US Patent 7559088 Method and apparatus for deleting data upon expiration

A method and apparatus for efficiently deleting data including backup or snapshots upon expiration are disclosed. The data can be deleted even without physical access to the data. A data generation unit generates a data. Each data has an expiration time and should be deleted upon expiration. An encryption unit encrypts the data, and the encrypted data is stored in data storage. A controller monitors whether there is an expired data, and if there is an expired data, the controller deletes a key necessary for decrypting the expired data.