------------------------------------,
Fixed Header            = 8         |
Message                 = 4         |
  ---------------------,            |
  Name                 |  4 +       |
    NameSegments        = 4n +      |
                       |  comps_n   |
  ---------------------'            |
  ExpiryTime            = 12         = 124 + 4n + comps_n + clen
  Payload               = 4 + clen  |
  ---------------------,            |
  ValidationAlgorithm  |            |
    T_HMAC-256          = 56        |
      KeyID            |            |
    SignatureTime      |            |
  ---------------------'            |
  ValidationPayload     = 36        |
------------------------------------'