Eli5: How does the an authenticator app (like Google authenticator) and a site I’m accessing communicate if my authenticator app is in an offline phone?

Question

To expound, I access a website that has a 2FA that asks me a temporary authentication code generated by Google authenticator. My Google authenticator is in my Android phone, which is usually offline. Even so, the temporary code that it generates still works when I input it in the website.

How does that work? How does my Google authenticator in a phone that isn’t connected to the net communicate with the website?

In: Technology

Answer 1

I’m sorry, theirs a few ways to do this, You’d have to describe what you do with the phone and the app to use it in offline mode to narrow down which is used in this case.

but if your inputting a code into some device that your phone generated for you, then the answer is that code is sent to google and *some math* is done on it, the result of which validates you as the person who has access to the authorised phone, and google confirms to the site your Authorised.