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Re: [TLS] Dnsdir early review of draft-ietf-tls-svcb-ech-01

Rob Sayre <sayrer@gmail.com> Sat, 30 March 2024 18:02 UTC

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From: Rob Sayre <sayrer@gmail.com>
Date: Sat, 30 Mar 2024 11:01:59 -0700
Message-ID: <CAChr6SwoKqvrsKbm-K3vK793sn0p1WR2wky8cJSR-JbHytEBiA@mail.gmail.com>
To: Erik Nygren <erik+ietf@nygren.org>
Cc: Ted Lemon <mellon@fugue.com>, Eric Rescorla <ekr@rtfm.com>, dnsdir@ietf.org, draft-ietf-tls-svcb-ech.all@ietf.org, tls@ietf.org
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Subject: Re: [TLS] Dnsdir early review of draft-ietf-tls-svcb-ech-01
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On Sat, Mar 30, 2024 at 10:47 AM Erik Nygren <erik+ietf@nygren.org> wrote:

>
> An attacker who can prevent SVCB resolution can deny clients any
> associated security benefits.
>
>
Yes.


> A hostile recursive resolver can always deny service to SVCB queries, but
> network intermediaries can often prevent resolution as well, even when the
> client and recursive resolver validate DNSSEC and use a secure transport.
> These downgrade attacks can prevent a client from being aware that "ech" is
> configured which would result in the client sending the ClientHello in
> cleartext.
>
>
I think s/would/could/ here.

I don't know if we want to write it, but doesn't using encrypted transport
DNS to an IP address avoid this problem? Like using 1.1.1.1 or 8.8.8.8 etc.
I know that raises centralization issues, but it does help with this issue.

thanks,
Rob

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