Academic researchers at a US university have developed software that puts a time limit on text uploaded to any web service through a standard web browser, after which the text will self erase.

Dubbed Vanish, the free and open-source system being prototyped by the University of Washington will work with the Firefox browser and lets users erase data after any multiple of eight hours.

The system is based on a type of encryption. For each message that it sends, Vanish reportedly creates a secret key, which is never revealed to the user, and then encrypts the message with that key.

Pieces of the key are dispersed at random onto computers that belong worldwide file-sharing peer-to-peer networks.

Over time parts of the key become permanently inaccessible. Once enough key parts are lost, the original e-mail, Facebook post or chat message can no longer be deciphered.