Liferay and WebSphere SSO (simplistic)

Since Liferay is providing CAS (Central Authentication Service) support its possible to access Liferay through WebSphere SSO (LTPA tokens) login credentials.
So what to do?
I can not post all of our source code because of "some security" issues :-)
Steps:
1. Edit portel-ext.properties (or portal-impl.jar//portal.properties)
1.1 Add/Edit the CAS configuration lines
##
## CAS
##
cas.auth.enabled=true
#
cas.import.from.ldap=false
#
cas.login.url=/portal/cas-web/login
cas.logout.url=/portal/html/common/was_logout.jsp
cas.service.url=/portal/c/portal/login
cas.validate.url=/portal/cas-web/proxyValidate

The bold lines say Liferay where to login or logout

2. Create Java-Classes for decrypting the WebSphere LTPA-Token
Have a look at these examples
http://blog.offbytwo.com/2007/08/21/working-with-lightweight-third-party-authentication-ltpa/
http://offbytwo.googlecode.com/svn/trunk/bitsandpieces/LTPAUtils/

and copy them to WEB-INF/classes/ (or pack them into a jar-file)

3. Add AutoLogin-Classes (Step 2) to portal-ext.properties
auto.login.hooks=,com.liferay.portal.security.auth.CASAutoLogin,...

4. Add was_logout.jsp to specify the cas-logout-path (see step 1)
Content (example):

<%@ page import="java.util.*" %>
<%@ page import="com.liferay.portal.util.*;" %>

<%-- auto-submitted by javascript --%>

5. Create new Sign in portlet or edit the delivered sign in portlet
Content of view.jsp (example):
<% if (!themeDisplay.isSignedIn()) { %>

<%-- /*

">" method="post" name="fm"> */ --%>
fm">

	submit" value="">

<% } %>

6. Add Login-config to web.xml
...

FORM
PortalRealm

/c/portal/j_login
/portal/web/guest/login/error


...

Thats it

Workflow:
User logs in > LTPA-Token cookie is created by WebSphere > Custom AutoLogin-Class is called > Custom AutoLogin-Class reads Cookies > Custom AutoLogin-Class decrypts LTAP-Token from Cookie > Custom AutoLogin-Class returns credentials array
Example:
credentials[0] = String.valueOf(user.getUserId());
credentials[1] = user.getPassword();
credentials[2] = boolean.TRUE.toString();
> Liferay accepts login