BISS

Basic Interoperable Scrambling System, usually known as BISS, is a satellite signal scrambling system developed by the European Broadcasting Union and a consortium of hardware manufacturers.

Prior to its development, "ad-hoc" or "Occasional Use" satellite news feeds were transmitted without any encryption. This allowed anyone with the correct equipment to view the program material. Using BISS the transmission is protected by a 12 digit "session key" that is agreed by the transmitting and receiving parties prior to transmission. The key is entered into both the encoder and decoder , this key then forms part of the encryption of the digital TV signal and only receivers with the correct key will decrypt the signal.