Common Interface

Various components of Conditional Access

Common Interface scheme

DVB-Receiver with Common Interface module

In Digital Video Broadcasting, the Common Interface is an extensible digital interconnect found in the digital TV market. It is also known as DVB-CI for Digital Video Broadcast Common Interface.

All Common Interface equipment must comply with the EN 50221-1997 standard. This is a defined standard that enables the addition of a conditional access module (CAM) in a DTV Receiver, to adapt it to different kinds of cryptography. Indeed, one of Digital Video Broadcasting's main strengths is the option of implementing the required conditional access capability on the Common Interface.

This allows broadcasters to use modules containing solutions from different suppliers in the same broadcast system, thus increasing their choice and anti-piracy options.

The interconnect is formed between a host and a module. Examples of a host are a digital television or digital set-top box. The EN 50221 specification allows many types of module but only the Conditional Access Module (CAM) has found popularity because of the Pay TV market.

Mode of Operation

A DVB receiver may have one or two slots implementing the Common Interface (CI). The CI uses the conditional access module (PCMCIA) connector and conforms to the Common Scrambling Algorithm (CSA), the normative that specifies that such a receiver must be able to accept DES (Data Encryption Standard) keys in intervals of some milliseconds, and use them to decode private channels according to a specific algorithm.

Those algorithms are proprietary to individual suppliers. Each one uses their own algorithms and there is no defined standard for them.

As the full MPEG-2 transport data stream comes out of the demodulator, and error correction units, the DTV Receiver sends it through the card plugged into the Common Interface, before it is processed by the MPEG demultiplexer in the receiver. If several CI cards are present, the MPEG transport data stream will be passed sequentially through all these cards.

An embedded CAM may not physically exist, as it may be in CPU software. In such a case, only the ISO card reader normally in the CAM is fitted and not the PCMCIA type CI slots.

Even if the Common Interface has been created to resolve cryptography issues, it can have other functions using other types of modules such as Web Browser, iDTV (Interactive Television), and so forth.

In Europe, DVB-CI is obligatory in all iDTV terminals.

Conditional Access Module (CAM)

Main article: Conditional Access Module

The host sends an encrypted MPEG transport stream to the CAM and the CAM sends the decrypted transport stream back to the host. The CAM often contains a smart-card reader.

Standards

The normative DVB-CI standard EN 50221 was defined in 1997 by CENELEC, the European Committee for Electrotechnical Standardization.

According to the Common Interface scheme:

• host : A device where module(s) can be connected; for example, an Integrated receiver/decoder (IRD), a VCR, a PC ...
• module : A small device, not working by itself, designed to run specialised tasks in association with a host; for example, a conditional access sub system, an electronic program guide application module, or to provide resources required by an application but not provided directly by the host.

The specification only defines two aspects, two logical interfaces to be included on the same physical interface. The first interface is the MPEG-2 Transport Stream. The link and physical layers are defined in this specification and the higher layers are defined in the MPEG-2 specifications. The second interface, the command interface, carries commands between the host (receiver) and the module.

The specification does not define the operation or functionality of a conditional access system application on the module. The applications that may be performed by a module communicating across the interface are not limited to conditional access or to those described in this specification. More than one module may be supported concurrently.

The common interface shares many features of the PC Card Standard (PCMCIA). By reducing the widths of the address and data busses it has been possible to include a bi-directional parallel transport stream interface.

Transport Stream Interface (TSI)

The transport stream format is specified by IEC 13818-1 and is the MPEG 2 TS format.

Command Interface

In addition there is a command interface for communication between the host and module.

This communication is in the form of a layered protocol stack which allows the host and module to share resources. For example the module can request the current date and time from the host, or can make the host display messages on the TV screen and can then read keypresses from the host remote control. The resource-sharing feature allows the CAM to request and receive PIN numbers as well as allowing the module to implement an interactive TV service.

The Command Interface is extensible and there are several specification documents available which describe these extensions. For example the host could contain a modem for communication over a telephone line allowing the CAM to implement pay-per-view. However these extensions have often not proved popular with manufacturers.

CI+

CI Plus or Common Interface Plus implements a form of copy protection between a Conditional Access Module (CAM) and the television receiver (display). CI+ is non-compatible update from CIv1. Old television receivers, which have CIv1 CI-slot, can't be used with CI+ CAM.

Definition

CI+ is a specification that extends the Common Interface as found in the digital broadcasting standard. It has been developed by consumer electronic firms Panasonic, Philips, Samsung and Sony, as well as pay-TV technology company SmarDTV and fabless chip maker Neotion^[1].

A first draft of the specification was put up for review early in 2008. The final version was released at the end of May 2008.

