Subject: Re: Encapulated NXTs (was Opt-in wg last call)

From: Brian Wellington <[email-masked]>
Date: Wed, 10 Apr 2002 12:19:43 -0700 (PDT)

On 10 Apr 2002, Derek Atkins wrote:

> "Olaf M. Kolkman" <[email-masked]> writes:
> 
> > lambda and my are _not_ part of the NXT chain but the NXT chain is not
> > used for positive verification isn't it? In other words if lambda and mu
> > are signed by a key that is part of the chain of trust then they are
> > securely verified. The NXT can also be used for the denial of existence of
> > types. 
> 
> Of course it is used for positive verification.  It was created for
> that purpose (read: authenticated denial).  That's the point of the
> NXT chain.

NXTs were designed for authenticated denial, which is negative validation, 
not positive.  In this case, positive or negative refers to the type of 
response, not the result of the validation - that is, a positive 
validation would be over existing data, and a negative validation would be 
over nonexistant data.

Brian

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From: Derek Atkins <[email-masked]>
Date: 10 Apr 2002 16:24:50 -0400

> not positive.  In this case, positive or negative refers to the type of 

True, but you get positive verification of what RR types exist for a
particular name at the time the NXT was signed.  This is what I was
referring to.  You get authenticated denial of nodes between the NXTs
and you get authenticated existence of RRtypes at a node.

> validation would be over existing data, and a negative validation would be 

Correct.  The validation of RR data is via the SIG.  But if you have a
SIG that is outside the NXT chain then an attacker could just not send
it to you and you'd not know it was missing.

> Brian

-derek

-- 
       Derek Atkins, SB '93 MIT EE, SM '95 MIT Media Laboratory
       Member, MIT Student Information Processing Board  (SIPB)
       URL: http://web.mit.edu/warlord/    PP-ASEL-IA     N1NWH
       [email-masked]                        PGP key available

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From: Brian Wellington <[email-masked]>
Date: Wed, 10 Apr 2002 14:35:19 -0700 (PDT)

> and you get authenticated existence of RRtypes at a node.

While that is true, it's not really the intended use, and it wouldn't be 
used that way by any software.  Validation software would use the 
record+SIG as proof of existence, the NXT bit as proof of nonexistence, 
and anything else as proof of a problem.

I think we're violently agreeing here, though.

> it to you and you'd not know it was missing.

True.

Brian