I'm using the Expo Facebook login on my React Native app. In my app they can create and join events, which is done via API calls to my Laravel backend. I need these API calls to be authenticated (so some random person can't submit requests on someone else's behalf), but I don't want them to have to login twice. How can I ensure the person making API calls is who they say they are?
When they auth with Facebook they get their unique Facebook user ID, but I'm not sure if that is a secret they would only know after authenticating with FB or if anyone could get it. For my alpha version it's just sending their FB user ID with the request to ensure it's coming from the right person, but that seems really insecure because if anyone gets that ID they can forge requests.
One idea I had was to pass the auth token the React Native app got from Facebook to my API, and then on my server use that auth token to ensure it's really them. That just seems sort of complicated and it's hard to find a package that helps facilitate this, though.
It seems like this has to be a common problem. Any resources on how other apps handle this? Tinder, for example, must have this same problem.