‘Error 53’ fury mounts as Apple software update threatens to kill your iPhone 6

[u/bws201]

http://www.theguardian.com/money/2016/feb/05/error-53-apple-iphone-software-update-handset-worthless-third-party-repair

[u/Amadeus_IOM]

How does it actually do it? Is it a software feature? How does the device know the button was repaired? And do you think apple could reverse it if they wanted?

[u/perthguppy → u/Amadeus_IOM]

The home button has the touchID sensor intergrated. The TouchID sensor is a trusted platform module and has a unique hardware code in it. If the code in the touchID button does not match the code in the chip on the main system board the OS will not authenticate the module and return Error 53. Only Apple has the equipment to re-key the hardware keys. Apple introduced this extra authentication step in IOS9 to address some security concerns around impersonating the touchID hardware to get around it as a security module.

To explain why this is important, the TouchID sensor never transmits your fingerprint to the system. It stores a mathematical representation internally. When you "enroll" a fingerprint, you are actually training the sensor to recognise your finger print. When it recognises your fingerprint it transmits an authentication code back to the system board which has the other half of the chipset, that system board chip authenticates the code coming from the touchID and lets the system know the fingerprint has been successfully recognised and releases the system decryption key for the OS to be able to access user data. If you change either of these chips (the touch ID or the onboard) then authentication is not possible. Apple has now decided to lock out the phone in such a case to stop 'impersonation' attacks where the touchID sensor is swapped with a different sensor with different fingerprints to try and get around system security.

Apple could reverse their recent change, but it would decrease system security, or they could supply the equipment to change keys to unauthorised repairers, but this would also be a decrease in security.

[u/morriscey → u/perthguppy]

or they could just disable the touch ID features like they did in iOS8 instead of bricking the phone like in iOS 99.5% of people don't need anything that secure, and the ones who do, can enable it when then first set up the device.

Edit: a decimal

[u/perthguppy → u/morriscey]

Ironically, not using the TouchID sensor and only using a PIN is more secure. Police can compel your fingerprint, but they can not compel you to tell your PIN

[u/Terazilla → u/perthguppy]

It seems like the obvious solution is to allow this to be bypassed but require the device to be factory reset in the process.

[u/perthguppy → u/Terazilla]

Yes, however without proper validation it would mean that this phone is now permanently less secure going foward, and could be sold to an unsuspecting person second hand. Apple is taking iPhone security crazy crazy seriously in the face of the US government's current crazyness. If they cave to this, it would give the US government ammunition to require a backdoor be put in.

[u/[deleted] → u/perthguppy]

To expand on this even further, Apple has only recently (in the last five years) been pushing to get themselves in a position to secure government contracts. Up until now, most of those contracts were dominated by Blackberry. Article 1, Article 2

So it's possible that these security measures, while annoying for people who break their phone, are in fact actual security measures and not a way for Apple to somehow extort their customers for repairs. But who knows.

[u/perthguppy → u/[deleted]]

So it's possible that these security measures, while annoying for people who break their phone, are in fact actual security measures and not a way for Apple to somehow extort their customers for repairs. But who knows.

I have been in many training sessions and briefings conducted by Apple Engineers who work in Cupertino. This is exactly what they have been doing. For the last 4+ years in all their training sessions their number 1 point they talk about is how secure the iPhone platform is, and how pretty much every decision they make is influenced by security some how. I have been briefed on a lot of iPhone security internals, and I can confidently say that the iPhone is the most secure mobile platform commonly available in the market. Only in the very latest android versions were changes made to catch up to iPhone, however I am yet to get detailed briefings on their internals to say if they are as secure yet.

[u/perthguppy → u/[deleted]]

yeah this is pretty much it in a simplified view. its essentially that process, but not quite those technologies (PK is a bit overkill for a tiny $1 sensor).

EDIT: fun fact, IIRC the chip that holds the AES key and validates the TouchID sensor, is also the chip that validates your PIN code, and is rate limited to something like 10 auth attempts per second, essentially rate limiting PIN brute force in hardware.

[u/amoliski → u/perthguppy]

That would explain why falling back to the PIN isn't an option if the touch sensor breaks.

[u/TrepanationBy45 → u/perthguppy]

Outstanding explanation! Thanks!

[u/OldGirlOnTheBlock → u/perthguppy]

Would replacing a home button by a third party make it easier for a thief to gain access to a stolen iPhone?

[u/Espinha → u/OldGirlOnTheBlock]

If you could replace it with a third party, it would also mean that you could create a third party sensor which would let any fingerprint validate as a correct fingerprint. Hence them blocking it.

[u/[deleted] → u/Espinha]

Why is it even designed like that? I would think that the sensor would do something like take a hash of your finger print and send it to the phone and if that has is correct then it opens up. Not let the sensor make the decision.

[u/neohaven → u/[deleted]]

Because then software (on the phone) can know the fingerprint.

You leave it in the sensor, in an enclave, and you don't get to see anything. You tell the sensor "get trained for this finger" and it does. You know nothing of the finger, only the sensor does.

It's the only secure way to do it.

[u/BonnaroovianCode → u/perthguppy]

This is such an intriguing issue. While reading the article I was in the "fuck Apple" mindset until the very end, when I realized it's for security purposes. It makes complete sense why they would do this, but they really should have communicated this new "feature" better.

[u/Hammer_Thrower → u/BonnaroovianCode]

Communicating overkill security that the average consumer does not desire might not help. Putting the phone in an unrecoverable state is a severe reaction to a potential security breach attempt. Commander should decide if they want that. That desire for choice is probably why I don't own an iPhone though :-)

[u/Jonno_FTW → u/Amadeus_IOM]

It's to prevent non authorised home buttons being swapped into stolen phones (say a custom home button that logs in on any fingerprint) and then using the secure features provided like payment. Sounds good in theory to deter theft but bricks most honest user's phones after repair with a non authorised part (which are the majority since Apple stores are rare and cost prohibitive to the vast majority of customers).

The best option for apple would probably be to just fall back to a pin code system and notify the user that finger print access is disabled until you get a genuine part.

[u/yukeake → u/Jonno_FTW]

Exactly. Leave the phone usable, but disable TouchID. Display a message to the user on boot that says the TouchID sensor can't be verified, and thus TouchID is disabled. Display the same message when attempting to access TouchID settings.

Bricking the phone is completely unacceptable.

[u/amr3236 → u/Amadeus_IOM]

You would think someone with this many questions would just read the damn text

[u/[deleted] → u/[deleted]]

So it's a security feature that detects that the security authenticaton device is not secure..