of course it's possible, but it's not a feature of the SDK for now.
Which means you have to do it on your own.
In one of your other threads i gave you a pointer to XEP-0116 encrypted sessions. This XEP is hardly under development in the XMPP Standards Foundation and the way to go for eSessions once it's finished. I know that encrypted sessions are on our Roadmap. You have to contact Alex for more details.