Emacs Gnus email decrypt smime without openssl

Question

I use gnus for my email. Every once in a while, I receive an encrypted email; when I answer "yes" to Gnus offer to decrypt it, it responds smime-verify-region: No CA configured. Now, my workplace doesn't allow any OpenSSL stuff, so I've been hoping to get it working with pgp. But the instructions at http://www.emacswiki.org/emacs/GnusSMIME don't seem fully cogent to me. I've made sure I have gpg installed, and I've added the suggested lines:

;; SMIME in .gnus
(require 'epa-file)
(epa-file-enable)
(setq epg-debug t)

(setq mm-decrypt-option 'always)
(setq mm-verify-option 'always)
(setq gnus-buttonized-mime-types '("multipart/encrypted" "multipart/signed"))
(setq mml-smime-use 'epg)

and I've also added the suggested lines to newly created gpg.conf and gpgsm.conf files (they did not exist previously, although gpg was installed). But I still get the same error when I try to read the encrypted emails. What am I actually supposed to do? How can I decrypt smime in Gnus without openssl?

Note: I do not use BDB (I use org-contacts instead)

GNU Emacs 24.3.1 (x86_64-redhat-linux-gnu, GTK+ Version 3.10.9) of 2014-05-21 on buildvm-07.phx2.fedoraproject.org Gnus v5.13