A media playback system where data is decrypted subject to certain access conditions being met

摘要

The invention relates to the conditional decoding of encoded data by use of a decoding device which determines the conditions under which decoding may take place. The data may be distributed as CD-ROM, magnetic disc etc or downloaded. The access terms may be distributed with the data or may be transmitted separately. The access limitations may include playback at certain times, a limited number of playback events, a payment requirement, the playback of other data such as advertisement or the acceptance of a service such as direct mail. Copying of the data may also be controlled.