Rabbit-Mix: Robust Algebraic Anonymous Broadcast from Additive Bases


Chongwon Cho and Samuel Dittmer, Stealth Software Technologies Inc.; Yuval Ishai, Technion; Steve Lu, Stealth Software Technologies Inc.; Rafail Ostrovsky, UCLA


We present Rabbit-Mix, a robust algebraic mixing-based anonymous broadcast protocol in the client-server model. Rabbit-Mix is the first practical sender-anonymous broadcast protocol satisfying both robustness and 100% message delivery assuming a (strong) honest majority of servers. It presents roughly 3x improvement in comparison to Blinder (CCS 2020), a previous anonymous broadcast protocol in the same model, in terms of the number of algebraic operations and communication, while at the same time eliminating the non-negligible failure probability of Blinder. To obtain these improvements, we combine the use of Newton's identities for mixing with a novel way of exploiting an algebraic structure in the powers of field elements, based on an {\em additive 2-basis}, to compactly encode and decode client messages. We also introduce a simple and efficient distributed protocol to verify the well-formedness of client input encodings, which should consist of shares of multiple arithmetic progressions tied together.

Open Access Media

USENIX is committed to Open Access to the research presented at our events. Papers and proceedings are freely available to everyone once the event begins. Any video, audio, and/or slides that are posted after the event are also free and open to everyone. Support USENIX and our commitment to Open Access.