Disable unauthorized copying.
Content copy protection in consumer HDTV has another layer of protection previously unavailable in the SD world.
HDCP system scrambles the high definition signal between devices such as HDTV cable box and the monitor. Each device in the chain must be capable to “speak” the same encryption language. If a recording device such as a recordable HD DVD is introduced in the chain it also has to be able to decrypt the signal in order to perform the recording.
In case the device can not decrypt the signal HDCP protocol is intelligent enough to allow the downstream device to receive standard definition downconversion of the signal.