Windows Unlock is one of the most eagerly-awaited new Windows 10 features that will arrive in the Anniversary Update later this year. But now some newly-released Microsoft documentation explains how it will work.
We first became aware of this feature over the weekend, when a separate set of documentation, aimed at IT pros, was discovered. In its Windows 10 Roadmap, Microsoft revealed the following:
Use Companion Devices to unlock your Windows PC. Use your Microsoft Band 2, or other devices that integrates with the Windows 10 Companion Device Framework (CFD), as companion device for Microsoft Passport based authentication. With this a device like the Microsoft Band 2 or other third party devices, they can become an external second factor of authentication which can be used to unlock your Windows 10 PCs.
Use your phone to unlock your Windows PC. Use your Windows Phone or Android phone as remote credential store which can be used to unlock any of your Windows 10 PCs and authenticate with apps and services that support Windows Hello and Microsoft Passport based authentication.
Now, [MSDN—Microsoft’s web site for developers—provides more information about this feature](Windows Unlock with companion devices), which is collectively called Windows Unlock. The idea is that a user should be able to seamlessly and securely sign in to a PC even when a Windows Hello-based authentication device is not present. Instead, you can use another device you have with you—your smart phone or a wearable—to authenticate you.
This can work via a surprising range of device types.
Via USB. Here, you attach the companion device to the PC via USB, touch the button on the companion device, and automatically unlock the PC.
Smart phone. In this scheme, you pair your smart phone with your PC using Bluetooth. When you dismiss the lock screen on the PC, a notification will appear on the phone. Approve it and the PC unlocks.
NFC. To unlock the PC, tap a companion device to an NFC reader.
Wearable. Using a fitness or other wearable, you can perform a special gesture (like clapping) in front of the PC, and it will unlock.
The MSDN document also describes the three “signals” that Windows Unlock supports. For a Windows Unlock device to authenticate the user, one of more of these signals must be delivered.
Intent signal. This allows the user to show his intent for unlock by, for example, hitting a button on the companion device. The intent signal must be collected on companion device side, MSDN notes.
User presence signal. This proves the presence of the user. The companion device could, as an example, require a PIN before it can be used for unlocking the PC. (This PIN is separate from the PC PIN.) Or it might require press of a button.
Disambiguation signal. This helps to disambiguate which Windows 10 PC the user wishes to unlock when there are multiple options on the companion device.
It looks like Windows Unlock will work with the other Windows Hello/Windows Passport scenarios that will be supported in the Anniversary Update, too. That means you should be able to use Windows Unlock to authorize purchases in Windows Store, sign-in to web sites with Edge, and more.