認証をFirebase Authenticationに丸投げし、そちらで作ったトークンをサーバーに送信、認可を行う時に有効 FIREBASE_PROJECT_ID = "FIREBASEPROJECTID" CIRTIFICATE_URL = 'https://www.googleapis.com/robot/v1/metadata/x509/securetoken@system.gserviceaccount.com' EXP_LEEWAY = 30.seconds VALID_ISS = "https://securetoken.google.com/#{FIREBASE_PROJECT_ID}" CERTIFICATE_MAP = JSON.parse(Net::HTTP.get_response(URI.parse(CIRTIFICATE_URL)).body) TokenVeri