Available in beta for Google and Google Cloud accounts.
Two-step authentication (also referred to as 2SV or 2FA) is one of the best tools you can use to add an extra layer of protection to your online accounts. Getting 2SV codes via a text message or an authenticator app is great, but if you want to go an extra step further, you can use physical keys in order to access your data.
As of April 10, 2019, you can now use your Android device (running Android 7.0 or later) as a physical 2SV key for your Google and Google Cloud accounts.
Once enabled, you'll get a prompt on your chosen Android device to approve your login any time you try to sign into your Google account. When you see this prompt, you can approve the login by holding the volume down button or tapping "No, it's not me" on your display if it's not you logging into your account.
You'll need Bluetooth turned on on your phone in order for this to work, and just in case something goes wrong, it's also recommended that you have another security key as a backup.
This feature is currently in beta, and in addition to requiring an Android phone, you'll also need a Bluetooth-enabled Chrome OS, macOS X, or Windows 10 machine running Google Chrome.
To use it, all you need to do is enroll your Google account is 2SV, go to the 2SV settings on your computer, click "Add security key", and choose your Android phone from the list of devices.
Two-factor authentication: Everything you need to know