thirdpartysig;
  sig=*MEYCIQCNxJzn6Rh2fNxsobktir8TkiaJYQFhWTuWI1i4PewQaQIhAMs2TVjc4rTshDtXbgQEOwgj2mRXALhfXPztXgPupii+=*;
  integrity="mi";
  validity-url="https://thirdparty.example.com/resource.validity.1511161860";
  cert-url="https://thirdparty.example.com/certs";
  cert-sha256=*UeOwUPkvxlGRTyvHcsMUN0A2oNsZbU8EUvg8A9ZAnNc=*;
  date=1511133060; expires=1511478660