Partially matching entries in KEYDB.cfg

[maetel99]

I've been doing some testing on discs I own and comparing what I find with the latest KEYDB.cfg.

I've found several discs in which the following fields appear to match between KEYDB.cfg and my discs:

Disc title
Date
Media Key
CPS Unit Keys

However these fields are different:

DiscID
Volume ID
Volume Unique Key

That would appear to indicate that the Unit_Key_RO.inf files on the discs are different while the encrypted media files are the same.

Is this situation common?

[nalor]

Can you give an example? I'd guess that the entries are not "validated" and therefore it's possible that they are simple wrong.

[richy]

Is this situation common?

Yeah, pretty common. I've had multiple copies of the same disc that exhibit exactly what you've noticed. Off the top of my head... Romancing the Stone was one. Two copies I had were exactly the same, the third one had different DiscID etc but same Media Key, Unit key(s?) etc.

My rough understanding of why this is is something to do with multiple runs of the same disc being manufactured in tandem or at least multiple batches being pressed at different times and each machine pressing the discs allocates that specific batch a unique Disc ID, Volume ID etc whilst keeping the rest of the keys the same. For releases where there's a high print run it'll be more common, with other titles which maybe only get pressed in low quantities then it'll be less likely as there's probably only ever one print run done.

[Toad King]

Just from the current KeyDB, there are over 50 entries for The Dark Knight and the majority of them use one of two Media Keys/Unit Keys. This is very common for discs with long prints.

[maetel99]

One of the discs I tried was HOBBIT_PART1 (The Hobbit), which has quite a large number of entries in the KEYDB. None of them fully match my disc, however.

The thing is, you really only need the unit keys to decrypt the disc. You can even test to see if a given unit key actually is decrypting correctly.

Seems like maybe there should be a better way of indexing the discs in the KEYDB to avoid all the slight variations being listed separately with the same unit keys...

[richy]

Seems like maybe there should be a better way of indexing the discs in the KEYDB to avoid all the slight variations being listed separately with the same unit keys...

I don't mean this as rude in any way (seriously!) but I think you're trying to fix a problem that doesn't really exist.

The KEYDB.cfg is pretty small, relatively speaking, and I can't see any method to "improve" or streamline it that isn't just more complicated ultimately.

It works fine, is supported by multiple different applications, has ALL the keys in it (even ones that you might not "need" to just play discs but are useful to know, all the same) and is pretty simple to understand and update etc.

If it was several gigabytes in size then maybe this would be something to look further into but the fact that there might be 50+ entries with the same unit keys for a particular title is fine (as far as I'm concerned at least). It just reflects that there are 50 discs that share the same unit key(s) but have different DiscIDs etc.

TL;DR - Why reinvent the wheel? :)