A Revocable Backup System

Abstract:

We present a system which enables a user to remove a file from both
the file system and all the backup tapes on which the file is stored.
The ability to remove files from all backup tapes is desirable in
many cases. Our system erases information from the backup tape without
actually writing on the tape. This is achieved by applying cryptography in
a new way: a block cipher is used to enable the system to ``forget''
information rather than protect it. Our system is easy to install
and is transparent to the end user. Further, it introduces no slowdown
in system performance and little slowdown in the backup procedure.

This technical report has been published as

A Revocable Backup System. Dan Boneh and Richard J. Lipton,
6th USENIX Security Symposium, July 22-25, 1996,
San Jose, CA, pp. 91-96.