A conditional access system (CAS) is a system by which electronic transmission of digital media, especially satellite television signals through cable, is limited to subscribed clients. This is called conditional access. The signal is encrypted and is unavailable for unauthorised reception. A set-top box containing a conditional access module is required in the customer premises to receive and decrypt the signal.
CAS is now becoming a significant concern for major companies in the DVB-H market because broadcasters are looking to control the digital signals that they will be broadcasting.
