Mutt: Decrypting inline gpg format directly

[Mathias Bauer]

Hello,

* Heinz Diehl wrote on Fri, 18 Jul 2014, at 20:59 (+0200):

> On 18.07.2014, The Fuzzy Whirlpool Thunderstorm wrote:
>
> > I wonder if Mutt can be configured to decrypt inline pgp
> > messages automatically, without piping the attachment to `gpg
> > --decrypt`.
>
> You can't. Put this into your .procmailrc. It'll transform your
> inline pgp mails accordingly:
>
> :0
> * !^Content-Type: multipart/encrypted
> {
>        :0 fBw
>        * ^-----BEGIN PGP MESSAGE-----
>        * ^-----END PGP MESSAGE-----
>        | formail \
>           -i "Content-Type: application/pgp; format=text;
> 	  x-action=encrypt"
> }
>
> :0
> * !^Content-Type: multipart/
> {
>        :0 fBw
>        * ^-----BEGIN PGP SIGNED MESSAGE-----
>        * ^-----BEGIN PGP SIGNATURE-----
> * ^-----END PGP SIGNATURE-----
>        | formail \
>           -i "Content-Type: application/pgp; format=text;
> 	  x-action=sign"
> }

There are several points worth considering before using the above
procmail recipes:

a) The latest Mutt-GnuPG-PGP-HOWTO is quite old (Feb 2000) [1].
b) RFC3156, which defines PGP/MIME, originates from Aug 2001 [2].
c) The current procmail v3.22 has some issues with the B flag [3].

and most important

d) You can't catch all curiosities automatically.

Therefore I suggest using some modified/extended recipes instead:

:0
* ! ^Content-Type:[ \t]+message/
* ! ^Content-Type:[ \t]+multipart/
* ! ^Content-Type:[ \t]+application/pgp
{
  :0 f w
  * B ?? ^-----BEGIN PGP MESSAGE-----
  * B ?? ^-----END PGP MESSAGE-----
  |formail -b -f -i 'Content-Type: application/pgp; format=text; x-action=encrypt'

  :0 f w
  * B ?? ^-----BEGIN PGP SIGNED MESSAGE-----
  * B ?? ^-----BEGIN PGP SIGNATURE-----
  * B ?? ^-----END PGP SIGNATURE-----
  |formail -b -f -i 'Content-Type: application/pgp; format=text; x-action=sign'
}

But as Bob already mentioned, further details should better be
discussed on mutt-users at mutt.org.

Regards,
Mathias

[1] http://tldp.org/HOWTO/Mutt-GnuPG-PGP-HOWTO-8.html
[2] http://www.ietf.org/rfc/rfc3156.txt
[3] http://pm-doc.sourceforge.net/doc/#flags_hb_at_top_of_recipe_warning

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