SWS   Info

Expert Audience

English

60 Minutes

Saarbrücken

The ability to participate anonymously in online communities is widely valued, but existing anonymous communication protocols offer limited security against anonymous abuse, traffic analysis, or denial-of-service attacks. Dissent is a general-purpose anonymous messaging protocol that addresses these limitations in the context of group communication applications, where members of a well-defined group wish to "post" messages anonymously to each other or onto a common "bulletin board" without a message being linkable to a particular group member. Unlike most existing anonymous communication schemes, the Dissent protocol provides anonymity while also holding its members accountable: if a group member deviates from the protocol in attempt to block communication or attack other members anonymously, the protocol ensures that the group can identify and expel the misbehaving member. The key technical idea enabling this combination of anonymity and accountability is to use a verifiable cryptographic shuffle scheme as a setup phase for a dining cryptographers (DC-nets) communication channel. The verifiable shuffle enables the group to create and agree on a random permutation of user identities to pseudonyms, then use that permutation as a logical schedule for subsequent DC-nets communication. The group can use this agreed-upon schedule to identify any member attempting to disrupt communication by deviating from the schedule or jamming the DC-nets channel. Currently working prototypes of Dissent support small groups, but ongoing efforts are extending the protocol to scale to large groups, handle node failure and network churn gracefully, and address intersection attacks against users who maintain long-term pseudonyms

Brigitta Hansen

0681 93039102

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Yes

Kaiserslautern

G26

206

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