Subject: Re: [POSH] [dane] while we're waiting for DANE deployment...

From: Peter Saint-Andre <[email-masked]>
Date: Fri, 21 Jun 2013 09:39:06 -0600

[ + [email-masked] - I will drop [email-masked] if this thread continues ]

On 6/21/13 8:23 AM, Viktor Dukhovni wrote:
> On Thu, Jun 20, 2013 at 08:02:45PM -0600, Peter Saint-Andre wrote:
> 
>> DANE is awesome and will solve many practical challenges with
>> the existing PKI (e.g., the inability to securely offer proper 
>> certificates for hosted domains in multi-tenanted environments).
> 
> Isn't this *supposed* to be solved via SNI?  (I personally don't 
> believe SNI scales, but I'm willing to go along with the idea for 
> argument's sake now and then).

The core problem in the PKI context is that BigCompany.com isn't going
to hand over its private keys to ConvenientHostingService.com, and the
hosting company doesn't want those keys anyway for liability purposes.

> Is it no longer controversial to say that SNI does not solve the 
> multi-tenant problem?  If so, then I'd like to more strongly 
> emphasise my comments on DANE and CNAMEs.  If DANE clients chase 
> CNAME RRs (while keeping track of DNSSEC validation at each step), 
> then multi-tenant deployments can avoid SNI depedence, as the TLSA 
> RRs would only need to be published in one place by the service 
> operator.  Otherwise, it is not clear how DANE addresses the 
> multi-tenant issue.

With POSH we are trying to find an interim solution to PKI issues. I
*think* (although I have not yet proved it out) that DANE solves those
problems, too. But the PKI problems are pressing enough that we need
to solve them as soon as possible.

>> Unfortunately, DANE won't be widely deployed anytime soon. (As
>> one example, we're still struggling with the lack of DNS SRV
>> support among domain registrars for certain major TLDs, let alone
>> DNSSEC support.)
> 
> Is the main obstacle in your view lack registrar infrastructure to 
> support customer DNSSEC deployment, or lack of tools for customers 
> to manage DNSSEC zone signing?

IMHO, probably both. But I will ask some folks on the operational side
to find out more.

>> https://datatracker.ietf.org/doc/draft-miller-posh/
>> 
>> As the abstract says:
>> 
>> This document defines two methods that make it easier to deploy 
>> certificates for proper server identity checking in application 
>> protocols.  The first method enables a TLS client to obtain a
>> TLS server's end-entity certificate over secure HTTP as an
>> alternative to standard Public Key Infrastructure using X.509
>> (PKIX) and DNS-Based Authentication of Named Entities (DANE).
>> The second method enables a source domain to securely delegate an
>> application to a derived domain using HTTPS redirects.
> 
> This requires TLS clients to also also implement HTTPS, and to
> able to do PKIX validation of HTTPS peers.

Yes, but we figure that such code is very widely available.

> Plus additional latency to fetch the certs via HTTPS with no local
> cache (as with DNS).  This certainly looks unappealing from an SMTP
> perspective.

A happy eyeballs approach should help with latency.

>> Feedback from folks in the DANE community is very much welcome on
>> the [email-masked] list:
>> 
>> https://www.ietf.org/mailman/listinfo/posh
> 
> I'll take a closer look when I get a chance, but I am skeptical.

Your skepticism is appreciated.

> New standards take a long time from inception to wide adoption. 
> Software released today takes ~2-5 years to be included by O/S 
> distributions (if bundled as with MTAs) or upgraded by a majority 
> of the user base.  Browsers with their independent distribution 
> channels are the exception, not the rule.  So I think that
> deployment barriers today should not overly prejudice architectural
> decisions for software that will only become mainstream in ~5
> years.

That is a valid point, and one that we'll need to consider at the BoF
in Berlin.

Pete

- -- 
Peter Saint-Andre
https://stpeter.im/

---

From: Guido Witmond <[email-masked]>
Date: Fri, 21 Jun 2013 18:50:56 +0200

> That is a valid point, and one that we'll need to consider at the BoF

That's a good argument to work on browser plugins. Like the ridiculed
Extended DNSSEC validator. Or the next version of CZ.nic's original plugin.

Even if the only purpose of these tools is to raise awareness about
DNSSEC/DANE, I believe it's worth it.

My authentication protocol relies on DANE, so I made it into a browser
proxy. [1]

Regards, Guido.

[1] http://eccentric-authentication.org/blog/2013/06/07/run-it-yourself.html

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From: Jesse Thompson <[email-masked]>
Date: Tue, 25 Jun 2013 23:08:58 -0500

On 6/21/13 10:39 AM, Peter Saint-Andre wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
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+1 (especially in light of Prism)

> IMHO, probably both. But I will ask some folks on the operational side

Talking with the network folks in my organization... little hope of 
DNSSEC any time soon.

Jesse
University of Wisconsin

---

From: Peter Saint-Andre <[email-masked]>
Date: Tue, 25 Jun 2013 23:31:39 -0600

> Talking with the network folks in my organization... little hope of

Unfortunately that's the experience of many many people. Thus the
impetus some of us feel to work on POSH...

Peter

-- 
Peter Saint-Andre
https://stpeter.im/