The app is used with Google's two-factor authentication service to make logging in to Google accounts more secure.
TechCrunch reports that users who don't have a trusted computer will need to reset their all stored tokens on Google that allow other services like Dropbox or Evernote to connect to users' Google accounts.
Updating the app removes all your existing accounts, with users complaining in reviews for the update that they’ve lost their Dropbox, Google Apps, DreamHost, Twilio, Evernote and other tokens after updating and have been forced to sync each over again. It could leave you locked out of your accounts entirely and forced to contact support for a reset, as Dashlane’s co-founder Alexis Fogel tells us is happening with his service, and it’s something that will also result in an awful lot of unnecessary busy work to set up things that have already been set up before.The update points to a larger potential problem with iOS 7, where app updates will download automatically onto iOS devices. MacRumors has heard from several iOS 7 beta testers who lost their account info on Google Authenticator because the update was downloaded automatically when it was released.
iOS 7 users do have the option to revert to the manual update scheme used in prior versions of iOS.
There is no word from Google on when the app will be updated and returned to the App Store. The update also includes a new design with a flat icon to match Apple's iOS 7 look-and-feel.
Google Authenticator is normally available free from the App Store. [Direct Link]