Firebase authentication with custom token

问题:

I have a firebase project which Im trying to authenticate from my rails server creating a custom token with the library ruby-jwt as it says on the docs, but i keep getting the same error:

auth/invalid-custom-token, The custom token format is incorrect. Please check the documentation.

The credentials.json is from the service account I made in google console, uid is sent from the front end to the api.

def generate_auth_token(uid)
  now_seconds = Time.now.to_i
  credentials = JSON.parse(File.read("credentials.json"))
  private_key = OpenSSL::PKey::RSA.new credentials["private_key"]
  payload = {
      :iss => credentials["client_email"],
      :sub => credentials["client_email"],
      :aud => 'https://identitytoolkit.googleapis.com/google.identity.identitytoolkit.v1.IdentityToolkit',
      :iat => now_seconds,
      :exp => now_seconds+(60*60), # Maximum expiration time is one hour
      :uid => uid.to_s,
      :claims => {:premium_account => true}
    }
  JWT.encode(payload, private_key, 'RS256')
end

it looks like this in jwt.io

{
  "iss": "[e-mail]",
  "sub": "[e-mail]",
  "aud": "https://identitytoolkit.googleapis.com/google.identity.identitytoolkit.v1.IdentityToolkit",
  "iat": 1486824545,
  "exp": 1486828145,
  "uid": "4",
  "claims": {
     "premium_account": true
   }
}

回答1:

Please, take a look at my firebase_id_token gem.
It does exactly what you want.

回答2:

I found a better way to authenticate, I'm just sending the token that firebase gives you and verifying it on rails with the information I need and that's it.