JAAS, Java Authentication & Authorzation Service, is a component-based
framework that allows pluggable implementations of Authentication and
Authorization policies and technologies.  Yes, I intend to use JAAS.

However, Single SignOn begins when someone signs onto the Network
and/or OS.  I want to pick up the Network or OS credentials and forward
them to

Once a user has signed on Windows,  what Credentials are available?

Credentials uniquley identify the user and authenticate the user.

How do I access or read those credentials so that I can forward them
with subsequent requests for Application Services and Functions which
is where Authorization will be performed.