How to decript the acs from HTTP-Redirect in Java

Hi, I.m using the delivered SDK Java adapter for the communication and proces of the response to and from Signicat broker al is wel but I also want to use the
“urn:oasis:names:tc:SAML:2.0:bindings:HTTP-Redirect” wich sent a SAML repononse in the query parm.
I have been searchingal around but till now no luck.
Is there somewhere a repo I can use as example?
Regards Sam.