Deep Dive: Bambu's Authorization Control Scheme
https://bambuzled.github.io/posts/bambu-auth-control/
The recent fiasco with Bambu's legal threats against the OrcaSlicer-bambulab fork motivated me to go figure out exactly how Bambu's newer "Authorization Control" scheme works. Spoiler: it's carefully designed to lock out 3rd-party code, not improve security.
My analysis is based on what you can see in decrypted network traffic, plus the old Bambu Connect code leak. So it may not be 100% accurate, but it's definitely more accurate than some of the popular documentation repos on GitHub at the moment (many of which seem to be entirely AI generated without sufficient human validation).
The TL;DR is that Bambu applications 'bootstrap' signing keys to printers by sending certificate chains to them. Each app requests a fresh copy of its assigned cert+key from the cloud at startup. This key probably just lives in memory, so the applications include a bunch of anti-debug features to make it really hard to access that key. But if you got one of the keys, you should be able to sign your own printer messages via 3rd-party code over the local network while still having access to all of Bambu's cloud features.
I suspect most people in this subreddit aren't too concerned about losing cloud access and just use Dev Mode, but a lot of average users are missing out on great 3rd-party software (like OrcaSlicer) because it can't be used together with the convenience of cloud-connected printers.