M/A-COM - The Videocipher 2 Decoder
The VideoCipher II has the following features:
Video Encryption - Simply done my inverting the polarity of the video signal and moving the
color burst to a nonstandard position on the waveform.
An 88-Bit data stream and a color burst at 3.58 MHz instead of a synch pulse is inserted in
the waveform. There is no 4.5MHz sound carrier needed.
The 88 bits of data are used for the 2 digital audio channels, billing data, synch data, program control, and can also be used as an auxilary data channel.
The 88-bit data stream contains (DES) Data Encryption Standard audio data. The two audio channels are filtered and digitized. Each of the digital samples has a random binary sequence and contains error-coding bits which are generated by the DES algorithm.
The appearance of these audio bits appear random.
The DES keys used are 72 quadrillion in number, thus a multilevel key organization and distribution method must be utilized. Each descrambler has it's own address (User ID) and a number of DES keys.
To authorize scrambled channels for a certain period of time such as monthly or an annual subscription the descrambler must receive the authorization data from the satellite which contains the monthly key and status of the service purchased also known as tiering.
This data is sent over the control channel to the descrambler and is encrypted with the descrambler's key. Since the descramblers key is sent no other descrambler will use this data. All other descramblers will ignore this data, only the one with the correct key
will use the incoming data. Each program is encrypted with it's own key. This key is combined with the billing information of the program, the rating, the program tiering, and the monthly key, all this is transmitted across the control channel. Only descramblers
containing the current monthly key will be authorized to receive this program, all others will remain turned off.
A total of 600,000 descramblers can be addressed per hour. Fifty-seix tiers of programming can be used in any combination. The tier feature can also be used to 'blackout' certain programs in various areas simpy by placing the programs in tiers and not authorizing
the descramblers in those areas in which the program is to be blacked out. Programs which use the rating system can also be tiered and then blacked out which could prevent unathorized viewing by children.
The VCII data stream also carries dual language audio capabilities as well as Teletext and personal messaging. The messaging usually consists of advertisement of big events or subscription reminders and specials.
The VCII system was used widely in the satellite industry for many years but has been replaced with the VCRS for security reasons. The VCII descrambler is still used in some headend cable systems and are still actively running. All consumer based VCII descramblers have been
disabled.
Pictured below is an old "rack mount" commercial vc2 descrambler. It measures 19 x 7 x 10 and
for video connections uses standard BNC connections.
Pictured above is the newest versions of videocipher modules avalable to the CONSUMER.
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