Re: [dns-privacy] how can we ADoT? (with github url)

Tony Finch <> Thu, 12 November 2020 00:00 UTC

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Date: Thu, 12 Nov 2020 00:00:53 +0000
From: Tony Finch <>
To: Manu Bretelle <>
cc: DNS Privacy Working Group <>
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Subject: Re: [dns-privacy] how can we ADoT? (with github url)
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Manu Bretelle <> wrote:
> Totally fair, pretty sure there were no speaker notes ;) . The
> presentation is available at .
> Originally, there was this draft
> and the solutions in the slide deck were compiled from feedback/ideas that
> came up while talking with other folks.

Ooh, that video has lots of ideas, thanks! I think most of them are
slightly different angles on approaches that I rejected in my notes. (how
do I do a wry emoticon?) I'll try to summarise - please forgive me if I
have misunderstood...

  * DSPKI: vaguely dnscurve flavoured delegations, but putting an X.509
    SPKI into a new delegation RRtype. Comes under my "new kind of
    delegation" heading.

    (There's a twist that DSPKI seems to have an authenticator per zone,
    so all servers are expected to share the same private key?)

  * Do9: per-server encryption hint without authenticator inside DS
    records. Most of the badness under my "new DS algorithm" heading,
    but with less key rollover churn. WebPKI authentication.

Joe Abley emphasized what I called the scalability issue. Wes Hardaker
made a slightly different point about correctness and synchronization of
apex and delegation records. Wes's point kind of strengthens the
scalability issue: a design that avoids per-zone configuration of any
kind for scalability reasons also avoids delegation mismatch problems.

Watson Ladd made a good point about decoupling signalling from
authentication. My prejudice was that if you are publishing a 1 bit ADoT
signal in the DNS you might as well publish a 256 bit authenticator; now
that I have gone through the options in detail I still think that is true.
And I think it implies that any approach to ADoT based on in-band
signalling should avoid relying on any records published in the DNS,
because then the in-band signal no longer does anything useful.

[ I've been very bad at looking for and citing previous work, sorry
everyone... I belatedly realise the datatracker doesn't list expired
drafts, oops ]

> Speaking of which, I think Brian Dickson did a good job of describing an
> "hybrid" approach which I had notes of, but never got to write down
> properly. Here is the link:

Yes, I think Brian's description is basically the same as what I have in
mind. On top of that I've added a little complication, `dot--` hints so
that when a delegation requires glue, a resolver can still connect
directly over TLS without first getting the TLSA records. I am unsure if
these hints are really needed...

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