CA modules (CAMS)
A conditional access module (CAM) is a device used to encrypt and decrypt digital signals transmitted over a TV network. CAM modules, sometimes simply described as CA modules, are usually used in TV receivers that must be able to receive and play digital TV channels that require some form of paid subscription to view them. When a user subscribes to a channel, the CAM module will encrypt the signal from the channel so that it can only be decrypted by a TV receiver with the right subscription. In this way, TV providers can ensure that only paying users have access to their channels.
An encrypted CAM signal can be decoded by using a TV receiver equipped with a matching CAM module. When the receiver receives an encrypted signal from a TV channel, the CAM module in the receiver will decrypt the signal so that it can be displayed on the TV screen. For this to happen, the TV receiver must be equipped with the right CAM module and have the right subscription to the channel. If the TV receiver does not have the correct CAM module or subscription, the signal will remain encrypted and cannot be decoded.
Different forms of CAM encryption exist, depending on the system used to encrypt and decrypt digital TV signals. Some of the most common forms of CAM encryption include: Conax, Nagravision, Cryptoworks, Irdeto, Viaccess, Biss, PowerVu, Mediaguard, Nagra, Biss-E and Verimatrix.
Encryption is used by some TV providers. It is an advanced form of encryption that makes it difficult for unauthorized persons to decode digital TV signals unless you have the correct module and subscription.