+---------------------------------------+
                | - Verify client request message.      |
                | - Extract TLS key material.           |
                | - Generate KE response message.       |
                |   - Include Record Types:             |
                |       o NTS Next Protocol Negotiation |
                |       o AEAD Algorithm Negotiation    |
                |       o <NTPv4 Server Negotiation>    |
                |       o <NTPv4 Port Negotiation>      |
                |       o New Cookie for NTPv4          |
                |       o <New Cookie for NTPv4>        |
                |       o End of Message                |
                +-----------------+---------------------+
                                  |
                                  |
Server -----------+---------------+-----+----------------------->
                  ^                      \
                 /                        \
                /    TLS application       \
               /     data                   \
              /                              \
             /                                V
Client -----+---------------------------------+----------------->
            |                                 |
            |                                 |
            |                                 |
+-----------+----------------------+   +------+-----------------+
|- Generate KE request message.    |   |- Verify server response|
| - Include Record Types:          |   |  message.              |
|  o NTS Next Protocol Negotiation |   |- Extract cookie(s).    |
|  o AEAD Algorithm Negotiation    |   +------------------------+
|  o <NTPv4 Server Negotiation>    |
|  o <NTPv4 Port Negotiation>      |
|  o End of Message                |
+----------------------------------+