Ralph, Again, use the button reply to list. Disk encryption don't use gpg. You just have to remember a pass pharase that you use for unlock your hard disk.
Installer will overwrite all your disk, but if you want you can skip this step by pressing "cancel" button please learn what gpg is and what is luks and use the reply to list button. https://wiki.archlinux.org/index.php/disk_encryption
