Researchers at the University of Washington have developed software that will automatically delete files like emails within a pre-set time limit.

The Vanish software allows the user of any web-based service to encrypt a message, but instead of the user keeping the key, it is put into a global peer-to-peer (P2P) network for a specified time before disappearing, making it impossible to decrypt the message.

"Today many people pick up the phone when they want to talk with a lawyer or have a private conversation. But more and more communication is happening online," said Washington computer scientist Tadayoshi Kohno.

"Vanish is designed to give people the same privacy for email and the web that they expect for a phone conversation."

The system uses the Vuze BitTorrent Distributed Hash Table as its P2P network, and currently sets default time limits on messages at eight hours, although longer periods should be possible.

The team is now developing a Firefox application that integrates Vanish for general use.

"In today's world, private information is scattered all over the internet, and we cannot control the lifetime of that data," said team member Hank Levy.

"And as we transition to a future based on cloud computing, where enormous, anonymous datacentres run the vast majority of our applications and store nearly all of our data, we will lose even more control."

The team will present its full paper on the system next month at Usenix Security '09 in Montreal.