluster, and its performance was evaluated based on the computational time and amount of data transferred. The preliminary results simulates elections with up to ten thousand votes. The team will conduct further work to implement the handling of server failures and the secure channels among the servers. This study demonstrates the feasibility of running large elections with more transparent voting systems, by leveraging the split-value representation and simple cryptographic primitives.