OS X El Capitan, iOS 9 get new two-factor authentication system
Apple's operating system-level two-factor authentication system will kick in whenever you sign in on a new device or Web browser with your Apple ID. You'll have to enter a six digit code along with your password as a way to help keep unauthorized people from accessing your Mac, iPhone, iPad, or iPod touch.
The six digit code will be delivered to devices running iOS 9 or OS X El Capitan you have already confirmed as trusted. Logging into a new Mac, for example, will send a unique login code to your iPhone. You then enter that code on your Mac to access your data.
Apple says this is different from the two-step verification system already in place in iOS 8 and OS X Yosemite. According to Apple, “It uses different methods to trust devices and deliver verification codes, and offers a more streamlined user experience.”
Since people forget their passwords, Apple will have a system in place to help people get back into their two-factor enabled devices if their login information slips their mind. Apple will review forgotten password attempts on a case-by-case basis, and if they decide your request is legit you'll get instructions for the reset process. That's the good news; the bad news is that it may take a couple days before you get that notification.
Apple will offer its new two-factor authentication system with the public betas for OS X El Capitan and iOS 9. Not everyone will have access to the feature right away, and Apple said, “Individual accounts will be made eligible gradually until we can offer the service to everyone.”
If you're already using two-step authentication Apple says you should hold off on trying out two-factor authentication until both operating systems is available to everyone, which sounds a lot like code for transitioning from two-step to two-factor authentication isn't working exactly right yet.
The public betas will be available soon. You can sign up to participate at Apple's beta software website.