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VideoGuard

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VideoGuard (sometimes referred to simply as NDS), produced by NDS, is a digital encryption system for use with conditional access television broadcasting. It is used almost exclusively on digital satellite television systems operated by News Corporation, which owns the majority of NDS. Its two most widely used implementations are BSkyB's Sky Digital in the United Kingdom and Ireland and DirecTV in the United States, the former of which adopted the system in 1998. Several other broadcasters around the world use the VideoGuard system, including Hot (Israel), Yes (Israel), Viasat (Scandinavia), SKY Italia (Italy), Sky Network Television (New Zealand), Foxtel (Australia), Tata Sky & Hathway (DVB-C) (India), D Smart (Turkey), TotalTV (Serbia), ONO (Spain), Canadian Broadcasting Corporation (Canada), China Central Television (China) and Telewizja Polska (Poland).

Since the majority of content provided by companies like BSkyB requires subscription, VideoGuard protects that content by encrypting both standard subscription channels and pay-per-view movies and events. Access flags can be downloaded to the subscriber's card either over the air (via 'hidden' data streams) or by using the box's built in modem, thereby allowing rapid changing of channel packages and ordering of events.

The VideoGuard system was introduced by News Corporation to replace the analogue VideoCrypt system. To date, the current encryption method has remained secure, although various pay per view flaws have been identified. Even these flaws are related merely to the circuitry of the Set-Top Box (STB), rather than the NDS card. It is suspected that the version initially used by Sky Digital was either insecure or close to being broken, as a software update rolled out to all boxes required replacement of the BSkyB subscriber's viewing card.

Despite being designed to protect pay-TV, VideoGuard was used by BSkyB to encrypt Five and its spin off channels (Five US, Fiver and the +1 versions) to prevent these channels being viewed outside the UK for copyright reasons[citation needed]. However, Five now appears on FreeSat and no longer requires decryption. Currently, the rest of the Five group remain encrypted, may be because of contractual reasons between them and Sky. Before July 2008 Channel 4 used VideoGuard to encrypt all its channels, it made a version of Channel 4 and its More 4 and E4 channels Free to Air (FTA) in April/May 2008 to make them available on the recent Freesat platform which does not have VideoGuard (or any encryption system), August 2008 all versions of Channel 4 (except ROI) are now FTA. Similarly until November 2005 all of ITV's channels were also encrypted using VideoGuard, but switched to becoming unencrypted like the BBC's channels[citation needed]. Before July 10th 2008 the BBC Channels were also encrypted in VideoGuard. All these channels can also be viewed using the Freesat from Sky product which, due to the availability of inexpensive cards, potentially increases the risk of VideoGuard becoming cracked through experimentation[dubious – discuss].

To greatly improve[citation needed] security of the Videoguard encryption, News Corporation's encrypted output can be viewed only using a designated STB in which VideoGuard is embedded into the circuitry.This is not strictly true you can get a CAM module for some satellite receivers that will unscramble NDS be it with a valid sky subscription! (NDS have actually produced a CAM module which is used within Scandinavia, and can be used in any Third party STB). In contrast, CAMs and even software CAMs are available for all other encryption systems, including Irdeto, Nagravision and Viaccess. The CAM monopoly may be broken due to Italian inter-operability laws, which are forcing Sky Italia to allow other boxes to read their cards for legally acquired services.

Several groups managed to reverse-engineer VideoGuard to the point where a legitimate subscriber's card can be read and utilised firmware to decrypt only those channels that subscriber is authorised to view. A software CAM emulator exists for the DreamBox & Triple-Dragon Linux-powered satellite receivers, along with the Diablo, Dragon and T-Rex Conditional Access modules. However, many broadcasters choose to pair their cards to a specific STB serial number, meaning that a paired (also called "married") card can be used only in a broadcaster-supplied STB, or by using the serial number from said receiver with one of the reverse-engineered solutions. In the case of Sky Digital, cards with a "premium" subscription (ie Sports or Movies packages) are paired. Cards that decrypt only Free to View (FTV) channels (e.g. Five) or basic subscription "mixes" are not necessarily paired. None of the reverse-engineered solutions are able to "update" the card, meaning the legitimate card needs to be in an official Sky receiver for a few minutes to get the update when the last update has expired. Every update lasts only a few weeks.[citation needed]

Currently the Dreambox CCcam emulator will allow updates to be written to a valid NDS card.[citation needed]

The new Darkbox HD has now been tested with official Sky cards and has been found to work with them.[citation needed]

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