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Why does iOS require a passcode (not Touch ID or Face ID) after reboot? Is passcode more secure?

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    Are you looking for the technical reason why a passcode is required or why Apple developed it so that it's required?
    – fsb
    Commented Jun 19, 2019 at 18:55
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    It is a security feature, keeps people who find a discharged phone, recharge it and try and get into it from doing so. Commented Jun 19, 2019 at 19:16
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    @SteveChambers If they aren't the owner of the phone, why would Face ID or Touch ID let them in?
    – clickbait
    Commented Jun 20, 2019 at 1:47
  • @SteveChambers nothing more secure about doing it this way, did you have a source for this reasoning? It's because biometrics can't actually work yet after boot before the enclave is decrypted with the pin. please refer to my answer which refers to an information security SE answer.
    – Wadih M.
    Commented Apr 18, 2023 at 14:18
  • I’m voting to close this question because asking why Apple does things is specifically off topic here. An edit is needed to ask a practical question based on the fact that Apple made a design / implementation choice and shipped it.
    – bmike
    Commented Apr 18, 2023 at 14:43

2 Answers 2

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Short Answer

Apple designed it thusly - the security subsystem in iOS hardware and software works.


Long Answer

User's biometric data is securely stored in a mathematical form in special hardware called Secure Enclave on iOS device. This data is not readable and never leaves the device. The Touch ID/Face ID subsystem do not have access to it.

When the device is locked, the Data Protection keys which are held in Secure Enclave are wrapped with a key that's given to the Touch ID or Face ID subsystem inside the Secure Enclave. When an unlock is attempted, if the device detects a successful match, it provides the key for unwrapping the Data Protection keys, and the device is unlocked.

But, when the device restarts, the keys required for Touch ID or Face ID to unlock the device are lost; they're discarded by the Secure Enclave.

Hence the device passcode is required to authentication the user.


To get a better sense of the iOS security design, you can refer to the iOS Security Guide, which is updated by Apple after major updates to iOS. The contents in the answer are derived from iOS Security Guide for iOS 12.3 released in May 2019.

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  • Thanks, I didn't know about that official security guide by Apple good to know!
    – Wadih M.
    Commented Apr 18, 2023 at 14:19
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It's because biometrics can't actually work yet before the fde is decrypted, which the pin is used to decrypt.

You may refer to below Information Security StackExchange answer that goes into depth why mobile devices have that behavior.

https://security.stackexchange.com/questions/134392/why-do-mobile-devices-force-user-to-type-password-after-reboot

Other mobile devices like Android have the same behavior.

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  • Apple surely could design this differently. Especially with the Secure Enclave and boot process / firmware design they implemented on iPhone and following devices.
    – bmike
    Commented Apr 18, 2023 at 14:20
  • @bmike Just answering OP's question on why he has to enter the pin each time he reboots. It's because the other features simply can't work yet. It's been thoroughly discussed on the referred link on information security SE. The question was not whether Apple could do it differently or not . There is nothing more secure about forcing to put a pin after a reboot, it's just required for the rest to work.
    – Wadih M.
    Commented Apr 18, 2023 at 14:23
  • I appreciate the link! The question has down votes too - it's not a great question since it's asking why Apple did something and not focusing on a practical problem. This question is likely to get closed TBH as it's not a good fit here.
    – bmike
    Commented Apr 18, 2023 at 14:42
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    @bmike not sure how an apple user's curiosity on why he has to enter his pin code after each boot is not a good question. He didn't ask why Apple did it this way. Where did you see that? And why is it not a good fit here I'm genuinely curious. What constitutes a good fit to be discussed here?
    – Wadih M.
    Commented Apr 18, 2023 at 14:51

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