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Re: [certid] What security does SRV-ID add when DNS-ID will always match?

Matt McCutchen <matt@mattmccutchen.net> Wed, 30 March 2011 21:58 UTC

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From: Matt McCutchen <matt@mattmccutchen.net>
To: Peter Saint-Andre <stpeter@stpeter.im>
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Date: Wed, 30 Mar 2011 18:00:12 -0400
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Cc: IETF cert-based identity <certid@ietf.org>, =JeffH <Jeff.Hodges@KingsMountain.com>
Subject: Re: [certid] What security does SRV-ID add when DNS-ID will always match?
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On Wed, 2011-03-30 at 23:51 +0200, Peter Saint-Andre wrote:
> On 3/30/11 11:45 PM, Matt McCutchen wrote:
> > On Wed, 2011-03-30 at 23:00 +0200, Peter Saint-Andre wrote:
> >> I think that this is a matter of local policy -- a client could prefer
> >> SRV-IDs yet still accept DNS-IDs, and as far as I can see that behavior
> >> is not expressly forbidden by the spec.
> > 
> > "Prefer" is vague.  Specifically, I would like the client to accept a
> > DNS-ID if and only if the certificate contains no SRV-IDs.  How is this
> > accommodated within the framework of the spec?  Clearly the reference
> > identifier must contain a DNS-ID. 
> 
> Ah, I see the confusion. MUST has been changed to SHOULD in order to be
> consistent with what I have called the inclusion approach.

I'm not referring to the change in the document.  I meant that the goal
of accepting a DNS-ID in the case that the certificate contains no
SRV-IDs is impossible to achieve unless the (fixed) list of reference
identifiers contains a DNS-ID.  With that clarification, consider my
message.

-- 
Matt

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