Re: [dane] CT for DNSSEC

Wei Chuang <weihaw@google.com> Fri, 17 March 2017 16:31 UTC

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From: Wei Chuang <weihaw@google.com>
Date: Fri, 17 Mar 2017 09:31:44 -0700
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To: Paul Hoffman <paul.hoffman@vpnc.org>
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Subject: Re: [dane] CT for DNSSEC
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On Thu, Mar 16, 2017 at 10:25 AM, Paul Hoffman <paul.hoffman@vpnc.org>;
wrote:

> On 16 Mar 2017, at 10:09, Wei Chuang wrote:
>
> I saw there was significant interest
>> <http://blog.huque.com/2014/07/dnssec-key-transparency.html> in exploring
>> CT for DNSSEC back in 2014 of which a draft draft-zhang-trans-ct-dnssec
>> <https://tools.ietf.org/html/draft-zhang-trans-ct-dnssec-03> was created.
>> It seems to have quieted down since.  I believe the motivation is still
>> there which is to prevent a parent zone from potentially misbehaving and
>> spoofing the child zone.  Is there still interest in this?  From the list
>> archives, I can't see what the issues were though I'm guessing one of them
>> was respecifying the DS resource record to use a SCT which might have
>> caused compatibility concerns.  (But please correct me if I'm wrong)
>> Other
>> than that, the draft seems pretty reasonable.  Were there other concerns?
>>
>
> There were two separate issues that got conflated at the time:
>
> - Seeing evidence that a parent had spoofed DNSSEC keys for a child. A
> transcript of the DS records in the parent is sufficient as long as the
> child doesn't have relying parties create islands of trust (which is
> relatively rare these days).
>
> - Seeing evidence that a parent had spoofed any resource records for a
> child. A transcript of the NS records in the parents is a good start,
> although what is really needed is a transcript of everything that is seen
> for the child.
>

Is this because you're worried about the parent removing evidence of DNSSEC
for the child in the spoofing scenario?  If the parent tries to spoof with
DNSSEC for the child I would assume that seeing the DS SCT's in the log,
that is sufficient to find evidence of spoofing.  That said I think it
could be helpful to log NS as well for forensics.

One issue with logging all records seen is if webmail providers publish
SMIMEA there will be a potentially overwhelming number of records logged,
and a very large change rate.  Another issue is privacy of such records.


>
> In both cases, having transcripts from various DNS looking glasses around
> the Internet would give greater assurance of the integrity of the
> transcript.


I agree that would a good idea.

-Wei


>
> --Paul Hoffman
>