Message-ID: <54CA467B.30408@gnome.org>
Date: Thu, 29 Jan 2015 09:40:59 -0500
From: Jeffrey Stedfast <fejj@gnome.org>
User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64;
	rv:31.0) Gecko/20100101 Thunderbird/31.4.0
MIME-Version: 1.0
To: David Bremner <david@tethera.net>, gmime-devel-list@gnome.org
Subject: Re: [gmime-devel] gmime and S/MIME
References: <87twz9wyf8.fsf@maritornes.cs.unb.ca>
In-Reply-To: <87twz9wyf8.fsf@maritornes.cs.unb.ca>
Content-Type: text/plain; charset=windows-1252; format=flowed
Content-Transfer-Encoding: quoted-printable
Cc: notmuch@notmuchmail.org
Precedence: list

Hi David,

On 1/29/2015 7:42 AM, David Bremner wrote:
> With a few others, I've been attempting to get S/MIME supported in
> notmuch (which as you might or might not remember is using gmime
> underneath). The signature verification part is working OK, but I've
> gotten a bit bogged down trying to get decryption working.
>
> What I have learned is that according RFC5751, smime message (parts)
> look like
>
>     Media type:  application/pkcs7-mime
>     parameters:  any
>     file suffix: any
>
>     Media type:  multipart/signed
>     parameters:  protocol=3D"application/pkcs7-signature"
>     file suffix: any
>
>     Media type:  application/octet-stream
>     parameters:  any
>     file suffix: p7m, p7s, p7c, p7z
>
> Unless I miss something, out of the box there is only support for
> decrypting multipart/encrypted.  In particular the gmime tests for
> S/MIME use this "container format" [1].

Correct, I don't think I ever got around to implementing the=20
GMimeApplicationPkcs7Mime class.

>
> So I'm wondering if I'm confused about the RFC(s), or about GMIME, or i=
s
> one suppose to write analogs of g_mime_multipart_encrypted_decrypt for
> other top level parts?

You are not confused. I would probably hesitate to say that it was my=20
*intention* for everyone to implement their own S/MIME class for=20
pkcs7-mime, but in any case, that is what needs to be done right now :(

FWIW, I've written another library called MimeKit in C# which shares a=20
similar design to GMime that is hosted on GitHub that implements the=20
pkcs7-mime class:

https://github.com/jstedfast/MimeKit/blob/master/MimeKit/Cryptography/App=
licationPkcs7Mime.cs

Hopefully that helps provide you with ideas on how to implement the same =

sort of thing using GMime for notmuch.

(btw, if you end up implementing this, I'd love to accept your patches=20
into GMime proper)

Jeff