Is that really true though? My understanding here is that the biggest blocker is the code signing process - the FBI or the NSA could probably build a backdoored OS, but they couldn't install it on the phone without apple's signing cert. Depending on Apple's internal security, it may very well be impossible for a single person to sign anything other than an official iOS release, making it impossible for an agressor nation or a disgruntled employee or anybody else other than apple as a whole to get a backdoor onto an iOS device.
I believe the parents point is that Apple having a signing key is no different in principle than them making an operating system and signing it. Apple possesses information that can compromise a phone, and if it's possible for an signed OS image to be compromised, then it's possible for the signing key to be compromised.
This is what I've been saying all along. If Apple has the ability to do this then the security is already compromised. The fact that it hasn't been physically created yet is a minor detail.
I also don't understand why they couldn't provide the FBI with an OS that refuses to run on anything other than the specific device in question. Isn't that the whole point of code signing?
