well. the thing is ... In the end i did the crypttab manually. but during "rescan devices" yast recognizes the encrypted disk. asks for the password. afterwards i format the the encrypted volume as lvm and use that. I cant do the crypttab before doing the lvm as i use it for my root volume. As yast recognizes the disk and yast uses the disk later; I would say a) yast is aware of the disk b) yast can the create the disk in the work flow after creating the rootfs.