USB encrypted persistence on Ubuntu - Xubuntu 1804 custom live iso

Ok I know how its done with debian but debian uses live-boot which already has the feature where in Ubuntu it used capser I need to patch capser to make it ask for password of an encrypted persistent casper-rw file and mount it as persistence storage I followed this link [login to view URL] then modified my install xubuntu but after building the iso it only asks for password but it won't mount it for persistence Don't offer me to work on this project if you have't done this before its not a game and I won't even repy if i see a general proposal! u need to show me that u really understand how to do it on an installed Xubuntu and when I build the iso it should work !