Cryptagram: Photo privacy for online social media

Matt Tierney, Ian Spiro, Christoph Bregler, Lakshminarayanan Subramanian

Research output: Chapter in Book/Report/Conference proceedingConference contribution


While Online Social Networks (OSNs) enable users to share photos easily, they also expose users to several privacy threats from both the OSNs and external entities. The current privacy controls on OSNs are far from adequate, resulting in inappropriate flows of information when users fail to understand their privacy settings or OSNs fail to implement policies correctly. OSNs may further complicate privacy expectations when they reserve the right to analyze uploaded photos using automated face identification techniques. In this paper, we propose the design, implementation and evaluation of Cryptagram, a system designed to enhance online photo privacy. Cryptagram enables users to convert photos into encrypted images, which the users upload to OSNs. Users directly manage access control to those photos via shared keys that are independent of OSNs or other third parties. OSNs apply standard image transformations (JPEG compression) to all uploaded images so Cryptagram provides an image encoding and encryption mechanism that is tolerant to these transformations. Cryptagram guarantees that the recipient with the right credentials can completely retrieve the original image from the transformed version of the uploaded encrypted image while the OSN cannot infer the original image. Cryptagram's browser extension integrates seamlessly with preexisting OSNs, including Facebook and Google+, and currently has over 400 active users.

Original languageEnglish (US)
Title of host publicationCOSN 2013 - Proceedings of the 2013 Conference on Online Social Networks
PublisherAssociation for Computing Machinery
Number of pages13
ISBN (Print)9781450320849
StatePublished - 2013
Event1st ACM Conference on Online Social Networks, COSN 2013 - Boston, MA, United States
Duration: Oct 7 2013Oct 8 2013

Publication series

NameCOSN 2013 - Proceedings of the 2013 Conference on Online Social Networks


Other1st ACM Conference on Online Social Networks, COSN 2013
Country/TerritoryUnited States
CityBoston, MA


  • online social media
  • photo privacy

ASJC Scopus subject areas

  • Computer Networks and Communications


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