Adnostic: Privacy Preserving Targeted Advertising

Privacy and Security, Networks, the Internet, and Cloud Computing, Internet and Search and Advertising

Article Snapshot


Solon Barocas, Dan Boneh, Arvind Narayanan, Helen Nissenbaum and Vincent Toubiana


Proceedings of the Network and Distributed Systems Symposium, March 2010


By operating within a user’s browser, Adnostic respects user privacy and supports online behavioral advertising.

Policy Relevance

Legislators should recognize that technical solutions simultaneously safeguarding online user privacy and empowering legitimate commerce are both possible and desirable.

Main Points

  • Online behavioral advertising, which uses web cookies to track the browsing habits of users and tailors online advertisements accordingly, has prompted concerns about invasions of privacy. However, targeted advertising online need not run afoul of a user’s privacy by using Adnostic, a web application and browser plugin that selects ads based on the stored contents of a browser’s history and communicates user preferences to third party advertisers through encrypted channels that preserve the user’s privacy.
  • Existing online behavioral tracking systems allow online ad network companies to record user behavior in order to place advertisements within particular websites based on the user’s browsing history, the content of the site itself, or information regarding previous advertisements a particular user has clicked on.
  • Adnostic limits an ad network’s access to data about a user’s clickstream, behavioral profile, and ad impression history, while sharing a user’s ad click history.
  • Adnostic is designed to both improve user privacy and ad network efficiency: all behavioral analysis is performed within a user’s own browser, so a comprehensive encrypted profile of user preferences can be accumulated by Adnostic without sacrificing user privacy. Adnostic then signals to ad networks which sorts of ads to provide without revealing the substance of analysis to the ad network.
  • Several objections to a system such as Adnostic are possible: that it uses considerable network bandwidth, may not provide the same degree of behavioral granularity as current ad networks, and relies on ad networks to abide by its technical restrictions.

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