LibreDrive outside MakeMKV

[iskander]

Hello,

Despite reading a ton of topics here about LibreDrive, I still haven't quite grasped the details essential for me.

From what I’ve understood so far, it’s a mode of operation for an optical disc drive that, as of now, only one program—MakeMKV—can make use of. Is that correct?

Here’s the practical issue I’m facing: I’d like to play an AACS v81 Blu-ray disc on my Linux machine. By "play," I mean the following process: https://web.archive.org/web/20250923123 ... wsmy.name/.

I’ve already successfully ripped the disc using MakeMKV. I’ve never flashed my drive, so the firmware is stock. Now, MakeMKV reports that the highest AACS version supported by the drive is 81. The disc title doesn’t seem to be present in the publicly available KEYDB file.

This raises two further questions:

1. If I flash the drive to MK firmware now, will it be able to decrypt the disc (i.e., allow my machine to play it)?
2. If not, would flashing to MK firmware before the drive saw the disc have made decryption possible? Does the answer depend on the drive’s highest AACS version? Unfortunately, I didn’t check the highest AACS version before inserting the disc.

[dcoke22]

A drive's highest AACS version is a record of the highest version of AACS that the drive has ever seen. It will change regardless of wether or not the drive's firmware has been flashed to support LibreDrive.

https://forum.makemkv.com/forum/viewtopic.php?p=184611#p184611

[MrPenguin]

I’ve already successfully ripped the disc using MakeMKV. I’ve never flashed my drive, so the firmware is stock. Now, MakeMKV reports that the highest AACS version supported by the drive is 81. The disc title doesn’t seem to be present in the publicly available KEYDB file.

Have you tried adding that disk's key to the KEYDB file, since it is currently missing? Since the highest MKB version that your drive has seen is MKBv81, you should be able to find an unrevoked host certificate to allow libaacs to obtain the disk's VID. Has the aacs_info tool already computed the disk's Media Key for you?

[iskander]

MrPenguin,

I would be happy to add the disk's key to the KEYDB file (I suppose it's the VUK we are talking about), but the latest certificates/keys available in the public KEYDB file are apparently revoked by my drive. To this day, I've never heard of aacs_info tool. I found out about the revocation with bd_info tool. I will later try aacs_info, since it's apparently part of libaacs.

[mike admin]

Overly simplified, LibreDrive does two things:
1. Allows one to read VID from disc
2. Disables bus encryption

You can solve (1) with keydb. But you still need LibreDrive microcode(or a valid UHD host certificate) for (2).

[keydb_helper]

Overly simplified, LibreDrive does two things:
1. Allows one to read VID from disc
2. Disables bus encryption

You can solve (1) with keydb. But you still need LibreDrive microcode(or a valid UHD host certificate) for (2).

Aside from microcode and valid host certs, it is also an option to use patched firmware with LG/Asus drives which disables bus encryption entirely.

But my preferred option is to use a microcode extension to calculate the unique drive seed value and then use the drive seed to calculate the RDK from the VID when required. This allows for playback/decryption of any disc as long as the keydb has at least the VID and UK.

[MrPenguin]

But my preferred option is to use a microcode extension to calculate the unique drive seed value and then use the drive seed to calculate the RDK from the VID when required. This allows for playback/decryption of any disc as long as the keydb has at least the VID and UK.

Interesting! My understanding is that each drive has its own unique "drive seed" (16 bytes), and that each RDK is actually just the disk's VID encrypted using this drive seed. Hence why each RDK depends on both disk and drive.

OTOH it has taken Mike 2 years to add LD support for the most recent batch of Pioneer drives. The probability therefore of "teaching" every UHD drive to provide its drive seed as you suggest would seem to be "very low" - unless Mike were also to help .