In an IQHandler, how to get the authenticated user that sent it?

I want to implement an IQHandler, but I want to make sure that only authenticated users can send IQ Packets to it. I want to make sure that the JID I get from Packet.getFrom() is the authenticated user that sent it.

I need this so that no one can just create an IQ Packet and set the “from” attribute to a user id other than their own. Can someone help me with this?