Apple Platform Security Guide updated with Unlock with Apple Watch, Magic Keyboard details...

Posted:
in General Discussion edited May 2021
Apple has updated its Platform Security Guide, providing more information about how the Unlock with Apple Watch feature in iOS 14.5 and Touch ID on the iMac Magic Keyboard works.

Credit: AppleInsider
Credit: AppleInsider


The company routinely updates the security guide to incorporate information about new features. The Platform Security Guide contains detailed and in-depth information about Apple's privacy and security mechanisms.

For example, the update on Monday sheds new light on the secure channel between the Magic Keyboard with Touch ID and the Secure Enclave in an M1 iMac.

Before a Magic Keyboard is able to unlock a Mac, Apple says that it needs to be securely paired to the machine. Apple says the Secure Enclave in the iMac and the PKA block in the Magic Keyboard exchange public keys and use other cryptographic mechanisms to attest to their identities. Once a pair is successful, it encrypts all traffic between the two devices.

According to Apple, that channel is "established in the factory by using a unique key shared between" the iMac and the keyboard. Apple says it's the same mechanism that's used to create a channel between a Secure Enclave and a built-in fingerprint sensor.

Apple has also offered new details on the cryptography behind the Unlock with Apple Watch feature in iOS 14.5, which allows users to more easily unlock an iPhone with Face ID if they're wearing a mask. There's also new information about the security parameters that govern the use of the feature.

The feature uses the same mechanism as auto unlock for Mac. The guide states that a mutually authenticated station-to-station (STS) protocol that uses long-term keys that are established when the feature is enabled. Once two devices are paired, unique and ephemeral keys are negotiated for each unlock request.

Apple says the tunnel is negotiated directly between the Secure Enclave is both devices. That means all cryptographic material is kept within that secured box.

The distance between the two devices must also be two to three meters or less. An iPhone must also have been unlocked at least once since the Apple Watch was placed on a user's wrist and unlocked. The Apple watch must not be in bedtime mode, and sensors must be able to determine whether the nose and mask of the user are covered.

The last update to the Platform Security Guide came in February. At the time, Apple expanded the guide to nearly 200 pages and added features about Apple Silicon, car key security, and password monitoring, as well as information about Apple's Security Research Device program.

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Comments

  • Reply 1 of 6
    SaGrLandSaGrLand Posts: 1member
    "that channel is "established in the factory by using a unique key shared between" the iMac and the keyboard."
    So it is not possible to buy and/or pair the keyboard with an M1 MacBook without getting Apple involved?
    watto_cobra
  • Reply 2 of 6
    mknelsonmknelson Posts: 1,125member
    SaGrLand said:
    "that channel is "established in the factory by using a unique key shared between" the iMac and the keyboard."
    So it is not possible to buy and/or pair the keyboard with an M1 MacBook without getting Apple involved?
    The article seems to be paraphrasing and leaving out some details:

    https://support.apple.com/en-ca/guide/security/secf60513daa/1/web/1

    Apple performs the pairing process in the factory for a Magic Keyboard with Touch IDthat is shipped with a Mac. Pairing can also be performed by the user if needed. A Magic Keyboard with Touch ID can be securely paired with only one Mac at a time, but a Mac can maintain secure pairings with up to five different Magic Keyboard with Touch ID keyboards.
    bageljoeydoozydozenwatto_cobra
  • Reply 3 of 6
    GeorgeBMacGeorgeBMac Posts: 11,421member
    I updated both my watch and iPhone to the latest release.   But the unlock procedure has not changed -- the iphone has to see my full face.

    Do I need to set a switch or something to activate this?
    I liked how the watch can unlock my (now deceased) MacBook and would love it if it did the same for my iPhone.
  • Reply 4 of 6
    nicholfdnicholfd Posts: 824member
    I updated both my watch and iPhone to the latest release.   But the unlock procedure has not changed -- the iphone has to see my full face.

    Do I need to set a switch or something to activate this?
    I liked how the watch can unlock my (now deceased) MacBook and would love it if it did the same for my iPhone.
    Yes you do:  Settings app -> Face ID & Passcode -> UNLOCK WITH Apple Watch -> Toggle on.
    GeorgeBMacwatto_cobra
  • Reply 5 of 6
    GeorgeBMacGeorgeBMac Posts: 11,421member
    nicholfd said:
    I updated both my watch and iPhone to the latest release.   But the unlock procedure has not changed -- the iphone has to see my full face.

    Do I need to set a switch or something to activate this?
    I liked how the watch can unlock my (now deceased) MacBook and would love it if it did the same for my iPhone.
    Yes you do:  Settings app -> Face ID & Passcode -> UNLOCK WITH Apple Watch -> Toggle on.

    Thank you!
  • Reply 6 of 6
    crowleycrowley Posts: 10,453member
    Ugh, why is the Unlock with Watch feature restricted to Series 3 or above Apple Watches?  I can unlock my Mac with my Series 2 watch, but not my iPhone?  Total nonsense Apple.
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