Re: [DNSOP] New Version Notification for draft-pwouters-powerbind-00.txt (fwd)

Michael Casadevall <> Tue, 20 March 2018 13:19 UTC

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From: Michael Casadevall <>
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Date: Tue, 20 Mar 2018 09:19:06 -0400
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Subject: Re: [DNSOP] New Version Notification for draft-pwouters-powerbind-00.txt (fwd)
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On 03/20/2018 07:44 AM, Paul Wouters wrote:
> The goal of the document is to make such malicious changes visible.
> If the parent needs to replace NS/DS records, these are easily
> auditable identically to Certificate Transparency (rfc 6962bis)
> We only need to look (log) the DS/DNSKEY and we do not have
> to monitor all TLSA and other security RRtypes. Without this flag,
> we need to track and log every DNS RRtype that has public key material
> in it.

Forgive my ignorance on the subject, but I'm having trouble following
how delegation_only flag actually helps in this specific case.

Certificate Transparency works because specifically because the entire
certificate is uploaded, and (assuming a valid cert) a SCT is generated
which can be verified by cross-checking it against the log servers
public key.

Without the RRtypes logged, I'm not seeing how you're supposed to be
able to audit them. In the case where a KSK is compromised, you could
simply sign a new zone record, serve up fraudulent records and remain
unaware. CT as it's implemented in the x509 world (combined with
Expect-CT) specifically prevents unknown but validly signed certificates
from being used.

I'm likely missing something obvious, by only logging DS/NS, it would be
impossible to determine if a private key is misused to serve fraudulent
records which in my mind is a bigger and much more likely/common threat
since one can simply attack a target domain and not try to compromise
the root.

Moving to the topic of the draft itself:

>From a technical point of view, aren't there TLDs that as authoritative
for second level domains as well? The specification likely needs a way
to denote how many levels deep delegation can go. This also would be
true in the case of delegation_only being used at a level above both the
root and TLD zones.

I know historically .name only allowed registration of third-level
domains until 2009, and .uk up until 2014. I'm unsure if any of the TLDs
still restrict and/or is authoritative for second-level domains as well.

At a minimum though, the one case I know off hand of a TLD being
authoritative for a second-level domain is that ICANN requires new gTLDs
are required to publish a wildcard for 90 days when they're added to the
root zone to help catch any name collisions.