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Comment by paxys | Hacker News Reader

Everyone commenting with "security" is missing the point (and hasn't watched the first minute of the video). In previous versions of the iPhone the screen was not part of the FaceID system and could be independently replaced. The sensor/cable/motherboard were all still cryptographically paired and secure. This is a brand new limitation in iPhone 13.

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"Security" is an easy cop-out to justify lock-in. That people that call themselves technically minded still fall for it is a miracle.

What security scenario would you even use as a basis here? Ridiculous...

Totally not resales negatively affecting Apples turnover.

Those OEM parts can either come from broken devices... or they can come from stolen ones. Not that I agree with Apple's restrictions, but from a theft victim's point of view, would they like having the thief make good money from the phone?

Wow, sounds like we should cryptographically sign all replacement parts for anything, they could come from a stolen product after all!

That aftermarket car bumper? Sorry, can't use it, might come from a stolen vehicle.

Car makers actually have the same thing. Not on bumpers, but on ignition keys and ECU (and possibly more). You can't swap out the ECU without getting keys reprogrammed by the dealer.

> without getting keys reprogrammed by the dealer.

Or some guy that figured it out with or without insider knowledge (which also usually means anyone can make a key for your car).

To make a key for your car they'd need to break into your car first, so...

Twin that with repeater attacks from people that leave their keys close to their door (like many people do) to unlock by proximity and that’s how a lot of newer cars are stolen.

I was both insanely impressed and woefully dismayed that the key guy had to hack my car to sell me a key.

This isn't entirely true. For example, I can purchase software to program keys in Fords.

Specialized smaller shops also have the ability.

Currently there is NO WAY for me to change a screen on apple device without an annoying message or faceId issues on the 13. I cannot purchase a programming software.

I can get my key reprogrammed at Walmart. What do you mean?

You can chose not buying an iPhone.

My phone got stolen once and I still like the option to repair my device. Weak hypothetical.

This does nothing to target businesses that make money via theft. If I steal iPhones and sell them how they come I still make money, if I repair iPhones with stolen parts I also still make money and have the exact same extreme limitations as my legitimate counterparts.

If the parts are useless to be used, who would buy those stolen iphones?

If I'm selling unmodified stolen iPhones then they wouldn't be useless.

But how would your customers activate said stolen iPhones?

This can be achieved by signing the parts and once a phone is reported as stolen, the respective parts get disabled.

Trivial solution for someone like apple.

Since when is it anyone's business (within the limits of the law) where I get my parts from?

I'm sympathetic to the guy, but I still don't really see this as a big deal. There's not a ton of space in a modern smartphone, so it seems entirely plausible that some legitimate design change or manufacturing difficulty caused the signed components to get moved to the screen. (He says it's not purely a new limitation, which would be more questionable - the cable which was previously cryptographically paired now is not.)

Maybe but why can't the end user simply be tasked with accepting the new screen signature? That's how GPG, Secure boot, etc. all work. You just have a persistent list of trusted signatures.

Because not allowing customers the opportunity for competence or independence increases the amount of money Apple can extract. The walls in the garden only ever get higher.

Because now you can defeat the security on a stolen phone by replacing the screen and clicking "yes".

Every biometric system on phones also forces the user to set a password/pin as fallback. So no, you cannot just gain entry into a stolen phone like that.

Any phone that lets you just circumvent security by removing a part wasn't secure in the first place.

Majority of users are not in the position to understand what a signature is and whether they should accept it or not.

So everyone will just click "Approve" in order to get their phone back. In which case what is the point of even having trusted signatures at all ?

"We detect that your phone screen has just been changed. Is this expected ?" with a "yes", "no" buttons for answers.

Pretty sure this is understandable.

So what happens if you click “no”?

"It is possible someone tampered with your phone to gain unauthorized entry","Please contact apple-authorized support".

How do you deal with a rouge parts supplier, phone store, phone store employee, etc?

I know this joke! Stop telling them embarrassing stories? I’m sure you meant rogue though.

Yes, in theory it might be a problem. In practice any supply chain that resulted in a significant issue like this would be easily prosecuted so let wetware systems handle the things they’re better suited to.

If your role is to protect data you could always require an OS reinstall before the new part becomes functional, removing any incentive from replacing parts to gain access to a user's existing data.

But the entire assumption that parts are restricted for security reasons is flawed. "Security" is done in the main SoC, the peripherals such as Face ID/Touch ID sensors should just be dumb input devices providing the face/fingerprint data to the SoC which authenticates them. There is absolutely no reason why those should be part of the chain of trust.

If Apple had the user's best interests in mind they could implement a system where if the device detects any component has been tampered with, the user will be alerted during the first boot up and it will require the user to manually activate the new touch id sensor. That way if you get that message without knowledge of your display being replaced you could be wary of someone trying to break into your phone without sacrificing repairability.

Funnily enough if your front camera stops working your whole phone stops working with the current setup.

I went to an iPhone repair shop because my phone was boot-cycling and the repair guy basically said “yep, that’s a faulty front facing camera, stops it booting”. Then he unplugged it and the phone was able to turn on. At this stage he could even plug the camera back in and it worked… so I’m assuming it was actually an issue with the faceID signing process at boot that bricked my iPhone. The repair guy said it was really common.

He could replace everything except Face ID on the device which was a big shame as it killed the resale value (he could replace the earpiece/camera module with one that didn’t have faceID which is presumably to avoid issues with signing).

Seems like a tiny chip that delayed power (or held the camera’s RESET line high) for a few seconds after boot would solve this.

Maybe someone will make a flex cable that has it all integrated.

Sorry, I mean it all worked except for FaceID which remained non-working.

So the phone boot cycles if the cable is in, but if you take it out and then insert it back during boot the front camera and front speaker work but not FaceID.

Permanently disabling FaceID is a feature, not a bug. FaceID (and the inability to really turn it off) are the reason that I will leave Apple behind when I finally have to replace my current pre-FaceID iPhone.

What do you mean the inability to really turn it off?

I don't even have my face registered and just use a passcode for everything.

If someone's able to do some kind of physical attack that involves a cable swap style mitm to mess with the face id system, what stops them from also rebooting your phone once?

You can do it so that only after successful unlock it stops showing the message. This is trivial.

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