Re: [DNSOP] Comments regarding the NSEC5

[Jan Včelák <[e-mail]>]

On Thursday, March 12, 2015 11:31:37 AM Florian Weimer wrote:
> On 03/12/2015 11:15 AM, Jan Včelák wrote:
> > On Wednesday, March 11, 2015 09:52:55 AM Nicholas Weaver wrote:
> >> Why not just do something simpler?  The only thing NSEC5 really differs
> >> in a way that counts is not in the NSEC record but really just the
> >> DNSKEY handling, having a separate key used for signing the NSEC*
> >> records.
> >> 
> >> So why define NSEC5 at all.
> >> 
> >> Instead, just specify a separate flag for the DNSKEY record, "NSEC-only",
> >> sign the NSEC3 dynamically, bada bing, bada boom, done!
> > 
> > This would not work. Anyone holding the NSEC-only private key could fake
> > denying answers for the zone. So if your zone is slaved by a less-trusted
> > party, they could still manipulate your zone. This is not possible with
> > NSEC5.
> They can still respond with SERVFAIL instead of supplying a signed
> answer, achieving roughly the same result.
> 
> A better argument would be support for opt out, where signatures from
> the online key could introduce unauthorized positive answers.  It's
> still not a very strong argument, admittedly.  The DNS software itself
> is likely signed by a key which is kept online (more or less).  Online
> keys are less threatening than they used to be, and we aren't even
> talking about long-term keys baked into software, but short/medium-term
> keys which are easily replaced.
> 
> And does anyone actually use opt out with NSEC3?

Yes, .com for example. My impression was that Opt-Out was the selling point of 
NSEC3, not the domain name hashing.