Gnus mishandled PGP clearsigned files in attachments

[Juliusz Chroboczek <jch@pps.jussieu.fr>]

Hi,

(I've also reported this as Debian bug 348383 -- sorry for the spamming.)

Gnus mishandles ASCII-armored GPG signed files sent as attachments.
An example of such a file is available on gmane in group
gmane.comp.version-control.darcs.devel under

  Message-ID: <200601142043.k0EKhTvU018182@ms-smtp-02.nyroc.rr.com>

There are two mis-behaviours:

  - when displaying such a message, Gnus will attempt to verify the
    signature before de-QP-ing.  Obviously, this fails;
  - when saving such an attachment, Gnus discards the PGP armour (and
    therefore the signature).  This makes it impossible to check the
    signature.

Mutt simply treats the attachment as plain text:

  - when displaying such a message, Mutt doesn't attempt to do any
    processing.
  - when saving such an attachment, Mutt saves the pristine, de-QP-ed
    attachment, which it is then possible to verify.

Ideally, Gnus would behave like Mutt when saving the attachment, but
verify the signature after de-QP-ing when displaying the message.

(In case you're interested: there are very good reasons for using this
sort of attachments -- the attachment can be verified after being
saved without using a mailer, which is not the case with PGP/MIME.
This is a needed feature in Darcs.)

Thanks for your help,

                                        Juliusz Chroboczek