Not entirely correct.
(note, I own a 1st generation Fusee-gelee vulnerable switch, which has never touched nintendo's servers, and have extracted my own keys from it. The emulator I use likewise, is configured to disable the networking stack, so the emulated switch never talks to nintendo's servers)
What the keys REALLY do, is uniquely identify that switch, and that cartridge. The actual decryption keys still use a master signing key, and all switches are able to decode all cartridges/downloads, without pulling another cryptographic key from Nintendo.
Nintendo even made it so people without internet access, can get switch console updates, via the cartridges themselves-- If the cartridge has a minimum system version requirement, it comes with that system version's installer data packed inside it-- and updates the console to that minimum required version, before allowing the cartridge to play.
This said-- THERE ARE pirate copies of the title and prod keys out there, that are clones of a banned switch's keystore. These keys cannot talk on nintendo's servers; Nintendo has blacklisted the keys (which identify a unique console, for the purposes of software license validation, and very little else), so you cant, for instance, play Mario Kart with your friends (unless you use the LAN exploit, and a VPN tunnel).
For wholly single player games, like BotW and TotK, this is a great big nothingburger.
Nintendo's consoles *DO* phone home to the mothership about what games you have been playing (including the unique metadata collected from the console's unique key, and the game cartridge's unique key) and if Nintendo finds this phoned home data suspicious in any way, they will just ban your console, ban your Nintendo account, and tell you to pound sand. So-- ProTip-- Dont trade cartridges with lots of friends, Nintendo will consider it piracy, and ban the shit out of you and your friends.
What is the benefit of extracting and using my own keys, if I never play online anyway?
I am actually using the emulator legally. That's what. My hacked switch lets me dump my own copy of the game as well, with my own uniquely keyed dump.
No laws are really violated, other than perhaps, anticircumvention DMCA bullshit with the dump itself. Chuds like Nintendo and pals have been trying to claim that format shifting and software backups are illegal for decades now, and have been pressing the international trade unions of the world to try and engineer legislation to that effect.
Nintendo can go choke on a toxic amanita.
The only thing the unique keys do for Nintendo here, is uniquely identify consoles and game cartridges. It is not involved in the decryption in that capacity--
All switches can decrypt all Switch cartridges.
Full stop.
If you have a valid keyset-- even one that has been banned-- you can decrypt the data.
Fun fact-- Yuzu and pals can play games that have been UNENCRYPTED (as there *ARE* tools to do this!!), since this is how you play modded versions of switch games.
From an anticircumvention standpoint, the only obstacle they had in the way was the AES256 signing key stored in the bootloader checksum secure enclave of the Tegra SoC, to protect the boot process.
the Fusee-Gelee exploit rendered that moot, but skipping that process entirely, giving unfettered access to the switch before the nintendo OS can even load.
This is how you get your title keys. You use this exploit to load custom software that extracts the keys from the console's processor, which then gets saved to your microSD card.
As others have pointed out, Yuzu does *NOT* give you a set of these keys. They DO tell you how to get your unique keys out of your hacked switch-- but again, even the pirated keys (From a banned switch) will work just fine, as long as you dont try to play online, or use the e-store.
As others have rightly pointed out-- giving a means to legitimately use ones own keys to just play games in a blessed emulator anywhere, would have made Yuzu unnecessary, and been more useful generally. E-shop downloads would be transferrable, and people could play on SteamDecks legitimately. Nintendo would actually SAVE money (By not losing money on sales) this way.
However, Nintendo has a hard-on for being the warden of a panopticon, and wont allow that.
Again, *ALL* the uniqueness of the keys currently does, is allow Nintendo to notice when you lend your console to a friend, or your friend lends you a cartridge -- It's the vanguard soft-option vanguard on killing the second hand market, and the right of first sale.