I'll lose a few minutes less sleep each night worrying about Electronic Eternity – thanks to the serendipitous appearance of John Markoff's recent piece on Vanish in the New York Times Science section:
A group of computer scientists at the University of Washington has developed a way to make electronic messages “self destruct” after a certain period of time, like messages in sand lost to the surf. The researchers said they think the new software, called Vanish, which requires encrypting messages, will be needed more and more as personal and business information is stored not on personal computers, but on centralized machines, or servers. In the term of the moment this is called cloud computing, and the cloud consists of the data — including e-mail and Web-based documents and calendars — stored on numerous servers.
The idea of developing technology to make digital data disappear after a specified period of time is not new. A number of services that perform this function exist on the World Wide Web, and some electronic devices like FLASH memory chips have added this capability for protecting stored data by automatically erasing it after a specified period of time.
But the researchers said they had struck upon a unique approach that relies on “shattering” an encryption key that is held by neither party in an e-mail exchange but is widely scattered across a peer-to-peer file sharing system…
The pieces of the key, small numbers, tend to “erode” over time as they gradually fall out of use. To make keys erode, or timeout, Vanish takes advantage of the structure of a peer-to-peer file system. Such networks are based on millions of personal computers whose Internet addresses change as they come and go from the network. This would make it exceedingly difficult for an eavesdropper or spy to reassemble the pieces of the key because the key is never held in a single location. The Vanish technology is applicable to more than just e-mail or other electronic messages. Tadayoshi Kohno, a University of Washington assistant professor who is one of Vanish’s designers, said Vanish makes it possible to control the “lifetime” of any type of data stored in the cloud, including information on Facebook, Google documents or blogs. In addition to Mr. Kohno, the authors of the paper, “Vanish: Increasing Data Privacy with Self-Destructing Data,” include Roxana Geambasu, Amit A. Levy and Henry M. Levy.