| 摘要 |
A system that provides secure transmission and complete access control for target devices. Such a system includes a distribution center, a video-on-demand system, a transmission network and a plurality of target devices. The video-on-demand system advantageously provides for encryption of the transmission, transmission of access keys, and access control. The target devices also include circuitry for communicating with the video server and decrypting the transmission and controlling access to video services. A method for providing conditional access to video services for a plurality of subscriber stations comprises the steps of: authorizing the plurality of subscriber stations to receive the video services; receiving a first order for a first video service from a first subscriber station; and transmitting tuning data to the first subscriber station so that the first subscriber station is able to receive the first video service. The method may also prevent the theft of the content of transmissions by performing the steps of: scrambling the first video service using a first key to generate a first scrambled video service; scrambling the first key using decryption data to generate a first scrambled key; distributing the decryption data to decrypt the first scrambled key to the plurality of subscriber stations; transmitting the first scrambled video service to the plurality of subscriber stations; and transmitting the first scrambled key to the plurality of subscriber stations. |
