DigiCipher 2, or simply DCII, is a proprietary standard format of digital signal transmission and it doubles as an

encryption In Cryptography law, cryptography, encryption (more specifically, Code, encoding) is the process of transforming information in a way that, ideally, only authorized parties can decode. This process converts the original representation of the inf ...

standard with MPEG-2/MPEG-4 signal

video compression In information theory, data compression, source coding, or bit-rate reduction is the process of encoding information using fewer bits than the original representation. Any particular compression is either lossy or lossless. Lossless compression ...

used on many

communications satellite A communications satellite is an artificial satellite that relays and amplifies radio telecommunication signals via a Transponder (satellite communications), transponder; it creates a communication channel between a source transmitter and a Rad ...

television Television (TV) is a telecommunication medium for transmitting moving images and sound. Additionally, the term can refer to a physical television set rather than the medium of transmission. Television is a mass medium for advertising, ...

and audio signals. The DCII standard was originally developed in 1997 by General Instrument, which then became the Home and Network Mobility division of

Motorola Motorola, Inc. () was an American multinational telecommunications company based in Schaumburg, Illinois. It was founded by brothers Paul and Joseph Galvin in 1928 and had been named Motorola since 1947. Many of Motorola's products had been ...

, then bought by

Google Google LLC (, ) is an American multinational corporation and technology company focusing on online advertising, search engine technology, cloud computing, computer software, quantum computing, e-commerce, consumer electronics, and artificial ...

in Aug 2011, and lastly became the Home portion of the division to Arris. The original attempt for a North American digital signal encryption and compression standard was DigiCipher 1, which was used most notably in the now-defunct

PrimeStar PrimeStar was an American direct broadcast satellite broadcasting company formed in November 1990 by seven cable television companies including Comcast Corp. and TCI Communications Corp. PrimeStar was the first medium-powered DBS system in the U ...

medium-power

direct broadcast satellite Satellite television is a service that delivers television programming to viewers by relaying it from a communications satellite orbiting the Earth directly to the viewer's location.ITU Radio Regulations, Section IV. Radio Stations and Systems ...

(DBS) system during the early 1990s. The DCII standard predates wide acceptance of DVB-based digital terrestrial television compression (although not cable or satellite DVB) and therefore is incompatible with the DVB standard. Approximately 70% of newer first-generation

digital cable Digital cable is the distribution of cable television using digital data and video compression. The technology was first developed by General Instrument. By 2000, most cable companies offered digital features, eventually replacing their previo ...

networks in North America use the

4DTV 4DTV is a proprietary broadcasting standard and technology for digital cable broadcasting and C-band/Ku-band satellite dishes from Motorola, using General Instrument's DigiCipher II for encryption. It can tune in both analog VideoCipher II and ...

/DigiCipher 2 format. The use of DCII is most prevalent in North American digital

cable television Cable television is a system of delivering television programming to consumers via radio frequency (RF) signals transmitted through coaxial cables, or in more recent systems, light pulses through fibre-optic cables. This contrasts with bro ...

set-top box A set-top box (STB), also known as a cable converter box, cable box, receiver, or simply box, and historically television decoder or a converter, is an information appliance device that generally contains a Tuner (radio)#Television, TV tuner inpu ...

es. DCII is also used on Motorola's 4DTV digital

satellite television Satellite television is a service that delivers television programming to viewers by relaying it from a communications satellite orbiting the Earth directly to the viewer's location.ITU Radio Regulations, Section IV. Radio Stations and Systems ...

tuner and

Shaw Direct Shaw Direct G.P. is a direct broadcast satellite television distributor in Canada and a subsidiary of the telecommunications company Rogers Communications. As of 2010, Shaw Direct had over 900,000 subscribers. It broadcasts on Ku band from two ...

's DBS receiver. The DigiCipher 2 encryption standard was reverse engineered in 2016.

Technical specifications

DigiCipher II uses QPSK and BPSK at the same time. The primary difference between DigiCipher 2 and DVB lies in how each standard handles SI

metadata Metadata (or metainformation) is "data that provides information about other data", but not the content of the data itself, such as the text of a message or the image itself. There are many distinct types of metadata, including: * Descriptive ...

, or System Information, where DVB reserves packet identifiers from 16 to 31 for metadata, DigiCipher reserves only packet identifier 8187 for its master guide table which acts as a ''look-up table'' for all other metadata tables. DigiCipher 2 also extends the MPEG ''program number'' that is assigned for each service in a transport stream with the concept of a

virtual channel In most telecommunications organizations, a virtual channel is a method of remapping the ''program number'' as used in H.222 Program Association Tables and Program Mapping Tables to a channel number that can be entered as digits on a receiver's ...

number, whereas the DVB system never defined this type of remapping preferring to use a registry of ''network'' identifiers to further differentiate ''program numbers'' from those used in other transport streams. There are also private non-standard additions to DVB that add virtual channel remapping using ''logical channel numbers''. Also unlike DVB, all text used in descriptors can be compressed using standard

Huffman coding In computer science and information theory, a Huffman code is a particular type of optimal prefix code that is commonly used for lossless data compression. The process of finding or using such a code is Huffman coding, an algorithm developed by ...

which saves on broadcast bandwidth and loading times. DigiCipher II uses Dolby Digital AC-3 audio for all channels, although MPEG-1 Level 2 audio is not supported.

External links

Technical page on digital satellite signalsHistorical Perspective: HBO Implements Scrambling

References

{{broadcast encryption Cryptographic protocols Digital television Television terminology Conditional-access television broadcasting Digital rights management systems 1997 introductions Telecommunications-related introductions in 1997 Audiovisual introductions in 1997