If you ever need to get your Touch ID-enabled home button repaired, be sure to have it done by Apple Authorized Service Providers or Apple directly only: UK newspaper
The Guardian reports that "thousands" of users who have had their Touch ID button repaired by third parties and found that their iPhone
would then "brick" itself (become inoperative) after the next iOS update. The notorious "Error 53" that causes this, according to Apple, is a security measure to prevent low-level hardware hacking.
"We protect fingerprint data using a Secure Enclave, which is uniquely paired to the Touch ID sensor," said an Apple spokesperson in response to complaints from users. "When [an] iPhone is serviced by an authorized Apple service provider or Apple retail store for changes that affect the Touch ID sensor, the pairing is re-validated. This check ensures the device and the iOS features related to Touch ID remain secure. Without this unique pairing, a malicious Touch ID sensor could be substituted, thereby gaining access to the secure enclave. When iOS detects that the pairing fails, Touch ID, including Apple Pay, is disabled so the device remains secure."
Unauthorized technicians do not have access to the validation procedure, which can lead to the Error 53 problem when users update the OS. Apple's recommendation for users having problems with the home button is to contact Apple to arrange an authorized repair, by mail if necessary due to the users' location.
The only solution to an iPhone that has been bricked by the unauthorized repair is to replace the iPhone, since the unit cannot be recovered even through a reset or restoration. Apple has said that it goes to elaborate lengths to protect the user's fingerprint and financial data encrypted in the "secure enclave" of it processor, and that the Error 53 problem is intended to fight off the possibility of hardware hacking or modification of the Apple fingerprint sensors, which could result in identity theft and more.
Repair firm iFixit, in an unusual move, sides with Apple in saying that the reason for the issue are to ensure that only genuine components are being used so as to prevent malicious hardware modifications. "Once a third party changes the home button or internal cable, the iPhone checks to be sure that all original components are running the phone, and if there are any discrepancies users face the "error 53" message and can't access their data," iFixit's Kyle Wiens told the newspaper.
While sending an iPhone away (possibly to another country) for repair can be a challenge for users in remote or other areas where Apple doesn't have a strong presence, due to the sensitive information unlocked by the home button, unauthorized repairs have the potential to put users at risk of irreversible theft of data.
MacNN recommends that users who need home-button repairs done on an iPhone 5s or higher (or Touch ID-enabled iPads) contact Apple before having the repairs done in order to explore options that would allow the fix to be done securely.