code: func Hash(certificate *x509.Certificate) string {
  	spkiHash := sha256.Sum256(certificate.RawSubjectPublicKeyInfo)
  	return formatSHA256 + ":" + strings.ToLower(hex.EncodeToString(spkiHash[:]))
  }
docs: // Hash calculates the SHA-256 hash of the Subject Public Key Information (SPKI)
  // object in an x509 certificate (in DER encoding). It returns the full hash as a
  // hex encoded string (suitable for passing to Set.Allow).