Lab Lunch: 24 April 2018 - Thomas Zachiarias

Title: MCMix: Anonymous Messaging via Secure Multiparty Computation

Abstract:

Edward Snowden's revelations in 2013 on the power of massive surveillance programmes, were a turning point regarding the awareness on internet privacy hazards.  In what is often called the Post-Snowden Era, security researchers have increased their efforts at implementing privacy-enhancing technologies that could also protect people's  metadata on top of the standard plaintext hiding supported by SSL/TLS protocols. Advances on this area of research, called anonymous communications, is the main focus of the H2020 project PANORAMIX that I am involved and is coordinated by Prof. Aggelos Kiayias.

In this, talk I will present the 'MCMix' system [USENIX Security 2017] that addresses the problem of anonymous messaging and is a joint work with Nikos Alexopoulos [TU Darmstadt], Aggelos Kiayias, and Riivo Talviste [Cybernetica AS].

MCMix is 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 take the novel approach by applying Secure Multiparty Computation (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.

Furthermore, we wish to take a step further beyond an academic proof of concept, and provide MCMix as a real-world service.  To this end, EUDIN PhD student Yiannis Tselekounis, following the work of former MSc and PhD UEDIN student Chris Cambell, is currently developing MCMix client in Android, soon to be available for testing by real users.