Re: [Dcrup] Is there anything this WG wants to do not yet in draft-ietf-dcrup-dkim-crypto-01 ?

Peter Goldstein <peter@valimail.com> Tue, 20 June 2017 21:01 UTC

Return-Path: <peter@valimail.com>
X-Original-To: dcrup@ietfa.amsl.com
Delivered-To: dcrup@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id CCEA01294DC for <dcrup@ietfa.amsl.com>; Tue, 20 Jun 2017 14:01:40 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -1.019
X-Spam-Level:
X-Spam-Status: No, score=-1.019 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, HTML_FONT_FACE_BAD=0.981, HTML_MESSAGE=0.001, RCVD_IN_DNSWL_NONE=-0.0001, SPF_PASS=-0.001] autolearn=no autolearn_force=no
Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (2048-bit key) header.d=valimail.com
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id ld2Ic9MVGMsQ for <dcrup@ietfa.amsl.com>; Tue, 20 Jun 2017 14:01:38 -0700 (PDT)
Received: from mail-qt0-x235.google.com (mail-qt0-x235.google.com [IPv6:2607:f8b0:400d:c0d::235]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 44E9A126D73 for <dcrup@ietf.org>; Tue, 20 Jun 2017 14:01:38 -0700 (PDT)
Received: by mail-qt0-x235.google.com with SMTP id u19so143289880qta.3 for <dcrup@ietf.org>; Tue, 20 Jun 2017 14:01:38 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=valimail.com; s=google2048; h=mime-version:in-reply-to:references:from:date:message-id:subject:to; bh=/rJP2ncG+igQrS84pBw/UpPX7162scmbNUIrOAqVXvA=; b=LIJ5NkbregZtqI5lj066MiNOIocbxU7+2uXKWMMqkhbjzJQzQpVpAb16niYEGiMH9H CB6TfNVKMXdXtZw4xFd4AxBWn5n8JOlvej7JNTzUAVvSG7w7POHnadRO7hT8nDveN/H3 8NP0FumIpqfr8j70jMWasbDaiU38dcFB4AUYAwaEHnMvRZ/GQaeSEp1ds83iFvC+k+FO +ssmCJHTGK8Cgqnx24uU+e4pLktElmZEAxaKAsat7yaq5Lq+uyxhiYl6N7h5kYdMKjFw Veat6tebUjXrdD1SqGF5RIymWA45D/J05k3so5KlmKf2VlwZbtRJAFOdWoDSIqUiFTPI MsjQ==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to; bh=/rJP2ncG+igQrS84pBw/UpPX7162scmbNUIrOAqVXvA=; b=lp32zhG9s6nJJiCYhplLFsbIFbkOfMTSK5MfvFr09zw4yu2OoKxPCXU774+HMteZl6 9um7OIKM8UBr42cnMtbkmf34jkIqAB3qrYRWET2rRiBnlyn78iBkWcwva0D6UdhjQHJI v6eskiU5oOH7GrFA2RXaz8Cw0JCNFr2hBD664eeGiMdKVnv4Qu2JIwcvcSU0i0lB7kQl ZqSaxDRWKFwuhJnX5l1511I5eAuAr1HUJ0WdubmfrEOSFWbj+M32U1iQx3WrocOhuaYa chqxK6eVBgbE33t5TN5zhAc72pX+HdHbXH0m0bf1as9prcCQU4dpLpIqe8daKt9fzFFb EQCA==
X-Gm-Message-State: AKS2vOyei99navHS3Rj1SSNUlDJspeAdRfXpnI1ynSJuX7U5hepTvIQa F8KqIxxfKqmXLFTQc21C6NgRiqdKLXl5EjU=
X-Received: by 10.200.55.233 with SMTP id e38mr35421253qtc.198.1497992497277; Tue, 20 Jun 2017 14:01:37 -0700 (PDT)
MIME-Version: 1.0
Received: by 10.12.175.183 with HTTP; Tue, 20 Jun 2017 14:01:36 -0700 (PDT)
In-Reply-To: <1669306.WDH1r8A93p@kitterma-e6430>
References: <alpine.OSX.2.21.1706121103510.19565@ary.local> <10416754.S7IJN86VGL@kitterma-e6430> <alpine.OSX.2.21.1706201544520.36769@ary.qy> <1669306.WDH1r8A93p@kitterma-e6430>
From: Peter Goldstein <peter@valimail.com>
Date: Tue, 20 Jun 2017 14:01:36 -0700
Message-ID: <CAOj=BA0r5=cx_zKr-V2CVyuGd7_LKn_CtbjK4UEwuVh=RKCFXg@mail.gmail.com>
To: Scott Kitterman <sklist@kitterman.com>, dcrup@ietf.org, "John R. Levine" <johnl@iecc.com>
Content-Type: multipart/alternative; boundary="001a113e4180ad3cff05526a8eef"
Archived-At: <https://mailarchive.ietf.org/arch/msg/dcrup/rsBCedCTIjXGtUOggbO6bgfK060>
Subject: Re: [Dcrup] Is there anything this WG wants to do not yet in draft-ietf-dcrup-dkim-crypto-01 ?
X-BeenThere: dcrup@ietf.org
X-Mailman-Version: 2.1.22
Precedence: list
List-Id: DKIM Crypto Update <dcrup.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/dcrup>, <mailto:dcrup-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/dcrup/>
List-Post: <mailto:dcrup@ietf.org>
List-Help: <mailto:dcrup-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/dcrup>, <mailto:dcrup-request@ietf.org?subject=subscribe>
X-List-Received-Date: Tue, 20 Jun 2017 21:01:41 -0000

