def METHOD_NAME(self, key: str, dt: str):
    k_date = self.sign(("OSC4" + key).encode("utf-8"), dt)
    k_region = self.sign(k_date, self.connection.region_name)
    k_service = self.sign(k_region, self.connection.service_name)
    return self.sign(k_service, "osc4_request")