I've run into issues with getting the various GnuPG email creation modules available to work. It looks like it is some change from GnuPG 1 to GnuPG 2. So I set out to write one out two simple functions to do this using MIME::Lite. One creates a email and one signs the body, if needed.

1: The creation function is invoked and checks if it it needs to use PGP.
2: If it is to use PGP, it passes the body to the signing function.
3: The signing function takes it and processes the body as follows...

$body="Content-Disposition: inline\n".
"Content-Transfer-Encoding: quoted-printable\n".
"Content-Type: text/plain\n\n".encode_qp($body);
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As the headers for the MIME section are required to be signed as well as the data, the headers that will be added later are tacked on in the form that MIME::Lite will use.

'encode_qp' is from 'MIME::QuotedPrint'.
4: This is then writen to the file and 'gpg2 -u '.$key.' --digest-algo SHA512 -a --detach-sign '.$bodyfile is ran.
5: $bodyfile.'asc' is then read in and returned the the creation function.
6: The email is then constructed...

$email=MIME::Lite->new(Type=>'multipart/signed');<br>
$email->attr('content-type.protocol'=>'application/pgp-signature');
$email->attr('content-type.micalg'=>'PGP-SHA512');
$email->attach('Content-Type'=>'text/plain', Encoding=>'quoted-printab
+le', Data=>$body);
$email->attach(Type=>'application/pgp-signature', Filename=>'signature
+.asc', Disposition=>'attachment',
 Encoding=>'7bit',Data=>$signed);
$email->add('To'=>$to);
$email->add('From'=>$from);
$email->add('From'=>$subject);
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8: The resulting object is then returned.

Please see the following for a example resulting string...

MIME-Version: 1.0
Content-Transfer-Encoding: binary
Content-Type: multipart/signed; boundary="_----------=_123721441885025
+0"; micalg="PGP-SHA512"; protocol="application/pgp-signature"
X-Mailer: MIME::Lite 3.024 (F2.77; T1.27; A2.04; B3.07; Q3.07)
Date: Mon, 16 Mar 2009 09:40:18 -0500
To: vvelox@vvelox.net
Subject: subject
From: v.velox@vvelox.net
Message-Id: <0.564867957585143.1237214418.ZConf::Mail@vixen42>

This is a multi-part message in MIME format.

--_----------=_1237214418850250
Content-Disposition: inline
Content-Transfer-Encoding: quoted-printable
Content-Type: text/plain

body

--_----------=_1237214418850250
Content-Disposition: attachment; filename="signature.asc"
Content-Transfer-Encoding: 7bit
Content-Type: application/pgp-signature; name="signature.asc"

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2.0.11 (FreeBSD)

iEYEABEKAAYFAkm+ZNIACgkQqrJJy0yxYQAu6ACfZLEAAiudAERIQ3seeuXBrhNq
0xUAniGRyHoxEonSGNjtDUJtdTs+1p0R
=C1pk
-----END PGP SIGNATURE-----

--_----------=_1237214418850250--
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