First off, who is the diagram for? And what are you trying to communicate with it?
UC diags are typically used to dscribe Users (Actors) and what they want to achieve (Use Cases). They don't focus on how the user's goals are facilitated.
Your question focuses primarily on the technology; the only discernable Use Case is "Authenticate" for the "User" Actor. That doesn't seem particularly insightful. Developing this line of thinking, the next question would be: why does the User need to be authenticated? i.e. what can he/she do once successfully authenticated? And are those things in scope for your system? Relatedly, authentication commonly comes with a set of companion UCs: registering in the first place (e.g. setting name, pwd, memorable data), resetting / retrieving lost pwd, etc.
The above all assumes you're really trying to communicate who the users are and what they need to do. It may be that's not your purpose; maybe you want to communicate the solution design (User accesses application, app sends message to server, etc.). If so then you're probably better served with sequence diagram(s) and/or component diagrams.
Note the two aren't mutually exclusive: solution design naturally flows from user needs. So it may be both are applicable. All depends on what you want to communicate.
hth.
