Television encryption
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Television encryption, often referred to as "scrambling", is encryption used to control access to pay television services, usually cable or satellite television services.
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[edit] History
Originally, encryption was not used in pay television systems for controlling access to programming. Cable television systems have traditionally relied on controlling access by directly connecting and disconnecting the physical cable that provides programming from the subscriber's home to the actual cable network itself. Satellite television first began using encryption in 1986 when HBO began encrypting its signals.
[edit] Conditional access
[edit] Cable and early satellite television encryption
Analog and digital pay television have several conditional access systems that are used for pay per view (PPV) and other subscriber related services. Originally, analog-only cable TV systems relied on set-top boxes to control access to programming, as television sets originally were not "cable ready". Analog encryption was typically limited to "premium" channels such as HBO or channels with adult-oriented content. In those cases, various proprietary video synchronization suppression algorithms were used to control access to programming. Analog set-top boxes have largely been replaced by digital set-top boxes that can directly control access to programming as well as digitally encrypt signals.
VideoCipher II RS (VCII RS) is the scrambling system that C-Band satellite pay TV channels originally used. A VCII-capable satellite receiver is required to decode VCII channels. VCII has largely been replaced by DigiCipher 2 in North America. Originally, VCII-based receivers had a separate modem technology for pay-per-view access known as Videopal. This technology became fully-integrated in later generation analog satellite television receivers.
- VideoCipher I (deprecated)
- VideoCipher II (deprecated)
- VideoCipher II+
- VideoCipher II RS (Renewable Security)
[edit] Digital cable and satellite television encryption
DigiCipher 2 is Motorola's proprietary video distribution system. DCII is based upon MPEG-2. A 4DTV satellite receiver is required to decode DCII channels. In North America, most digital cable programming is accessed with DigiCipher 2-based set-top boxes.
- DigiCipher II (digital, common usage)
PowerVu is another popular digital encryption technology used for non-residential usage. PowerVu was developed by Scientific Atlanta. Other commercial digital encryption systems are Irdeto (by Irdeto Access), Nagravision (by Kudelski), Viaccess (by France Telecom), and Wegener.
In the United States, both DirecTV and Dish Network direct broadcast satellite systems use digital encryption standards for controlling access to programming. DirecTV uses VideoGuard, a system designed by NDS. DirecTV has been cracked in the past, which led to an abundance of cracked smartcards being available on the black market. However, a switch to a stronger form of smart card (the P4 card) wiped out DirectTV piracy soon after it was introduced. Since then, no public cracks have become available. Dish Network uses Nagravision (1 and 2) encryption.
In Canada, both Bell ExpressVu and StarChoice DBS systems use digital encryption standards. Bell ExpressVu, like Dish Network, uses Nagravision for encryption. StarChoice uses a DigiCipher 2-based system very similar to that of 4DTV large dish satellite systems.
[edit] Older television encryption systems
- Oak Orion
Oak Orion was originally used for analog satellite television pay channel access in Canada. It has been completely replaced by digital encryption technologies.
Leitch (aka Leitch Viewguard) is an analog encryption standard used primarily by broadcast TV networks in the North America. Its method of scrambling is by re-ordering the lines of video, but leaves the audio intact and listenable. Terretrially broadcast CATV systems in Northern Canada (like Sky-UHF in NZ) used this seletive access system for many years. It is only occasionally used today on some satilite circuits because of its similarity to D2-MAC and B-MAC.
B-MAC has not been used for DTH applications since Primestar switched to an all-digital delivery system in the mid-1990s.
- Viewguard
Like VCII, the Viewguard system digitally encrypts video through the use of the cut and rotate method. The audio component of the satellite TV signal also is digitally encrypted.
Smartcard-based cut and rotate scrambling system, used in 1990s by several European satellite broadcasters, mainly British Sky Broadcasting. No audio scrambling.
