My question was why this reasoning was valid. You're repeating the reasoning people have said before, but I don't really understand the reasoning.
In all honesty, I appreciate your effort in trying to explain to me why Apple is creating a master key, but in this case I don't think it helps to create an abstract discussion. I'm well aware of how the encryption in the iPhone technically works.
[doublepost=1456218482][/doublepost]Yes. I follow you.
Whoah, this escalated quickly. First, the FBI doesn't want a special customized software version. They want a phone that is flashed with the special customized software version. That's a whole different story. As far as I know, it's not possible to extract IPSW files from phones. Apple doesn't have to release the special firmware. They can also prevent it from being used by simply not signing the firmware. As I said, it's not even possible to downgrade to an iOS firmware version of choice (of which IPSW files are publicly available). Why would it be possible to flash a custom iOS firmware version that is only available inside Apple and is not being signed by Apple? How would that be possible? Apple has full control.
I can see the slippery slope in this case, but at this point the discussion is not so much anymore about encryption, but more about corrupt police officers. Also, if somehow the whole world got access to this special firmware and if somehow the whole world can actually flash it into a phone, and if somehow the password entry delay built in to the secure enclave (which the 5c doesn't have, but the 5s and up do have) was disabled (that's a lot of "if's"), then still a simple six-charachter alphanumeric password would make all of these efforts useless and make the phone unbreakable.
I think the danger of which Apple / Tim Cook speaks is greatly exaggerated.