Apple Facing Class Action Lawsuit Over 'Error 53' iPhone 6 Bricking

So... They made third-party repairs, which annulled their warranty, and bricked their phone and now they're suing? Why does Apple owe them anything, exactly? Didn't they agree to Apple's terms when they purchased the device?

There is so much misinformation about this, I'm going to repost the technical explanation I gave in the other thread:

The API hides a lot of the implementation details, so most developers won't know how it really works, but Apple document it in their iOS Security Guide (PDF) ('https://www.apple.com/business/docs/iOS_Security_Guide.pdf').

When you boot your iPhone up, the filesystem is encrypted. It's just full of meaningless junk; you can't use the phone. Once you enter your passcode for the first time, the system reads the filesystem key (which itself is stored encrypted by your passcode), and tries to decrypt it. If your passcode is correct, it will end up with the correct filesystem key, and it can unlock your iPhone's hard drive and read useful data from it. This filesystem key is called "NSFileProtectionComplete".

(NSFileProtectionComplete): The class key is protected with a key derived from the user passcode and the device UID.

... when a passcode is entered, the NSFileProtectionComplete key is loaded from the system keybag and unwrapped.

IMPORTANT: At this point your phone is unlocked. That is all there is to it. This filesystem key gets placed in the Secure Enclave so your iPhone can read/write from its hard drive. We haven't used TouchID or fingerprints so far, just a passcode. This is why you always need to give your passcode after a restart.

So how does TouchID work, exactly?

Let's look at what happens when you lock the phone, and how it's different between TouchID and non-TouchID:

If Touch ID is turned off, when a device locks, the keys for Data Protection class Complete, which are held in the Secure Enclave, are discarded. The files and keychain items in that class are inaccessible until the user unlocks the device by entering his or her passcode.

With Touch ID turned on, the keys are not discarded when the device locks; instead, they’re wrapped with a key that is given to the Touch ID subsystem inside the Secure Enclave. When a user attempts to unlock the device, if Touch ID recognizes the user’s fingerprint, it provides the key for unwrapping the Data Protection keys, and the device is unlocked.

So basically if you have TouchID disabled (passcode only), this key gets thrown away and you need to enter the passcode again next time you unlock. It's the exact same process as you go through on first-boot.

What Apple is saying here is that TouchID just holds on to the key which you already obtained via your passcode for a while (48 hours if the device stays on). But is TouchID really completely optional? Let's ask Apple:

When Touch ID scans and recognizes an enrolled fingerprint, the device unlocks without asking for the device passcode. The passcode can always be used instead of Touch ID

Okay, I guess that settles it.

What about other stuff like iTunes/ApplePay purchases? How does that work with TouchID?

Touch ID can also be configured to approve purchases from the iTunes Store, the
App Store, and the iBooks Store, so users don’t have to enter an Apple ID password. When they choose to authorize a purchase, authentication tokens are exchanged between the device and the store. The token and cryptographic nonce are held in the Secure Enclave. The nonce is signed with a Secure Enclave key shared by all devices and the iTunes Store.

So when you enter your iTunes Store password the first time after a reboot, your device gets a temporary token to use for purchases, stores it in the Secure Enclave, and guards it behind TouchID. Again, it's totally optional; just a shortcut for entering your password.

The same applies to Apple Pay:

The Secure Element will only allow a payment to be made after it receives authorization from the Secure Enclave, confirming the user has authenticated with Touch ID or the device passcode. Touch ID is the default method if available but the passcode can be used at any time instead of Touch ID. A passcode is automatically offered after three unsuccessful attempts to match a fingerprint and after five unsuccessful attempts, the passcode is required. A passcode is also required when Touch ID is not configured or not enabled for Apple Pay.

Man, Apple is really going to regret writing this document...

So yeah, in conclusion:

1. it is totally technically possible to rip the TouchID sensor out of your phone and still be able to unlock it (assuming you have the passcode).
2. TouchID does not seem to be essential for any single feature of the device; it is only ever a shortcut for entering the passwords you have already recently entered in to the phone.
3. It's really weird that Apple only check the TouchID sensor's integrity when they update the OS. Surely they should check that on every boot?

So what did Apple do wrong?

1. Apple should have communicated better (not when performing the update, but when buying the device!) that the TouchID sensor can only be replaced by an authorised technician.
2. If the TouchID sensor is compromised, they should fall-back to the passcode. As I said, the passcode is the only thing you really need to unlock the device.

Law firms? I just did all of your investigation work for you. Feel free to cut me a cheque.

EDIT: Rewritten for greater clarity for non-technical folks.
EDIT2: My personal feeling is that this is a bug -- I mean, what if the legit sensor developed a hardware fault? You don't want the machine to just lock all access. I think Apple did intend to fall-back to the passcode if the TouchID sensor, but unfortunately this is a catastrophic bug: even if Apple fix it, once you're locked out of the phone you can't update to get the fix. They should release a software update ASAP and repair any affected phones for free.

Totally justified lawsuit. There is absolutely no reason to brick the phone for an optional feature such as touchid. Invalidate the fingerprints and allow the user to continue using the phone via the regular pin.

Seems like they have legit case.

So... They made third-party repairs, which annulled their warranty, and bricked their phone and now they're suing? Why does Apple owe them anything, exactly? Didn't they agree to Apple's terms when they purchased the device?

There is a lot of misinformation on this subject. The "brick" happens when someone replaces the TouchID sensor--with a GENUINE OR 3rd party part. Apple is most likely within their right to disable TouchID when they detect a mismatched sensor as it's a security risk. However bricking the device and not giving any warning is probably going too far.

It amazes me how little people actually care about their security (and do not confuse security with privacy here). Apple is trying to protect its users, but they are too stupid to realize.

But on the other hand, Availability is a part of the CIA triad so bricking the phone does violate this premise.

However, Apple is doing this because a piece of hardware inserted between the Touch-ID Sensor and the Secure Enclave could in theory either intercept scans or access the enclave.

They are doing this to protect you, not as a "screw you for trying to fix your own phone." People will always see what they want to see though, I suppose.

I agree that their Touch ID should be disabled, but is there some reason that's not possible?

If they got a message saying "Touch ID disabled" I'd say these people have no case.

But as it is, isn't this like making your iMac refuse to boot because you broke the DVD drive?

It's more like a car not starting because you tried a cheap knockoff key.

It's more like a car not starting because you tried a cheap knockoff key.

No. It's like the consumer uses a knockoff key and the manufacturer destroy the engine.

I agree that their Touch ID should be disabled, but is there some reason that's not possible?

If they got a message saying "Touch ID disabled" I'd say these people have no case.

But as it is, isn't this like making your iMac refuse to boot because you broke the DVD drive?

They are doing this to protect you, not as a "screw you for trying to fix your own phone." People will always see what they want to see though, I suppose.

Disabling Touch ID would protect them. What function does killing the OS serve over that?

Thanks for doing us this great service lawyer! Can't wait for my pennies while the lawyer gets the millions.