Re: [Ietf-dkim] Question about lone CR / LF

[John Levine <[e-mail]>]

It appears that Murray S. Kucherawy  <[e-mail]> said:
>-=-=-=-=-=-
>
>On Wed, Jan 31, 2024 at 5:44 PM Steffen Nurpmeso <[e-mail]> wrote:
>
>> But i cannot read this from RFC 6376.
>
>Sections 2.8 and 3.4.4 don't answer this?

Not really.  They say what to do with CRLF but not with a lone CR or lone LF.

RFC5322 says:

   o  CR and LF MUST only occur together as CRLF; they MUST NOT appear
      independently in the body.

So I think the answer is that a thing with a lone CR or LF is not a
valid message so signers shouldn't sign them and validators shouldn't
validate them. If you want to allow them, OK, but no promises that
anyone at the other end will treat the brokenness the same way you
dod.

We can get into some theological arguments about BINARYMIME which
allows arbitrary bytes in a MIME part but I expect that DKIM
canonicalization code will choke on other stuff in binary MIME before
it gets to a \x0a or \x0d.

R's,
John