0     8     16    24    32    40    48    56
+-----+-----+-----+-----+-----+-----+-----+-----+
|          SIZE         |    ZONE TYPE          |
+-----+-----+-----+-----+-----+-----+-----+-----+
|                  ZONE KEY                     /
/                  (BLINDED)                    /
|                                               |
+-----+-----+-----+-----+-----+-----+-----+-----+
|                   SIGNATURE                   |
/                                               /
/                                               /
|                                               |
+-----+-----+-----+-----+-----+-----+-----+-----+
|                   EXPIRATION                  |
+-----+-----+-----+-----+-----+-----+-----+-----+
|                    BDATA                      |
/                                               /
/                                               /
+-----+-----+-----+-----+-----+-----+-----+-----+