使用 PGP/MIME 签署多部分邮件

Question

我正在尝试在 php 中使用 PGP 签署邮件。我可以使边界和标题正常工作，但邮件签名无效（如 Thunderbirds Enigmail 所述）。

我这里的问题是要签什么部分，签的时候要注意什么。

目前生成邮件的来源是这样的（文本和签名被占位符替换以保持易于阅读）：

Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=_1b5364229a82b654fad7cf2aa969f02e"
MIME-Version: 1.0

This is a message in Mime Format.  If you see this, your mail reader does not support this format.

--=_1b5364229a82b654fad7cf2aa969f02e
Content-Type: multipart/alternative;
  boundary="=_53ba9ef8c471e6c8d72f215feaad8033"
Content-Transfer-Encoding: 7bit


--=_53ba9ef8c471e6c8d72f215feaad8033
&Content-Type: text/plain; charset=UTF-8
&Content-Transfer-Encoding: quoted-printable
&
&PLAIN TEXT CONTENT ENCODED IN QUOTED PRINTABLE
& 
&--=_53ba9ef8c471e6c8d72f215feaad8033
&Content-Type: text/html; charset=UTF-8
&Content-Transfer-Encoding: quoted-printable
& 
&HTML CONTENT ENCODED IN QUOTED PRINTABLE

--=_53ba9ef8c471e6c8d72f215feaad8033--

--=_1b5364229a82b654fad7cf2aa969f02e
Content-Type: application/pgp-signature; name="signature.asc"
Content-Disposition: attachment; filename="signature.asc"
Content-Description: OpenPGP digital signature

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.11 (GNU/Linux)

PGP SIGNATURE HERE
-----END PGP SIGNATURE-----

--=_1b5364229a82b654fad7cf2aa969f02e--

目前以 & 开头的行用于生成签名。换行符只是换行符 (PHP_EOL)。

我尝试遵循 RFC2015 但这似乎不适用于多部分/替代内容。

请帮我解决这个问题。

Answer 1

我发现自己...

首先，我需要将所有换行符转换为 CRLF，就像 RFC 状态一样。然后我需要将整个 multipart/alternative 包括其标题视为要签名的消息。所以应该是：

Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=_1b5364229a82b654fad7cf2aa969f02e"
MIME-Version: 1.0

This is a message in Mime Format.  If you see this, your mail reader does not support this format.

--=_1b5364229a82b654fad7cf2aa969f02e
&Content-Type: multipart/alternative;
&  boundary="=_53ba9ef8c471e6c8d72f215feaad8033"
&Content-Transfer-Encoding: 7bit
&
&
&--=_53ba9ef8c471e6c8d72f215feaad8033
&Content-Type: text/plain; charset=UTF-8
&Content-Transfer-Encoding: quoted-printable
&
&PLAIN TEXT CONTENT ENCODED IN QUOTED PRINTABLE
& 
&--=_53ba9ef8c471e6c8d72f215feaad8033
&Content-Type: text/html; charset=UTF-8
&Content-Transfer-Encoding: quoted-printable
& 
&HTML CONTENT ENCODED IN QUOTED PRINTABLE
& 
&--=_53ba9ef8c471e6c8d72f215feaad8033--

--=_1b5364229a82b654fad7cf2aa969f02e
Content-Type: application/pgp-signature; name="signature.asc"
Content-Disposition: attachment; filename="signature.asc"
Content-Description: OpenPGP digital signature

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.11 (GNU/Linux)

PGP SIGNATURE HERE
-----END PGP SIGNATURE-----

--=_1b5364229a82b654fad7cf2aa969f02e--

以 & 开头的行是要签名的行。