One of the main attributes of traditional (legacy) broadcasting is that it is a one-way distribution system. Under this system, the satellite or cable feed is distributed to everyone, and the transmitting organization does not receive any feedback regarding who is picking up their feed or what they are doing with it.
The STB, which integrates a specific conditional access system, has the technology from the conditional access system provider to decrypt the feed but needs the specific encryption key from the broadcaster to do so, together with an entitlement that confirms the user may decrypt this content.
The CAS uses the EMM to specify a user’s unique entitlement (such as the channels paid for) to enable the decryption of the signal. In the same way, if a user fails to pay their bill or drops a channel from their package, it will remain encrypted and not available for watching.
