# File lib/googleauth/service_account.rb, line 193
      def new_jwt_token jwt_aud_uri, options = {}
        now = Time.new
        skew = options[:skew] || 60
        assertion = {
          "iss" => @issuer,
          "sub" => @issuer,
          "aud" => jwt_aud_uri,
          "exp" => (now + EXPIRY).to_i,
          "iat" => (now - skew).to_i
        }
        JWT.encode assertion, @signing_key, SIGNING_ALGORITHM
      end