KCD & MKB type

[oren.reiss]

Hi All
I am quite a rookie here. So I hope my question is "in the right place"..
Actually I have 2 questions:
1. Suppose my device doesn't have KCD. Can it use both MKB type 3 and 4 or it is obliged to use only MKB of type 3 ?(the AACS spec mentioned:
0003100316 (Type 3). This is a normal Media Key Block suitable for being recorded on a recordable
media.
0004100316 (Type 4). This is a Media Key Block that has been designed to use Key Conversion Data
(KCD). Thus, it is suitable only for pre-recorded media from which the KCD can be derived.
It is not an error for a Type 3 Media Key Block to be used for controlling access to content on pre-recorded
media. In this case, the device shall not use the KCD.)
2. How can I know for sure that BD/HDDVD title is actually using AACS protection (finding out that /AACS directory exists is enough ?)?

[FoxDisc]

Hi All
I am quite a rookie here. So I hope my question is "in the right place"..
Actually I have 2 questions:
1. Suppose my device doesn't have KCD. Can it use both MKB type 3 and 4

Devices don't have the KCD, that's stored on the disc. Devices are provided with device keys that must be used with the KCD or can't be used with the KCD. If they must be used with the KCD, the device will be able to read the KCD from the disc. If it does not use KCD, it won't be able to read the KCD (and won't be able to use device keys from a device that uses the KCD.


[B]2. How can I know for sure that BD/HDDVD title is actually using AACS protection (finding out that /AACS directory exists is enough ?)?

You could just copy the files to a HD and try to play them. Encrypted files won't play.

[lightshadow]

2. How can I know for sure that BD/HDDVD title is actually using AACS protection (finding out that /AACS directory exists is enough ?)?
Isn't the movie encoded with some sort og WMV codec?

This is a guess: I would think that the header of encrypted video file wouldn't contain any plain text like WMV, where the decrypted will regonize as WMV.

If you have Linux try the "file" command on a video file.

[oren.reiss]

Thanks for your responses. I'll describe my problem and then rephrase my questions. I'm trying to write small SW program which analize commercial BD/HDDVD disks/titles. I have PC drive (thus it doesn't supply KCD).
1. Can I use both MKB of type 3 and 4 or I must use only MKB of type 3 ? (in MKB_RO.inf I found MKB of type 4 and in MKB_RW.inf I found MKB of type 3)
2. Since I can't play the title I need to find a way (by SW) to find out if the disk actualy contains AACS decryption (I didn't menage to find in AACS LA specs indication setting that disk contains AACS).

[FoxDisc]

I'm trying to write small SW program which analize commercial BD/HDDVD disks/titles. I have PC drive (thus it doesn't supply KCD).

A Drive isn't supposed to be able to read the KCD and won't deliver KCD to a Host in an authenticated AACS session, but in case you aren't aware, the XBox drive is both a drive and a standalone drive/player combo, so it can read the KCD and with appropriate prodding can be coaxed to give up the KCD.

1. Can I use both MKB of type 3 and 4 or I must use only MKB of type 3 ? (in MKB_RO.inf I found MKB of type 4 and in MKB_RW.inf I found MKB of type 3)

What do you want to "use" the MKB for? An MKB has multiple encrypted copies of the Media Key - one for each defined subset difference set. If it is a Type 3, KCD devices use the same procedure as non-KCD devices to decrypt. If it is Type 4, the KCD devices will decrypt a Media Key Precursor, not a Media Key, and they must use the KCD to do additional decryption to get the Media Key.

(I don't know why a disc would have both T3 and T4 MKBs)

2. Since I can't play the title I need to find a way (by SW) to find out if the disk actualy contains AACS decryption (I didn't menage to find in AACS LA specs indication setting that disk contains AACS).

They assume the disc will have AACS. I suspect that the existence of the /AACS directory is enough to confirm that, but I can't say for sure.

[FoxDisc]

(I don't know why a disc would have both T3 and T4 MKBs)


You might want to look at 7.1.1.1 and 7.1.1.2 of "Advanced Access Content System: Blu-ray Disc Pre-recorded Book."

I haven't spent a lot of time on BD, but they say:

Note that for the BD-ROM that does not contain any encrypted contents, the Type 3 MKB defined in Section 3.2.5.1 of Introduction and Common Cryptographic Elements book of this specification shall be used as the MKB "MKB_RO.inf".
and
For the BD-ROM that contains both encrypted contents and unencrypted contents, the Type 3 or Type 4 MKB shall be used as the MKB "MKB_RO.inf".

[FoxDisc]

Another comment:
I don't think you'd ever find a Type 4 in an MKB_RW.inf The RO is read only and the RW is read write. There is no way to write a KCD to a disc (it has to be pressed in at manufacturing time), so devices that normally use KCD on a pre-recorded RO disc with a Type 4 MKB would not use KCD on a RW disc and the MKB would be labeled Type 3.