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

Michael Richardson <> Wed, 12 December 2018 21:50 UTC

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From: Michael Richardson <>
To: Hannes Tschofenig <>
cc: "Panos Kampanakis \(pkampana\)" <>, "ace\" <>, "anima\" <>, Peter van der Stok <>, "Max Pritikin \(pritikin\)" <>
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Date: Wed, 12 Dec 2018 16:49:59 -0500
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Subject: Re: [Ace] [Anima] est-coaps clarification on /att and /crts
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Hannes Tschofenig <> wrote:
> > We want all our clients to be authenticated by DTLS before they start
> > loading up our RF network.
> > I'm not suggesting that the DTLS be skipped, I'm suggesting that the
> > client certificate presented might be meaningless to the EST server.

> I am curious what security model you have in mind? If you don't do client
> authentication then you are essentially issuing certificates to an
> anonymous entity. This feels like a very bad idea, particularly since the
> CA is supposed to assert the identifier of the client via the certificate.

Clients which are not **yet** authenticatable.
The client shows up, does a DTLS connection.

We let the DTLS connection succeed, because we want to record the particulars
of the client, so we can ask a human.  Much like happens when you ssh to
a new host: it stops to ask if you you agree with the key.
You don't know, so you hit ^C.
So, that's all.  We don't intend to issue certificates... yet.

I'm also asking if there is some use case where the client might legitimate
need the list of trust anchors (/cacerts request) in order so that it can...?
(I couldn't think of a use case)

Michael Richardson <>ca>, Sandelman Software Works
 -= IPv6 IoT consulting =-