New Technology to Make Digital Data Self-Destruct
New York Times (07/20/09) Markoff, John

University of Washington computer scientists have developed software that enables electronic documents to automatically destroy themselves after a certain period of time. The researchers say the software, dubbed Vanish, will be needed as an increasing number of personal and business documents are moved from being stored on personal computers to centralized machines or servers as the cloud computing trend grows. The concept of having digital information disappear after a period of time is not new, but the researchers say they have developed a unique approach that relies on "shattering" an encryption key that is widely distributed across a peer-to-peer file sharing system. Vanish uses a key-based encryption system in a new way, allowing for a decrypted message to be automatically re-encrypted at a specific point in the future without fear that a third party will be able to access the key needed to read the message. The researchers say that pieces of the key "erode" over time as they are gradually used less and less. To make the keys erode, Vanish uses the structure of peer-to-peer file systems, which are based on millions of personal computers that join and leave the network at will, creating frequently changing Internet addresses, making it incredibly difficult for an eavesdropper to reassemble the key because it is never held in a single location. A major advantage of Vanish is that it does not rely on the integrity of third parties, as other systems do.