Cryptology ePrint Archive: Report 2019/883

HoneyBadgerMPC and AsynchroMix: Practical AsynchronousMPC and its Application to Anonymous Communication

Donghang Lu and Thomas Yurek and Samarth Kulshreshtha and Rahul Govind and Rahul Mahadev and Aniket Kate and Andrew Miller

Abstract: Multiparty computation as a service (MPSaaS) is a promising approach for building privacy-preserving communication systems.However, in this paper, we argue that existing MPC implementations are inadequate for this application as they do not address fairness, let alone robustness. Even a single malicious server can cause the protocol to abort while seeing the output for itself, which in the context of an anonymous communication service would create a vulnerability to censorship and deanonymization attacks. To remedy this we propose a new MPC implementation, HoneyBadgerMPC, that combines a robust online phase with an optimistic offline phase that is efficient enough to run continuously alongside the online phase. We use HoneyBadgerMPC to develop an application case study, called AsynchroMix, that provides an anonymous broadcast functionality. AsynchroMix features a novel MPC program that trades off between computation and communication, allowing for low-latency message mixing in varying settings. In a cloud-based distributed benchmark with 100 nodes, we demonstrate mixing a batch of 512 messages in around 20 seconds and up to 4096 messages in around two minutes.

Category / Keywords: cryptographic protocols / multiparty computation, robustness

Original Publication (in the same form): ACM CCS 2019

Date: received 31 Jul 2019

Contact author: soc1024 at illinois edu

Available format(s): PDF | BibTeX Citation

Version: 20190801:132548 (All versions of this report)

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