this post was submitted on 02 Dec 2023
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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.