Common Interface
In Digital Video Broadcasting (DVB), the Common Interface (also called DVB-CI) is a technology which allows decryption of pay TV channels.
This is a defined standard that enables the addition of a CAM in a DTV receiver to adapt it to different kinds of cryptography.
The EN 50221 specification allows many types of modules but only the CAM has found popularity because of the pay TV market.
Indeed, one of Digital Video Broadcasting's main strengths is the option of implementing the required conditional access capability on the Common Interface.
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.
In such a case, only the smart 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.
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.
By reducing the widths of the address and data buses it has been possible to include a bi-directional parallel transport stream interface.
This communication is in the form of a layered protocol stack which allows the host and module to share resources.
First two of these three are necessary for initial handshaking between CAM and its host, while the CA Support resource is necessary for descrambling the selected channels.
The main addition introduced by CI+ is a form of copy protection between a CI+ conditional-access module (referenced by the spec as CICAM, while CI+ CAM seems to be a more precise abbreviation) and the television receiver (host).
Old television receivers which have a CIv1 CI-slot can be used with CI+ CAM and vice versa, but for viewing only those of TV programs which are not marked as CI+ protected.
CI+ specification 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.
[5] The main evolution of this version is to add USB as physical layer to replace the aging PC Card interface.
This is done by broadcasting a Service Operator Certificate Revocation List (SOCRL) in a DSM-CC data carousel.
[7][failed verification] The following operators have currently rolled out CI+ support or plan to do so: In July 2009 the largest cable operator in the Netherlands, Ziggo, announced that it would support CI+ based Integrated Digital Television sets (IDTVs) actively.
