Television encryption, often referred to as scrambling, is encryption used to control access to pay television services, usually cable, satellite, or Internet Protocol television (IPTV) services.
History Pay television exists to make revenue from subscribers, and sometimes those subscribers do not pay. The prevention of piracy on cable and satellite networks has been one of the main factors in the development of Pay TV encryption systems. The early cable-based Pay TV networks used no security. This led to problems with people connecting to the network without paying. Consequently, some methods were developed to frustrate these self-connectors. The early Pay TV systems for cable television were based on a number of simple measures. The most common of these was a channel-based filter that would effectively stop the channel being received by those who had not subscribed. These filters would be added or removed according to the subscription. As the number of television channels on these cable networks grew, the filter-based approach became increasingly impractical. Other techniques, such as adding an interfering signal to the video or audio, began to be used as the simple filter solutions were easily bypassed. As the technology evolved, addressable set-top boxes became common, and more complex scrambling techniques such as digital encryption of the audio or video cut and rotate (where a line of video is cut at a particular point and the two parts are then reordered around this point) were applied to signals. Encryption was used to protect satellite-distributed feeds for cable television networks. Some of the systems used for cable feed distribution were expensive. As the DTH market grew, less secure systems began to be used. Many of these systems (such as Oak Orion) were variants of cable television scrambling systems that affected the synchronisation part of the video, inverted the video signal, or added an interfering frequency to the video. All of these analogue scrambling techniques were easily defeated. In France, Canal+ launched a scrambled service in 1984. It was also claimed that it was an unbreakable system. Unfortunately for that company, an electronics magazine, "Radio Plans", published a design for a pirate decoder within a month of the channel launching. In the US, HBO was one of the first services to encrypt its signal using the VideoCipher II system. In Europe, FilmNet scrambled its satellite service in September 1986, thus creating one of the biggest markets for pirate satellite TV decoders in the world, because the system that FilmNet used was easily hacked. One of FilmNet's main attractions was that it would screen hard-core porn films on various nights of the week. The VideoCipher II system proved somewhat more difficult to hack, but it eventually fell prey to the pirates.
Conditional access
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 television 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 methods were used to control access to programming. In some of these systems, the necessary sync signal was on a separate subcarrier though sometimes the sync polarity is simply inverted, in which case, if used in conjunction with PAL, a SECAM L TV with a cable tuner can be used to partially descramble the signal though only in black and white and with inverted luminance and thus a multi standard TV which supports PAL L is preferred to decode the color as well. This, however will lead to a part of the video signal being received as audio as well and thus another TV with preferably no auto mute should be used for audio decoding. Analog set-top boxes have largely been replaced by digital set-top boxes that can directly control access to programming as well as digitally decrypt signals. Although several analog encryption types were tested in the early 1980s, VideoCipher II became the de facto analog encryption standard that C-Band satellite pay TV channels used. Early adopters of VCII were HBO and Cinemax, encrypting full time beginning in January 1986; Showtime and The Movie Channel beginning in May 1986; and CNN and Headline news, in July of that year. VideoCipher II was replaced as a standard by VCII+ in the early 1990s, and it in turn was replaced by VCII+ RS. 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)
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