If the manufacturer's ability to sign code is a backdoor, then so is absence of code signing.
You're assigning them the moral failure to perfectly secure the iPhone only because they have tried to secure it at all. It's subject to strictly fewer attackers; in my book, that's a good thing.
In that universe, you can run any encryption software of you're choosing, and verify the software written by others.
Nobody has more privileges over the device that exceed those of the device's owners.
> You're assigning them the moral failure to perfectly secure the iPhone only because they have tried to secure it at all.
Legally and ethically, it doesn't matter.
Legally, cryptography is protected expression, and you can use cryptography to encrypt whatever you like -- including information that would otherwise be subject to a lawful search under the fourth amendment.
However, the fourth amendment doesn't have a crypto "participation award" clause; if you left a backdoor in place, the government can compel you to use it.
Ethically, if they chose to leave themselves this backdoor (and all the others), the system is weak. If it's not the FBI today, it's the NSA with a NSL tomorrow, or foreign espionage, or a disgruntled employee, or new corporate management.
With physical access I can replace any security software you have in place. The hardware needs to enforce its integrity.
I work in tech and I wouldn't feel comfortable making all those decisions.
[1] - http://www.nytimes.com/2015/09/08/us/politics/apple-and-othe...
They can install new software, inject code into auto-updated applications, MITM SSL by hooking local device APIs, MITM iMessage by using their CA to sign new certificates. Their control over end-user devices is astonishingly complete.
They can do all of this without no external validation (except when jailbreaks are found), as the platform itself prevents 3rd parties from decrypting Apple's OS updates, viewing the operation of the device, introspecting Apple's code, or introspecting the encrypted application code shipped on the device.
They've intentionally done this, and justified this massive set of backdoors under the ridiculous assumption that they can defend device owners against all possible compromises of Apple's trust position, both from within (such as changing business management) and without (governments, espionage, and compromise), not just now, but many decades to come, all without any checks or balances.
How is this not the very definition of backdoor?