The -02 document looks basically good to me.

The new EdDSA and fingerprinting behavior seems well-defined and
unambiguous.  And the guidance on minimum key length seems fine.  And the
SHA-1 language is clear and unambiguous.

My only question is whether there's any need or desire to support larger
RSA key sizes (e.g. 4096)?  I don't know of a use case that requires such
support that couldn't be met by the use of EdDSA, but I wanted to make sure
the question was considered by the WG.

Best,

Peter

On Tue, Jun 20, 2017 at 1:13 PM, Scott Kitterman <sklist@kitterman.com>
wrote:

> On Tuesday, June 20, 2017 04:01:18 PM John R. Levine wrote:
> > > I think it's still not clear where the group lies on how dead we should
> > > kill rsa-sha1.  I think the WG chairs are going to have to evaluate the
> > > consensus and let us know.  Once that's done, converging on the correct
> > > wording should be ~easy (whether it ends up in my draft or John's).
> >
> > Given that we are not the Network Police, I don't see this as a very
> > meaningful questions We can tell people not to sign with sha-1 or to
> > verify sha-1 signatures, but we can't threaten them with penalties if
> they
> > ignore us.
> >
> > In practice, the known problems with sha-1 aren't yet very relevant to
> > short lived signatures like DKIM's since the cost of finding a collision
> > remains high, so signers can't be bothered to upgrade their signers.  I
> > looked at the last 1000 signed messages I got from non-spam bulkish
> > mailers, and 354 of them still had sha1 signatures.  They can't be
> > bothered to upgrade, and the IETF has no leverage.
> >
> > At some point I expect one of the big gorillas will decide to stop
> > accepting sha-1 and after a week of panic in the bulk mail community,
> > they'll all patch their signers and we'll never see another sha-1
> > signature again.
>
> Right, and when the panic happens (which is, I agree, when this will change
> for real) I'd like for the engineer getting beat up by his boss to be able
> to
> say in response to the "Argh! What should be do" question from the PHB [1]
> "We
> need to upgrade our DKIM like it says in RFC XXXX" [2].  I think what
> you've
> proposed covers that.
>
> Scott K
>
>
> [1] The pointy haired boss (see Dilbert), not the other one.
> [2] Followed by a mostly silent "Like I've been telling you for a year."
>
> _______________________________________________
> Dcrup mailing list
> Dcrup@ietf.org
> https://www.ietf.org/mailman/listinfo/dcrup
>



-- 


[image: logo for sig file.png]

Bringing Trust to Email

Peter Goldstein | CTO & Co-Founder

peter@valimail.com
+1.415.793.5783