FirebaseUI - using recaptcha with email sign-in method

Question

I want to add a captcha functionality to my FirebaseUI email-based login to make it more difficult for bots and other abusers to log into my app.

I have investigated these:

1. This link describes how to add a captcha to FirebaseUI when signing-in with a phone number but in my app I use the email signin method. I have tried doing the same for the email method:

   signInOptions: [
     {
        provider: authconst.EmailAuthProvider.PROVIDER_ID,
        recaptchaParameters: {
          type: 'image', // 'audio'
          size: 'normal', // 'invisible' or 'compact'
          badge: 'bottomleft' //' bottomright' or 'inline' applies to invisible.
        },
      },
   ],
   

But this wont trigger the recaptcha. How can I link the recaptcha to the email signing method?

2. This link describes how to add recatcha to an app, but I need to link it to the sign-in method otherwise a bot could just bypass the catcha and trigger the sign-in making the captcha useless. How can I validate the captcha token response server-side? Are there some Cloud Function libraries to do that?

Answer 1

Recaptcha verification is only available in the Phone provider for Firebase Authentication. There is no way to configure it for the email+password provider, and FirebaseUI is not set up to include a recaptcha in the email+password flow either.

If you want to require the users to sign in with email+password and require them to solve a recaptcha, you'll have to build that yourself.