Re: [Dcrup] I-D Action: draft-ietf-dcrup-dkim-usage-02.txt

[Scott Kitterman <[e-mail]>]

On Saturday, June 10, 2017 10:42:34 AM Martin Thomson wrote:
> I find the construction of this draft strange.  Why not simply say
> "verifiers MUST implement and use rsa-sha256 instead of rsa-sha1"?
> The remainder of the text is largely unchanged, which took me a while
> to validate.
> 
> The problem here is that removing the definition of rsa-sha1 is not
> the point.  The code point can't be undefined (Section 7 gets that
> right), and we don't really benefit from having the definition
> removed.  What we want is to have rsa-sha256 implemented and deployed.
> 
> So say two things, just to be perfectly clear:
> 
> 1. DKIM implementations MUST NOT rely on rsa-sha1, it's busted.
> 
> 2. DKIM implementations MUST use rsa-sha256.  Signers MUST create
> signatures using rsa-sha256 and verifiers MUST verify those
> signatures.

This is pretty much what we had in -01 and this approach was suggested 
instead.  In XML, sorry, here's the diff:

https://github.com/kitterma/draft-ietf-dcrup-dkim-usage/commit/b3956a026c18b88ac2f47f8a012610598149e286

I liked it better before, which is more like I believe you are suggesting, so 
let's see what others say on that particular topic.

> I disagree with John about the publication of this draft without the
> new schemes.  It's worth doing now and the extra overheads of
> publication are small.

Exactly.

> Nits:
> 
> Section 3, two errors here:
> > One algorithms, rsa-sha256, is currenlty defined.

Done.

> Section 3.2 s/,/ / here:
> > DKIM,[RFC6376]

Done.

> Section 6 has an extra period.

Fixed.

> Collapse Section 7.1 into Section 7:
> 
> """
> IANA is requested to update the "sha1" registration in the "DKIM Hash
> Algorithms" as follows:
> <table>
> """

Done.

snip.

Scott K