+------------+
   +--------+         |            |
   |Operator|         | Directory  |
   +--------+         |   Server   |
                      +------------+
+----------------+  +----------------+
| +-----------+  |  |  +-----------+ |
| |   Fetch   |  |  |  |           | |
| |  Device   |<------>|Certificate| |
| |Certificate|  |  |  |           | |
| +-----+-----+  |  |  +-----------+ |
|       |        |  |                |
| +-----v------+ |  |                |
| |  Encrypt   | |  |                |
| |   Device   | |  |                |
| |   Config   | |  |                |
| +-----+------+ |  |                |
|       |        |  |                |
| +-----v------+ |  |                |
| |  Publish   | |  |                |
| |    TFTP    | |  |                |
| |   Server   | |  |                |
| +------------+ |  |                |
|                |  |                |
+----------------+  +----------------+