Google is expanding the ability to use an Android phone as a physical two-factor authentication security key to include iOS devices (the feature previously launched in April, but only worked with Chrome OS, macOS, or Windows 10), as noted by 9to5Mac.
Due to limitations on how iOS works, the process is slightly different here: instead of using Chrome to communicate with the device (as used for the PC versions), the Android phone links up with Google’s Smart Lock app instead.
The net result is that once it’s all set up, when you log into your Google account on an iOS device, the app is able to ping the Android phone over Bluetooth. Then, users can confirm that they are, in fact, the one trying to log in on the Android device, which relays that information back to the iOS device, and allows the login to proceed.
Given that security key support for iOS devices has been somewhat limited, adding the option to use an Android phone makes the enhanced security feature much more accessible. Google envisions that the setup would be used by someone with, say, an iPad and an Android phone, which makes sense. But there’s no reason why one couldn’t use this with an iPhone, too, assuming you carry around two phones.
The new feature should be available today on all Google accounts.