D-Theater Encryption
Dear Gary: I have a question about copy protection. When you play a D-Theater tape on a JVC HM-DH30000U, you get a decrypted FireWire stream out, which can be played by non-D-Theater devices, like a Japanese 35000. If you try to hit record on the 35000, you get an error 202 (or 203), which indicates the presence of the 5C copy-never flag. If you play a regular DVHS 5C copy protected tape on a 35000 and try to copy it, you get exactly the same thing. In other words, there is not a shred of difference between a D-Theater tape and a standard D-VHS recording in terms of copy protection: it’s always the 5C copy-never flag. Am I missing something here? Where is the added security that D-Theater is touted to provide?
robena, Advanced Member, AVS Forum
Editor-In-Chief Gary Reber Comments:
Firstly, 5C or DTCP is an authentication/ encryption system carried (currently) over IEEE1394. Flags placed on broadcast content can carry Copy Never, Copy Once, and Freely Copy data and signals carried on IEEE 1394 will first carry out authentication to see if the receiving device is up to DTCP specs and then send the signals with the required copy restrictions. D-Theater is a proprietary encryption system which is administered on pre-recorded (HD) content. Basically, due to the nature of the content, it is a Copy Never encryption system. The encryption is on the tape and decryption works together with the D-Theater licensed VCR. Also, the system can be passed through DTCP as well as HDMI interfaces. Carried on either of the above interfaces, if illegal copying is to be done the DTCP or HDMI encryption must be broken first to get to the D-Theater encryption (which is also perceived to be more robust than either of the above encryption systems). Therefore, the encryption systems between DTCP and D-Theater are totally different and used for (at times) different purposes. Of course, you understand that JVC will not comment on its security system because none other than duplicators need to know how the system works and the fewer that know the more secure the system
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