[Infowarrior] - Make Digital Data Self-Destruct

[Richard Forno]

(Paper being presented @ USENIX -  http://vanish.cs.washington.edu/research.html)


  New Technology to Make Digital Data Self-Destruct

By JOHN MARKOFF
Published: July 20, 2009
http://www.nytimes.com/2009/07/21/science/21crypto.html?_r=1
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.

Public key cryptography makes it possible for two parties who have  
never physically met to share a digital secret and as a result engage  
in a secure electronic conversation sheltered from potential  
eavesdroppers. The technology is at the heart of most modern  
electronic commerce systems.

Vanish uses a key-based encryption system in a different way, making  
it possible for a decrypted message to be automatically re-encrypted  
at a specified point in the future without fear that a third party  
will be able to gain access to the key needed to read the message.

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.

The potential value of such technology was brought into stark relief  
last week when a computer hacker stole data belonging to the social  
media company Twitter and e-mailed it to Web publishing companies in  
the United States and France.

The significance of the advance is that the Vanish “trust model” does  
not depend on the integrity of third parties, as other systems do. The  
researchers cite an incident in which a commercial provider of  
encrypted e-mail services revealed the contents of digital  
communication when served with a subpoena by a Canadian law  
enforcement agency.

The researchers acknowledged that there are unexplored legal issues  
surrounding the use of their technology. For example, certain laws  
require that corporations archive e-mails and make them accessible.

The researchers have developed a prototype of the Vanish system based  
on a plug-in module for the Mozilla Firefox Web browser. Using the  
system requires that both parties of the communication have a copy of  
the module, which is one of the limits of the technology. Mr. Kohno  
said that he did not envision Vanish being used for all  
communications, but only for sensitive ones.