Re: [dbound] draft-brotman-rdbd

"John R. Levine" <johnl@iecc.com> Mon, 01 April 2019 02:00 UTC

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Date: 31 Mar 2019 22:00:10 -0400
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From: "John R. Levine" <johnl@iecc.com>
To: "Stephen Farrell" <stephen.farrell@cs.tcd.ie>
Cc: dbound@ietf.org
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Subject: Re: [dbound] draft-brotman-rdbd
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On Mon, 1 Apr 2019, Stephen Farrell wrote:

> For example, if a relying-party has seen the same public key used for a 
> relating domain N times or for N years, and sees that public key used 
> again, then that relying-party can treat that differently, compared to a 
> public key just seen now, without any DNSSEC. ...

> That trust-model for signatures is entirely as was done for DKIM.

Well, there's the problem -- this is completely different from the trust 
model for DKIM.

For one thing, DKIM associates a key in the DNS with signatures in 
messages.  The DKIM key is public but the message isn't.  In this design, 
both ends are in the DNS and both are public.

More to the point, although I realize that a lot of DKIM signers never 
rotate their keys, that is universally agreed to be bad practice.  I 
rotate my DKIM keys every month, so you'll never see a key record of mine 
for more than about seven weeks (a month plus some slop at each end.)  I 
would be pretty surprised if anyone considered a DKIM key record more 
credible because it had been around for a long time.

Regards,
John Levine, johnl@iecc.com, Primary Perpetrator of "The Internet for Dummies",
Please consider the environment before reading this e-mail. https://jl.ly