In the "Diagnostic and Data Usage " section on my "Settings " app for my iPhone
It has "Apple.extentions"
What does it mean
In the most basic terms, a SSL Handshake is an agreement for connection parameters between the device and the server it is connecting to. Were you around during the days of 56k? Remember that crunching, electronic-gibberish sound the modem/computer would make when connecting to the internet? That's the sound of "handshaking".
I'm not 100% sure, but I'm guessing the SSL handshake in your iPhone's Diagnostic and Data report is just pointing out when your phone connects with a server and what data is sent.
The Diagnostic and Data Usage section are just a bunch of text logs of System Events that occur on your iOS device. The log isn't necessarily tracking your actions, but more creating entries when events such as an app crash occurs.