Data delivery method and data delivery system

摘要

A data delivery system highly resistant to misappropriation of data. A plurality of pieces of key information are generated on the basis of an encryption key specific to each digital data item to be delivered. The multiple pieces of key information are delivered over routes which differ from the routes used to deliver the digital data and which further differ from each other. Physically different media or transmission over a network at different times are used to transmit the different sets of key information separately.