Is there a way to encrypt the passwords in the $NCHOME/guiserver/install/nci_client.xml and $NCHOME/impact/install/new-server.xml files?
There's no way to encrypt the passwords for the "wasadmin" user in the $NCHOME/guiserver/install/nci_client.xml and $NCHOME/impact/install/new-server.xml files. What you can do is not change the passwords in those files, as you'll only need to use those files when creating a new server instance, installing fixes, or running the $NCHOME/guiserver/install/ncgui_createear utility. So be sure to modify those files with the correct plain text password first, if you're doing any of those procedures mentioned above, whenever you're finished just set the password back to the old password, or a bogus password, or no password at all.
This is no longer an issue on Impact 6.1.