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What the heck is this for and what does it mean?
It's the illegal prime number used to decrypt DVDs.
Can you eli5?
https://duckduckgo.com/?q=09f9
oh child come on I am WAY too dumb to understand that Wikipedia article. can you just explain it?
It's the key needed to unencrypt a video DVD, it's how people were able to make duplicates of DVDs. This was technically illegal to use thanks to the DMCA, but not illegal to know, so people had fun with it and plastered it on T-shirts, mugs, etc...
I remember thinking I was hot shit for ripping a ton of Netflix and Redbox movies back in the day...
Blockbusters mail rental service was amazing since if you returned the movies to the store instead of mailing them they counted as a free in store rental coupon AND would flag the movie as returned and prep the next set to be sent to you. They were slower than Netflix but if you were willing to go into Blockbuster, it was crazy worth it.
I had Netflix and Blockbuster and a huge rotation of DVDs coming and going.
I didn't have time to actually watch anything I was ripping, lol, but it was fantastic to expand the collection.
I had a high school acquaintance who rented a ton of games from Blockbuster right as they went under. I was so mad I didn't think of that...
Tldr: DVDs can not easily be played unless using authorized hardware (or software in the case of WinDVD)
Once the key was leaked, this was no longer the case, and now DVDs can be played by anyone with the key (enabling piracy)
It’s the password to unlock the content on the DVD (well, HD DVD / Blu-Ray) so you can just copy the video from it for redistribution.
How do you get to the password prompt?
More technically, the data on the disk is encrypted with that “password”, so there’s not really a password prompt. It’s more like your DVD player will have this encryption key stored on it somewhere (possibly on a separate chip where it’s hard for somebody to extract it and distribute it on the internet lol), and then it will automatically run the decryption algorithm with this key on the disk contents transparently.
Blue ray movies are encrypted to prevent unauthorized copying. Someone figured out and published the decryption key making copying possible. The movie companies went nuts and tried to suppress dissemination of the key, but it was out of the bag. That 09f9 number is the key that was formerly a big secret. Now that you know it, you can copy blue ray discs.
Why didn't they just change it? Set a new encryption key for every disc?
Any Blu-ray player has to know the key in order to play a disc. So they’d have to have some way to update every single player. There would be no feasible way to do that.
Can you imagine having to update your Blu-ray player each time a new movie came out?
Man, you got me with the verified profile picture! Good job!