Privacy Preserving Web-Based Email

  • Kevin Butler
  • William Enck
  • Jennifer Plasterr
  • Patrick Traynor
  • Patrick McDaniel
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 4332)


Recent web-based applications offer users free service in exchange for access to personal communication, such as on-line email services and instant messaging. The inspection and retention of user communication is generally intended to enable targeted marketing. However, unless specifically stated otherwise by the collecting service’s privacy policy, such records have an indefinite lifetime and may be later used or sold without restriction. In this paper, we show that it is possible to protect a user’s privacy from these risks by exploiting mutually oblivious, competing communication channels. We create virtual channels over online services (e.g., Google’s Gmail, Microsoft’s Hotmail) through which messages and cryptographic keys are delivered. The message recipient uses a shared secret to identify the shares and ultimately recover the original plaintext. In so doing, we create a wired “spread-spectrum” mechanism for protecting the privacy of web-based communication. We discuss the design and implementation of our open-source Java applet, Aquinas, and consider ways that the myriad of communication channels present on the Internet can be exploited to preserve privacy.


Virtual Channel Message Authentication Code Covert Channel Application Provider Email Account 


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Copyright information

© Springer-Verlag Berlin Heidelberg 2006

Authors and Affiliations

  • Kevin Butler
    • 1
  • William Enck
    • 1
  • Jennifer Plasterr
    • 1
  • Patrick Traynor
    • 1
  • Patrick McDaniel
    • 1
  1. 1.Systems and Internet Infrastructure Security LaboratoryThe Pennsylvania State UniversityUSA

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