On Thu, 21 Jul 2005, Thomas Roessler wrote:
DKIM works on entire message. EDigest always treats the data as
MIME part (or collection of MIME parts). There is quite a bit of
difference in what this means.
* OpenPGP (RFC-3156) does signing over the MIME encoded entity
(see Section 5), and not the original raw form.
* S/MIME (RFC-2633) does signing over the MIME encoded entity
(see Section 3), and not the original raw form.
In both of the above cases, both the original and the signature are
then enclosed in new entity and this new entity is what is transported
and may have its own different CTE.
Actually, no. RFC 2045, section 6.4:
Certain Content-Transfer-Encoding values may only be used on
certain media types. In particular, it is EXPRESSLY FORBIDDEN to
use any encodings other than "7bit", "8bit", or "binary" with any
composite media type, i.e. one that recursively includes other
Content-Type fields. Currently the only composite media types
are "multipart" and "message". All encodings that are desired
for bodies of type multipart or message must be done at the
innermost level, by encoding the actual body that needs to be
encoded.
That does not contradict what I said. It only limits the encodings that
can be used with composite media types (effectively not allowing to
use BASE64 and quoted-printable on multiparts).
But its fair to say that I did not remember that note from 2045 ...
--
William Leibzon
Elan Networks
william(_at_)elan(_dot_)net