Security Analysis of
Accountable Anonymity in Dissent

Ewa Syta, Henry Corrigan-Gibbs, Shu-Chun Weng, David Wolinsky, Bryan Ford
Yale University

Aaron Johnson
U.S. Naval Research Laboratory

ACM Transactions on Information and System Security (TISSEC)
Volume 17 Issue 1, August 2014


Users often wish to communicate anonymously on the Internet, for example in group discussion or instant messaging forums. Existing solutions are vulnerable to misbehaving users, however, who may abuse their anonymity to disrupt communication. Dining Cryptographers Networks (DC-nets) leave groups vulnerable to denial-of-service and Sybil attacks, mix networks are difficult to protect against traffic analysis, and accountable voting schemes are unsuited to general anonymous messaging.

DISSENT is the first general protocol offering provable anonymity and accountability for moderate-size groups, while efficiently handling unbalanced communication demands among users. We present an improved and hardened DISSENT protocol, define its precise security properties, and offer rigorous proofs of these properties. The improved protocol systematically addresses the delicate balance between provably hiding the identities of well-behaved users, while provably revealing the identities of disruptive users, a challenging task because many forms of misbehavior are inherently undetectable. The new protocol also addresses several non-trivial attacks on the original DISSENT protocol stemming from subtle design flaws.

Journal version: ACM Digital Library

Extended version: PDF

The work of Ewa Syta, Henry Corrigan-Gibbs, Shu-Chun Weng, David Wolinsky, and Bryan Ford was supported by the Defense Advanced Research Projects Agency (DARPA) and SPAWAR Systems Center Pacific, Contract No. N66001-11-C-4018. Aaron Johnson was supported by DARPA. Any opinions, findings and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of DARPA or SPAWAR.