Salesforce Authenticator 4.2.0 for iPhone

Salesforce Authenticator adds an extra layer of security to your online accounts as a strong, out-of-band authentication provider. The app sends you a push notification, and you tap 'Approve' for logins and critical actions when it's you, or 'Deny' if it's not. For even more convenience, Salesforce Authenticator can use location services to automatically verify from locations you trust, like your office or home. Better yet, Einstein can save trusted locations for you! Then you need only respond to notifications when something out-of-the-ordinary happens.

You can also get a verification code when you need one. The codes also work as a backup authentication method if you're on a plane, or have poor connectivity. This means Salesforce Authenticator also works with third-party services that use OATH TOTP tokens.
http://twofactorauth.org.

Continued use of GPS running in the background can dramatically decrease battery life. Rest assured, we go to great lengths to ensure minimal GPS use so that Salesforce Authenticator does not significantly impact your battery life.