If the .gnupg directory is owned and only writable by root, then you must run the cpan install as root, which you'd normally have to do anyway, in order to get things installed in the correct location. It sounds like you've got some non-standard setup. In which case I'm not likely to be able to help you. Sorry. :-(
In reply to Re^3: bad gpg
by thargas
in thread bad gpg
by cmac