Cryptology ePrint Archive: Report 2017/778

MCMix: Anonymous Messaging via Secure Multiparty Computation

Nikolaos Alexopoulos and Aggelos Kiayias and Riivo Talviste and Thomas Zacharias

Abstract: We present ‘MCMix’, an anonymous messaging system that completely hides communication metadata and can scale in the order of hundreds of thousands of users. Our approach is to isolate two suitable functionalities, called dialing and conversation, that when used in succession realize anonymous messaging. With this as a starting point, we apply secure multiparty computation (``MC'' or MPC) and proceed to realize them. We present an implementation using a prevalent MPC system (Sharemind) that is competitive in terms of latency with previous messaging systems that only offer much weaker privacy guarantees. Our solution can be instantiated in a variety of different ways with different MPC implementations, overall illustrating how MPC is a viable and competitive alternative to mix-nets and DC-nets for anonymous communication.

Category / Keywords: cryptographic protocols / anonymity, messaging, multiparty computation

Original Publication (with major differences): 26th USENIX Security Symposium

Date: received 15 Aug 2017, last revised 16 Aug 2017

Contact author: tzachari at inf ed ac uk

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Version: 20170816:142821 (All versions of this report)

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