Re: [Dcrup] I-D Action: draft-ietf-dcrup-dkim-usage-00.txt

[Scott Kitterman <[e-mail]>]

On Monday, June 05, 2017 01:18:13 PM Murray S. Kucherawy wrote:
> On Mon, Jun 5, 2017 at 9:53 AM, Scott Kitterman <[e-mail]>
> 
> wrote:
> > I hear you.  I expect this to be the most contentious part of the draft.
> > 
> > Here's my counter argument:
> > 
> > The first DKIM RFC (RFC 4871), published in 2007 said:
> > > Signers MUST implement and SHOULD sign using rsa-sha256
> > 
> > I believe that the only reason rsa-sha1 was included at all was to make
> > transition from domainkeys easier (see RFC 4870).  That's also (as I
> > understand it where the 512 bit minimum key size came from).
> 
> As I recall, there were also implementations of DKIM made during its
> development (even before its IETF time) that supported both, and defaulted
> to rsa-sha1 because support for SHA256 in OpenSSL was new and not
> universally deployed.  Some of them were still running in the wild, and
> SHA1 wasn't fully deprecated, so the choice was made to be inclusive while
> encouraging use of the newer stuff as much as possible.
> 
> > As a working group document editor, I'll change it however the group wants
> > (of
> > course), but I think we should either kill rsa-sha1 entirely in this
> > document
> > or leave it out entirely and let one of the follow-on documents add a new
> > algorithm and remove rsa-sha1.  Preferably a clean kill or, failing that,
> > not
> > at all is what I think we should do.
> 
> I would omit it from the updated version entirely, and mark it "obsolete"
> in the registry.
> 
> -MSK, from the floor

How about this (rfcdiff attached)?

Scott K