Microsoft is planning to enable two-factor authentication for Microsoft Accounts sometime soon. Read more about it here. Authenticator app for Windows Phone devices is a companion app that generates security codes that you can use to help keep your Microsoft account secure.
The Authenticator app generates security codes you can use to help keep your Microsoft account secure. You can add your Microsoft account to the app by scanning a barcode or by manually entering a secret key. The app implements industry-standard security code generation and may also work with other services and providers. You can learn more about keeping your Microsoft account secure at https://account.live.com/p.
Download it here from Windows Phone Store for free.