Decrypting encrypted backup w/discatt.dat - volume key unknown

Discussion of advanced MakeMKV functionality, expert mode, conversion profiles
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pkasting
Posts: 7
Joined: Mon Jun 27, 2022 4:58 am

Decrypting encrypted backup w/discatt.dat - volume key unknown

Post by pkasting »

I have two copies of the Shout Factory release of Candyman (1992) UHD, both of which were scratched when I opened them (other forums have people complaining about that, I'm apparently not the only one).

By piecing together bits from both discs, I've copied all the files to a folder on my hard drive. I also copied discatt.dat there from an aborted encrypted backup. All this was done using the same drive.

Now if I attempt to open that discatt.dat in MakeMKV, it says the volume key is unknown. This doesn't happen when it attempts to read the original discs, so I'm wondering what I've done wrong. Sending in the .tgz to have the volume key added doesn't seem right -- as far as MakeMKV is concerned, this folder should be the same as those discs now, shouldn't it?
Ezatoka
Posts: 406
Joined: Fri Dec 06, 2019 6:55 pm

Re: Decrypting encrypted backup w/discatt.dat - volume key unknown

Post by Ezatoka »

The UHDs very probably have Bus Encryption active as well.

So as long as this is there, just copying the files from the disc won't end in any useful information I'm afraid.

To disable the Bus Encryption, open the UHD in MakeMKV (e.g. until you can select, which tracks you want to extract) and just keep it there. Then start copying the files from the disc via any file manager.

That should result in files being able to be opened with discatt.dat file.
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