Re: [TLS] Consensus Call on draft-ietf-tls-dnssec-chain-extension

Nico Williams <> Thu, 05 April 2018 02:34 UTC

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Date: Wed, 04 Apr 2018 21:20:07 -0500
From: Nico Williams <>
To: Eric Rescorla <>
Cc: TLS WG <>
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Subject: Re: [TLS] Consensus Call on draft-ietf-tls-dnssec-chain-extension
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On Wed, Apr 04, 2018 at 07:22:38PM -0700, Eric Rescorla wrote:
> I don't think that this comparison is particularly apt.The
> representation in HSTS is simply "I support HSTS". The representation
> in HPKP is "I will use either consistent keying material *or* a
> consistent set of CAs". The representation here is "I will continue to
> have DNSSEC-signed DANE records". That is a significantly more risky
> proposition than continuing to support TLS (and I'm ignoring the risk
> of hijacking attacks that people were concerned with with HPKP), and
> so this seems rather more like HPKP to me.

Without a TTL (with zero meaning "clear the pin to DANE") this extension
can only really be used with mandatory-to-use-with-DANE protocols, where
the commitment to "continue to have DNSSEC-signed DANE records" is

The TTL allows one to put a bound on that commitment, thus alleviating
the risk.

That's the whole point: to alleviate the risk of commitment to DANE in
order to not discourage opportunistic deployment.