| 摘要 |
A user who wishes to access encrypted data stored on a data carrier, such as a CD or DVD 10, must contact a sewer 50 to request access to the data. If the user is entitled to access the data the sewer will return a decryption key to the user's computer 30 to allow the user to decrypt the data. When the user issues the request to the sewer he may provide registration or/and payment data. The data carrier may also contain unencrypted data such as demonstration audio tracks or video data, allowing the user to try some of the information on the data carrier before paying for access to encrypted content. Preferably the user may access the trial data using standard playback apparatus 20 which has no decryption capability. The data carrier may also contain control data which limits use of the encrypted data to a predetermined number of uses, or a predetermined period of time. There may also be provided means to allow the user to order an additional product related to the encrypted data. |
