Interfaces and Encryption
The ISDB specification describes a lot of network interfaces, but most importantly the Common Interface for Conditional Access ARIB STDB with the Common Scrambling Algorithm CAS system called MULTI required for descrambling television.The ISDB CAS system is operated by a company named BCAS in Japan the CAS card is called BCAS card. The Japanese ISDB signal is always encrypted by the BCAS system even if it is a free television program. That is why it is commonly called Pay per view system without charge.citation needed An interface for mobile reception is under consideration.ISDB supports RMP Rights management and protection. Since all digitial television DTV systems carry digital data content, a DVD or highdefinition HD recorder could easily copy content losslessly. Hollywood requested copy protection this was the main reason for RMP being mandated. The content has three modes "copy once", "copy free" and "copy never". In the past, time shifting was done with a video cassette recorder VCR and its timer function, in which the VCR tunes into the appropriate station and records the show onto video tape.
In "copy once" mode, a program can be stored on a hard disc recorder, but cannot be further copied only moved to another copyprotected media—and this move operation will mark the content "copy one generation", which is mandated to permanently prevent further copying. "Copy never" programming may only be timeshifted and cannot be permanently stored. Currently, the Japanese government is evaluating using the Digital Transmission Content Protection DTCP Encryption plus NonAssertion mechanism, to allow making multiple copies of digital content between compliant devices.MULTI is a symmetric key algorithm with variable number of rounds. It has a block size of bits, and a key size of bits. A bit implementationdependent substitution box constant is used during key schedule. Scramble and descramble is done by repeating four basic functions involutions.Time shifting is the recording of programming to a storage medium to be viewed or listened to at a time more convenient to the consumer. Typically, this refers to TV programming but can also refer to radio shows via podcasts.In recent years, the advent of the digital video recorder DVR has made time shifting easier, by using a electronic program guide and recording shows onto a hard disk. Some DVRs have other possible time shifting methods, such as being able to start watching the recorded show from the beginning even if the recording is not yet complete.
Problems
Every TV broadcast including free TV is encrypted with CopyOnce, which allows users to record to a digital media DVHS, DVD, HDD, etc but does not allow dubbing to another digital media. On the other hand, the CopyOnce technology does not prohibit all types of dubbing. It is possible to dub to an analog media such as standard VHS and if recorded to an HDD, it will allow users to Move the contents to a DVHS, but not copy. In contrast, seg digital broadcasts which are for lowbandwidth mobile reception and occupy th of a digital channel, are transmitted in the clear and do not carry copy protection information.Many users are also very worried about the recent news of severe protection in the future. There are modes in ISDB to not allow the output of signal from an Analog connector Dconnector, Component, Composite, SVideo, etc. There are already plans to not allow analog output for Copyright Protection reasons. Same as Bluray and HD DVD This will make all currently sold STB Tuners, and the majority of LCDPlasma TVs without HDMI inputs unusable.
Plus all analog VHS, DVHS that can only record via analog input, and all DVD players will also become unusable. These more limiting copy protection technologies will all start after analog broadcasting ends when there wont be any choice for viewers. Currently, no financial assistance schemes have been announced, and viewers without proper devices will be forced to buy a new compatible TV or set top box in order to view ISDB broadcasts. Though not clear, it is said that there are also plans to protect all programs with CopyNever.The copy protection on ISDB broadcasts can be circumvented with the proper hardware and software.The BCAS card is required to decode all broadcasts. These cards are included with every digital TV or Tuner at no charge. To use this card, you must agree to the statement written on the registration card. Despite the fact that the card must be inserted to watch TV, if you dont agree to the statement, then the user cannot watch digital broadcasts. Essentially, users are forced to agree with the statement. Though registration is not required, it is recommended to fully enjoy interactive programs. Unregistered BCAS card displays a watermark in a corner of the screen, suggesting the user to register. However, many viewers worry about the leaking of personal information, and the powerrights the TV stations have to access personal information for almost every citizen in Japan. In case of loss or destruction, new BCAS card of the same number can be issued for a fee of , yen.
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