Doubly-Anonymous Crowds: Using Secret-Sharing to achieve Sender- and Receiver-Anonymity

Stefan Rass⁺, Raphael Wigoutschnigg, and Peter Schartner

Alpen-Adria-Universität Klagenfurt

Klagenfurt, Carinthia, Austria
{stefan.rass,raphael.wigoutschnigg,peter.schartner}@aau.at

Abstract

Anonymous communication is usually achieved by using overlay networks and public-key cryptography.

Besides well-established protocols, based on onion routing, various competing solutions have

been proposed in the literature. In this work we extend the Crowds system by providing sender and

adjustable receiver anonymity. Our solution is robust against a coalition of passive adversaries having

intermediate nodes in the network conquered in an attempt to discover the sender and receiver

of an observed communication. Absolute privacy for the receiver is achievable asymptotically in the

size of the network, which is beyond the control of a sender. We demonstrate that a certain level of

anonymity is achievable in finitely large networks and under full control of the sender.

Keywords: Anonymity, anonymous communication, crowds, mix-net, secret-sharing.

+Corresponding author: Stefan Rass
System Security Research Group, Institute of Applied Informatics, Universitaet Klagenfurt,
Universitaetsstrasse 65-67, 9020 Klagenfurt, Austria, Tel: +43(0)46327003715,
Email: stefan.rass@aau.at, Web: http: //www.syssec.at/stefan_rass/

Journal of Wireless Mobile Networks, Ubiquitous Computing, and Dependable Applications (JoWUA),

Vol. 2, No. 4, pp. 27-41, December 2011 [pdf]