By making use of certificates and a certification authority, a trusted channel is formed between the CAM and television receiver, when scrambled content is being received. In the original CI standard, decrypted content could be sent over the PCMCIA interface unscrambled. The establishment of the Trusted Authority has been completed^[2] and an official security certification lab appointed^[3]. With the development of CI+, the standard has now come under the umbrella of the DVB standards organisation ^[4].

A CI+ compliant device must also implement MHEG-5 (or MHP) interactive TV engines to manage navigation of the user within an interactive TV application, using its device remote control.^[5]

Operators

The following operators have currently rolled out CI+ support or plan to do so:

• France
  • Canal+ – launched the 'Canal Ready' label for devices able to receive Canal+ channel
• Germany
  • Kabel Deutschland – NDS conditional access and SMiT CAM modules will be used
• Netherlands
  • Caiway – launched CI+ in October 2009^[6][7]
  • Delta – launched CI+ in 2010
  • Kabel Noord – launched CI+ in 2010
  • UPC Netherlands – launched CI+ in 2011
  • Ziggo – launched CI+ in September 2009, SMiT and Neotion CAM modules are used^[8]
• Sweden
  • Boxer
  • Com Hem
• Switzerland
  • Cablecom (UPC Broadband) – Starting June 2010^[9]
• Italy
  • Mediaset Premium (Digital terrestrial television) - needs CI+ slot on HD television to descramble High Definition channel Premium Calcio HD. No CI+ cams have been sold so far (the only way to receive this channel is to buy an external decoder with HDMI cable).
• Turkey
  • Teledünya
• United Kingdom
  • Top Up TV^[10]

In July 2009 the largest Cable operator in the Netherlands, Ziggo, announced that it will support CI+ based Integrated Digital Television sets (IDTVs) actively.^[11][12][13] In September 2009 the first batch of 15,000 SMiT (Shenzhen State Micro Technology Co., Ltd.) CI+ CAMs was offered by various Dutch retailers, followed in October 2009 by the first batch of Neotion CAMs.^[14] Other supporters include Canal+ ^[15], and conditional access companies Irdeto ^[16] and Conax ^[17]. NDS announced that it will support Kabel Deutschland to deploy CI+ to its customers.^[18]

Compatible TV Sets

• LG 2010 models all LD and LE series also MFT models MXX80D.
• Many of Samsung's new LCD, LCD LED and Plasma model variants with CI+ compatible motherboards.
• Many of Sony's new models including the Bravia W5500 series.
• Philips new 5000 and 9000 series LCD TVs (required firmware pending according to Ziggo).
• Some Panasonic models. It seems that even products with CI+ slots need a new firmware to be fully CI+ compatible. (Update 2010)

See also

• Conditional-Access Module (CAM)
• Free-to-view
• DVB-CPCM
• HDCP

References

1. ^ Cabot Communications Ltd. CI+ Technical Paper
2. ^ Führende TV-Hersteller vertrauen bei der Umsetzung des CI Plus-Standards in Europa auf TC TrustCenter (German)
3. ^ Digital TV Labs to test for CI Plus
4. ^ http://www.broadbandtvnews.com/2011/02/18/ci-plus-back-with-the-dvb/
5. ^ http://www.ci-plus.com/data/ci_plus_specification_v1.2.pdf page 161
6. ^ Caiway CI+ CAM (dutch)
7. ^ Caiway introduces CI Plus modules
8. ^ Digitale Televisie Module (Dutch)
9. ^ Cablecom makes access to digital TV in HD quality and Internet easier and cheaper
10. ^ http://www.topuptv.com/ciplus/
11. ^ Ziggo claims “world first” with CI Plus (visited July 7th 2009)
12. ^ Ziggo Approved SMiT CI+ CAM
13. ^ After initial pioneering, ZIGGO and NEOTION are now further unleashing CI Plus momentum in the Digital Pay TV ecosystem
14. ^ Ziggo starts supply of CI Plus CAMs
15. ^ Canal+ backs CI Plus with ‘Canal Ready’ label
16. ^ Iredeto press release
17. ^ Conax announces CI+ support
18. ^ NDS to deliver CI+ to KDG

19. http://www.oceanbluesoftware.com/images/stories/documents/Articles_Publications/ci%20white%20paper.pdf

External links

• LinuxTV entry for common interface
• EN 50221 Specification
• ETSI TS 101 699 - DVB Extensions to the Common Interface Specification
• R206-001:1998 - Guidelines for Implementation and Use of the Common Interface for DVB Decoder Applications
• Gerard O'Driscoll, The essential Guide to Digital Set-Boxes and Interactive TV, reprinted April 2000
• Jerry whitaker, Television Receivers, 2001
• Consortium DVB
• CENELEC
• CI Plus official web site
• CI Plus Specification V1.2 (2009-04)
• Official CI Plus TrustCenter
• Official CI Plus test lab