Re: [dns-privacy] [Ext] Re: ADoT requirements for authentication?

Ted Hardie <ted.ietf@gmail.com> Tue, 29 October 2019 16:01 UTC

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From: Ted Hardie <ted.ietf@gmail.com>
Date: Tue, 29 Oct 2019 09:01:21 -0700
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To: Paul Hoffman <paul.hoffman@icann.org>
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Subject: Re: [dns-privacy] [Ext] Re: ADoT requirements for authentication?
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Hi Paul,

On Tue, Oct 29, 2019 at 8:27 AM Paul Hoffman <paul.hoffman@icann.org> wrote:

> On 10/29/19 8:02 AM, Ted Hardie wrote:
> > To be sure I understand you correctly, in the second case, the
> connection would be made to some IP address (e.g. NASA's 198.116.4.181).
> The recursive resolver logs the details of the certificate, but it
> continues with the connection even if the CA NASA uses for the certificate
> is not known to the resolver?  What does it do in the face of other
> certificate errors like expired certificates or certificates presenting a
> different name?
>
> It continues. This is exactly how opportunistic encryption is defined.
>
>
Just to be clear, it's my experience that accepting self-signed
certificates from peers does not equate to accepting certificate errors.
The situation in which you set up a connection to n.n.n.n and get a self
signed certificate saying "example.com" and when you set up a connection to
n.n.n.n expecting "example.com" and get a cert back for "accident.example"
are pretty distinguishable. I would expect some configurations to accept
the first without issue; I find accepting the second deeply odd.


> > I have to say that I'm pretty surprised by the idea that TLS in this
> context should behave any differently than TLS in application layer
> contexts, and I'm a little concerned about having configuration options for
> this that amount to "ignore errors of types $FOO".
>
> TLS in application layers can specify that opportunistic encryption, yes?
>
>
I think you are using "opportunistic encryption" to mean something
different from what I mean by it.  What I mean by it is "use it when you
can, even if you don't know in advance you can".  Testing for DoT before
using a DNS resolver on UDP 53 and using it if you find it is
"opportunistic encryption", for example.


> >  Accepting self-signed certificates is a known configuration, so I get
> that, but if someone has configured roots of trust, accepting other
> certificates outside the roots of trust in the configuration is pretty odd
> practice.
>
> Do you feel that there is a requirement that all recursive resolvers use
> the same set of trust anchors?


No.


> If not, and if you are against the use of opportunistic encryption in this
> case,


See above.  I don't think I'm against opportunistic encryption.  I think
I'm against starting to exchange traffic over a TLS connection with an
identifiable error.  There are degrees there, obviously.  Some folks would
say an expired but correct certificate should be logged but accepted, but a
flat out "wrong name presented" would likely get different treatment.

who will decide what set of trust anchors all resolvers in all
> jurisdictions will use?
>
>
Everyone will decide who they accept?  That's how the WebPKI works, for all
its shuffling glory, and with ACME/Let's Encrypt it has gotten very easy to
get a certificate that will often be accepted.

Just my two cents,

Ted

--Paul Hoffman
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