Nagravision (or Nagra Kudelski or simply Nagra) is a company of the Kudelski Group that develops conditional access systems for digital cable and satellite television. The name is also used for their main products, the Nagravision encryption systems.
An analog Nagravision system (Syster) for scrambling analog satellite television programs was used in the 1990s. In this line-shuffling system, bottom 32 lines of the PAL TV signal are shifted in time by one video field, and read out in permuted order under the control of a pseudorandom number generator. A smartcard security microcontroller (in a key-shaped package) decrypts data that is transmitted during the blanking intervals of the TV signal mixed with teletext and extracts the random seed value which contains present line combination needed for reverting the picture back. The system also permitted the audio signal to be modulated at 12.8 kHz using a frequency mixer.
4 currently used versions of Nagravision are in common use for digital satellite television, known as Nagravision, Nagravision Cardmagedon, Nagravision Aladin and Nagravision Merlin. Nagravision Cardmagedon and Aladin are often confused with each other and used under the term "Nagravision 2" which technically does not exist. Nagravision Cardmagedon is, however, a complicated combination of Nagravision Aladin and Mediaguard SECA 2 encryption. Nagravision Merlin is also known as Nagravision 3.
The decryption unit is either integrated into a receiver, available as a conditional-access module (CAM), or as one of many encryption schemes supported on a CAM emulator.
Nagravision has been adopted all over the world as a conditional access system, with providers: