How Does the Authenticator App Work on iPhone?
Logging into any service or a website with a 2FA a user provides a login and password(something that he knows). Then the website or service generates a required code but doesn’t show it to the user. Then the user runs the KeepSolid Authenticator app, which independently computes and displays the same password (something that you have). The user enters it and authenticates his identity for the app. That’s it!