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 malicious 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.
Pynchon Gate @cite_16 builds a private point-to-point messaging system from mix-nets and PIR. Clients anonymously upload messages to email servers using a traditional mix-net and download messages from the email servers using a PIR protocol. could replace the mix-nets used in the Pynchon Gate system: clients could anonymously write their messages into the database using and could privately read incoming messages using PIR.
@cite_16
2134698082
We describe the Pynchon Gate, a practical pseudonymous message retrieval system. Our design uses a simple distributed-trust private information retrieval protocol to prevent adversaries from linking recipients to their pseudonyms, even when some of the infrastructure has been compromised. This approach resists global traffic analysis significantly better than existing deployed pseudonymous email solutions, at the cost of additional bandwidth. We examine security concerns raised by our model, and propose solutions.