Check out the new USENIX Web site.
USENIX, The Advanced Computing Systems Association

5th USENIX Conference on File and Storage Technologies Abstract

Pp. 231244 of the Proceedings

Cobalt: Separating Content Distribution from Authorization in Distributed File Systems

Kaushik Veeraraghavan, Andrew Myrick, and Jason Flinn, University of Michigan


How should a distributed file system manage access to protected content? On one hand, distributed storage should make data access pervasive: authorized users should be able to access their data from any location. On the other hand, content protection is designed to restrict access this is often accomplished by limiting the set of computers from which content can be accessed. In this paper, we propose a new method for storing content in distributed storage called Cobalt. Rather than grant access to data based on the computer that reads the data, Cobalt grants access based on the physical proximity of authorized users. Protected content is stored encrypted in the distributed Blue File System; files can only be decrypted through the cooperation of a personal, mobile device such as cell phone. The Cobalt device is verified by content providers: it acts as a proxy that protects their interests by only decrypting data when policies specified during content acquisition are satisfied. Wireless communication with the device is used to determine the physical proximity of its user; when the Cobalt device moves out of range, protected content is made inaccessible. Our results show that Cobalt adds only modest overhead to content acquisition and playback, yet it enables new forms of interaction such as the ability to access protected content on ad hoc media players and create playlists that adapt to the tastes of nearby users.
  • VView the full text of this paper in HTML and PDF. Listen to the presentation in MP3 format.
    Click here if you have forgotten your password Until February 2008, you will need your USENIX membership identification in order to access the full papers. The Proceedings are published as a collective work, 2007 by the USENIX Association. All Rights Reserved. Rights to individual papers remain with the author or the author's employer. Permission is granted for the noncommercial reproduction of the complete work for educational or research purposes. USENIX acknowledges all trademarks within this paper.
To become a USENIX member, please see our Membership Information.

Last changed: 4 May 2007 ac