Security

Apple Watch usage with macOS

Auto Unlock with Apple Watch in macOS

Users with Apple Watch can use it to automatically unlock their Mac. Bluetooth Low Energy (BLE) and peer-to-peer Wi-Fi allow Apple Watch to securely unlock a Mac after ensuring proximity between the devices. This requires an iCloud account with two-factor authentication (TFA) configured.

When enabling an Apple Watch to unlock a Mac, a secure link using Auto Unlock Identities is established. The Mac creates a random one-time-use unlock secret and transmits it to the Apple Watch over the link. The secret is stored on Apple Watch and can only be accessed when Apple Watch is unlocked. The unlock token is not the user’s password.

During an unlock operation, the Mac uses BLE to create a connection to the Apple Watch. A secure link is then established between the two devices using the shared keys used when it was first enabled. The Mac and Apple Watch then use peer-to-peer Wi-Fi and a secure key derived from the secure link to determine the distance between the two devices. If the devices are within range, the secure link is then used to transfer the preshared secret to unlock the Mac. After successful unlock, the Mac replaces the current unlock secret with a new one-time use unlock secret and transmits the new unlock secret to the Apple Watch over the link.

Approve with Apple Watch

When Auto Unlock with Apple Watch is enabled, the Apple Watch can be used in place or together with Touch ID to approve authorization and authentication prompts from:

macOS and Apple apps that request authorization
Third-party apps that request authentication
Saved Safari passwords
Secure Notes

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Apple Platform Security

Apple Watch usage with macOS

Auto Unlock with Apple Watch in macOS

Approve with Apple Watch