A group of University of Washington students and professors has developed an application called Vanish that automatically makes data used with it disappear after eight to nine hours.

The open-source software is downloadable now, as well as information about how to use it and a research paper about its development, which will be presented at USENIX next month.

Using the system requires that users encrypt their data, meaning it is only for certain data, not for everything. Currently, it works with Firefox. Any text application, including Web-based e-mail such as Hotmail, Yahoo and Gmail, Web chat, or the social networking sites MySpace and Facebook, can work with Vanish. Researchers said the same technique could work for any type of data, such as digital photos.

The software works by using a key to encrypt the data, which none of the recipients possess, and storing the key in pieces in various places on the network. "As machines constantly join and leave the P2P network, the pieces of the key gradually disappear," the group explains. "By the time the hacker or someone with a subpoena actually tries to obtain access to the message, the pieces of the key will have permanently disappeared."

It is also possible to set up the system to keep data for multiple eight-hour periods.

The group notes that the system is a research prototype only, and that certain legal requirements -- such as having corporate or government documents accessible -- may preclude its use.

Encryption has traditionally come under some government attack in the U.S. -- where it at one point was classified as a munition, and PGP developer Phil Zimmerman was investigated -- and it is not clear how the government feels about Vanish.