this post was submitted on 02 Dec 2023
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What does that mean practically though?
Depends, I think (don't quote me on this though) blu rays DRM keys can be revoked for that disk, meaning Blu ray players can reject a DRM.
You can also revoke a key hooked to a Blu ray player - making it possible to stop a player from playing any DRM protected DVDs that the key used to work for.
Nah. This would require an update be sent out to every blu ray player, which is not feasible unless they were all standardized to a single database or service for their license keys.
Even if that were the case, which it's not, the device would need to connect to the internet for this scheme to work.
There are several ways to disable your player.
First, the movies themselves are encrypted with a unique key, that key is then encrypted with another set of keys and stored on the disc. Your player will read those encrypted keys off the disc and use it’s own keys to decrypt the key needed to decrypt the movie. If the blu-ray association determines that your player is compromised, they change the way the movie key is encrypted so your players key can no longer decrypt it. This means your player simply won’t play any movies newer than a certain date.
For blu-ray drives in your PC it’s a bit different. Your software player needs a so called ‘host key’ to be able to access the blu-ray drive. Once the key you are using is found to be compromised it’s put on a revocation list. When a new blu-ray movie is mastered they include the latests revocation list on that disc. If that list is newer than the one in the drive, the drive updates it’s internal list using the list from the disc. If your player software uses a key on that list, the drive will refuse to read any movie. You need a new, unblacklisted, host key to be able to play movies again.
There is no need to connect to the internet for any of these schemes, the updates are simply distributed through the blu-ray discs themselves.
So that's what happened to my Blu-ray drive on my PC! I had to flash the firmware to a custom version for ripping to get it to read anything.
That is incredibly shitty behavior. I'm putting the disk that I purchased into my own hardware. The studio already got my money from the sale, why the hell do they care?
They care because:
There would be no problem if you used a licensed software player to simply play back the disc. The problem is you’re trying to rip it with an illicit host key. They don’t want you ripping the disc and spreading it over the internet. You’re only allowed to play it from the original disc using a certified player.
Oh wow okay, so it would fuck over a lot of people but not everyone. I knew about blu ray but I was thinking everyone with DVDs would be safe. If that happens, though, VHS tapes will probably be popular again
For DVD’s it only applies to new movies, old movies will still play but if your player is blacklisted it won’t play any new movies.
The way it works is as follows: The movie data is encrypted using a key, this key is unique to the movie. The key itself is then again encrypted with another key. Since the keys themselves are tiny (especially compared to an entire movie) it’s possible to put hundreds of encrypted copies of the movie key on the disc. Each DVD player manufacturer has their own key(s). When you put in a movie, the player will look at the list of hundreds of encrypted keys, and decrypt the one that can be decrypted with it’s own key.
If a DVD player is considered to be compromised, new DVD’s will no longer include a key that can be decrypted by that player in the list of hundreds of encrypted copies of the movie key on new disc. Alls your old discs still have a key that can be decrypted by your player, so those still work, but new movies will refuse to play.