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Proceedings on Privacy Enhancing Technologies

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DP5: A Private Presence Service

Nikita Borisov
  • University of Illinois at Urbana-Champaign
  • :
/ George Danezis
  • University College London
  • :
/ Ian Goldberg
  • University of Waterloo
  • :
Published Online: 2015-06-22 | DOI: https://doi.org/10.1515/popets-2015-0008


Users of social applications like to be notified when their friends are online. Typically, this is done by a central server keeping track of who is online and offline, as well as of all of the users’ “buddy lists”, which contain sensitive information. We present DP5, a cryptographic service that implements online presence indication in a privacy-friendly way. DP5 allows clients to register their online presence and query the presence of their list of friends while keeping this list secret. Besides presence, high-integrity status updates are supported, to facilitate key update and rendezvous protocols. While infrastructure services are required for DP5 to operate, they are designed to not require any long-term secrets and provide perfect forward secrecy in case of compromise. We provide security arguments for the indistinguishability properties of the protocol, as well as an evaluation of its scalability and performance.


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Received: 2014-11-15

Revised: 2015-05-15

Accepted: 2015-05-15

Published Online: 2015-06-22

Published in Print: 2015-06-01

Citation Information: Proceedings on Privacy Enhancing Technologies. Volume 2015, Issue 2, Pages 4–24, ISSN (Online) 2299-0984, DOI: https://doi.org/10.1515/popets-2015-0008, June 2015

© Nikita Borisov et al.. This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License. (CC BY-NC-ND 3.0)

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