Apple’s Federighi explains the security behind auto-unlocking your Mac with your Apple Watch

“One of the more exciting new software features Apple introduced with macOS Sierra is Auto Unlock, a feature that allows users wearing an Apple Watch to quickly unlock their Mac and bypass the pesky password prompt altogether,” Yoni Heisler reports for BGR.

“During a recent episode of The Talk Show podcast, John Gruber of Daring Fireball brought up the issue of Auto Unlock security with Craig Federighi, Apple’s senior VP of Software Engineering,” Heisler reports. “Gruber asked Federighi what security mechanisms Apple incorporated to make the feature truly secure.”

“How will Apple ensure that a Mac will not be continuously unlocked just because its owner happens to be nearby?” Heisler reports.

Read how measuring distance at the speed of light is integral to your Apple Watch being able to securely unlock your Mac in the full article here.

MacDailyNews Take: It’s secure.

[Thanks to MacDailyNews Readers “Fred Mertz” and “Davey” for the heads up.]


  1. The unique challenge with auto-unlock is that you don’t want a kind of relay-attack, where Phil is actually well far away from his office and someone basically has a bluetooth listener that will forward a signal to you, because you’re now by his Mac, and this Mac is having a conversation with Phil’s watch over a very long distance. And so, we’re actually able to do time of flight calculations using peer-to-peer Wi-Fi where we literally can measure how long at the speed of light it’s taking for the signal to travel from your Mac to your watch and back.

    Too kewl.

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