Java Security

I am developing a application which is going to do some Single Sign-On authentication. This application is going to be a J2SE application for the desktop.

For those who do not know what Single Sign-On is: For user who have multiple usernames and password for different web site, Single Sign-On offers them a way to authenticate to these different site without the need to remember all those passwords. It takes over the authentication process, and authenticates to these web sites for the user. The usernames and passwords are stored in a database.

I am going to develop such a program in Java. This program is going to fetch the web site which contains the login form. Find out what to send to the web server. Send the username and password stored for that web site and in return if authentication goes through the web site will send the web page to the Java program which when receive it will open it in a web browser.

Does anyone have any idea how I can implement this Single Sign-On feature? I know there exist several applications for windows which offers such Single Sign-On and which works with Internet Explorer. So somehow I should be able to make such a feature for a Java application.