Saba Eskandarian (University of North Carolina at Chapel Hill), Dan Boneh (Stanford University)

This paper studies the role of multiparty shuffling protocols in enabling more efficient metadata-hiding communication. We show that the process of shuffling messages can be expedited by having servers collaboratively shuffle and verify secret-shares of messages instead of using a conventional mixnet approach where servers take turns performing independent verifiable shuffles of user messages. We apply this technique to achieve both practical and asymptotic improvements in anonymous broadcast and messaging systems. We first show how to build a three server anonymous broadcast scheme, secure against one malicious server, that relies only on symmetric cryptography. Next, we adapt our three server broadcast scheme to a k-server scheme secure against k-1 malicious servers, at the cost of a more expensive per-shuffle preprocessing phase. Finally, we show how our scheme can be used to significantly improve the performance of the MCMix anonymous messaging system.

We implement our shuffling protocol in a system called Clarion and find that it outperforms a mixnet made up of a sequence of verifiable (single-server) shuffles by 9.2x for broadcasting small messages and outperforms the MCMix conversation protocol by 11.8x.

View More Papers

Repttack: Exploiting Cloud Schedulers to Guide Co-Location Attacks

Chongzhou Fang (University of California, Davis), Han Wang (University of California, Davis), Najmeh Nazari (University of California, Davis), Behnam Omidi (George Mason University), Avesta Sasan (University of California, Davis), Khaled N. Khasawneh (George Mason University), Setareh Rafatirad (University of California, Davis), Houman Homayoun (University of California, Davis)

Read More

Trust and Privacy Expectations during Perilous Times of Contact...

Habiba Farzand (University of Glasgow), Florian Mathis (University of Glasgow), Karola Marky (University of Glasgow), Mohamed Khamis (University of Glasgow)

Read More

Demo #8: Identifying Drones Based on Visual Tokens

Ben Nassi (Ben-Gurion University of the Negev), Elad Feldman (Ben-Gurion University of the Negev), Aviel Levy (Ben-Gurion University of the Negev), Yaron Pirutin (Ben-Gurion University of the Negev), Asaf Shabtai (Ben-Gurion University of the Negev), Ryusuke Masuoka (Fujitsu System Integration Laboratories) and Yuval Elovici (Ben-Gurion University of the Negev)

Read More

Demystifying Local Business Search Poisoning for Illicit Drug Promotion

Peng Wang (Indiana University Bloomington), Zilong Lin (Indiana University Bloomington), Xiaojing Liao (Indiana University Bloomington), XiaoFeng Wang (Indiana University Bloomington)

Read More