Opinion ID: 787794
Heading Depth: 2
Heading Rank: 5

Heading: The Accused DISH Network System

Text: 31 In the accused DISH Network system, digital television signals are encrypted and decrypted using a key called a Control Word. The district court found, and the parties do not dispute, that Control Words correspond to the service keys in claim 1(a). The DISH Network changes Control Words very frequently. Changes in Control Words are, in turn, communicated through Entitlement Control Messages or ECMs — encrypted using the so-called Transmission Key — broadcast to all active receivers within the system. As the district court found, and as the parties do not dispute, the Transmission Key is shared by all subscribers within the DISH Network system. It is also undisputed that the accused system has no key associated with groups organized by viewer programming preference, geographic area, or any other subset of the total DISH Network subscriber base, that is used to encipher messages communicating new Control Words.