Re: Summary of IETF LC for draft-ietf-dane-openpgpkey

Hi,


On 9/16/15 12:14 PM, Philip Homburg wrote:
> In your letter dated Tue, 15 Sep 2015 21:11:05 -0400 you wrote:
> > In addition, as Christian more or less pointed out, if the IETF
> > is really making a very strong commitment to privacy, creating
> > an easily-harvestable source of verified email addresses doesn't
> > seem to be a good idea.  Perhaps the tradeoffs justify it, but
> > the document would be a lot better if that particular analysis
> > and set of considerations were explained.
> I'm curious about the attack scenario here.
>
> Assuming the DNS zone is properly protected using NSEC3, performing a 
> dictionary attack would mean either one DNS request per try or one NSEC3 hash.
> I'm assuming here that NSEC3 can be made at least as expensive as any
> proposed hashing scheme for the LHS of the e-mail address.
When this is true you may be right.  And I state this as someone who has
deployed DNSSEC.  Most haven't.  That's a pity.

> One DNS request is about as expensive as trying a RCPT TO on the mail server
> itself.
Perhaps but you seem to think it's an either/or thing.  It seems likely
that once they're there, someone's going to try to get at them.  We
simply can't expect otherwise.

Eliot

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