Re: [Ace] est-coaps clarification on /att and /crts

Jim Schaad <> Tue, 11 December 2018 17:50 UTC

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From: Jim Schaad <>
To: 'Michael Richardson' <>, <>, <>
CC: 'Peter van der Stok' <>, 'max pritikin' <>, "'Panos Kampanakis (pkampana)'" <>
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Date: Tue, 11 Dec 2018 09:50:00 -0800
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Subject: Re: [Ace] est-coaps clarification on /att and /crts
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Clarification requested - exactly what element is the Registrar?

The one item that I can generally think of that might be a problem is that
the answers to /att and /crts may differ based on the entity that is asking
the question.  In this case not having the entity being validated means that
the "wrong" answer may be returned or different answers would be returned
before and after validation.


> -----Original Message-----
> From: Ace <> On Behalf Of Michael Richardson
> Sent: Tuesday, December 11, 2018 8:29 AM
> To:;
> Cc: Peter van der Stok <>nl>; max pritikin
> <>om>; Panos Kampanakis (pkampana) <>
> Subject: [Ace] est-coaps clarification on /att and /crts
> A clarification question from an implementor (me) in the context of
> constrained BRSKI state machine.
> The /att and /crts requests do not do anything to change the state of
client or
> server.  It would seem that it might be safe to permit clients which have
not yet
> authenticated to do this operation.
> (/att gets CSR attributes, and /crts gets the list of trust anchors)
> When EST-COAPS is used on its own, there usually needs to be a
> trust anchor installed on the Registrar before any connection will be
> When EST-COAPS is used as step 2 of constrained-BRSKI, whether or not the
> Registrar will accept any (and all) connections depends upon configuration
> the operator.  Some devices might not be doing BRSKI (not need to, they
> already trust the operator, but they might still have IDevID only.  This
> happen during a transition)
> If the Registrar is "open" to new manufacturers, should the Registrar
> /att and /crts actions to be done by clients that it does not
> recognize?   The /att call on an ANIMA ACP network would reveal to the
> client the ULA that would be used for that client (and perhaps other
> things), and the /crts would show the name of the operator.
> Note that the later info probably is revealed just by doing the TLS
> I think that they should be restricted in general, but I'm concerned that
> might be some situation I've missed.
> --
> Michael Richardson <>ca>, Sandelman Software Works  -
> = IPv6 IoT consulting =-