Hi Esko,
Good point. We made this change to ensure the text is clearer. You will see it 
in the next iteration.
Thank you, 
Panos

-----Original Message-----
From: Esko Dijk [mailto:esko.d...@iotconsultancy.nl] 
Sent: Saturday, September 15, 2018 10:30 AM
To: Panos Kampanakis (pkampana) <pkamp...@cisco.com>; ace@ietf.org
Subject: RE: ace-coap-est: unclear definition of /.well-known/est URI

Hello Panos,

Thanks - it's clear now that the "ArbitraryLabel" needs to be supported for 
this use case. The unclarity in the current text comes from the fact that the 
default /.well-known/est/<short-est> is missing ; which should be supported 
also as in RFC 7030. Also the usage of the discoverable root URI is missing 
here.

So we could update the text in Section 5 as follows:

------
The individual EST-coaps well-known server URIs differ from the EST URI by 
replacing the scheme https by coaps and by specifying shorter resource path 
names:

   coaps://www.example.com/.well-known/est/<short-est>
   coaps://www.example.com/.well-known/est/ArbitraryLabel/<short-est>

The ArbitraryLabel Path-Segment, if used, SHOULD be of the shortest length 
possible.

The optional additional EST-coaps server URIs, obtained through discovery of 
the EST root resource(s), are of the form:

   coaps://www.example.com/<est-root-resource>/<short-est>
   coaps://www.example.com/<est-root-resource>/ArbitraryLabel/<short-est>

------

The suggestion by Peter to add references to the corresponding EST RFC 7030 
sections is also good.

Regards
Esko

From: Panos Kampanakis (pkampana) <pkamp...@cisco.com>
Sent: Wednesday, September 12, 2018 17:31
To: Esko Dijk <esko.d...@iotconsultancy.nl>; ace@ietf.org
Subject: RE: ace-coap-est: unclear definition of /.well-known/est URI

Hi Esko,

Thanks for the comment. 

Certificate authorities use the ArbitraryLabel in order to direct the CSR 
request and issue certificates based on a certain policy / cert profile. For 
example, if you are ClientX you get label ClientX198282 and when you hit the CA 
HTTP URI .well-known/est/ ClientX198282/sen the CA knows to use the policy for 
ClientX in order to issue a certificate. Of course, someone that has deployed 
an on-prem CA that has the same cert profile for all endpoints will not need an 
arbitrary label and the default EST namespace is enough.  

So, even though coaps://www.example..com/.well-known/est/<short-est> would work 
for many cases, we needed to keep the 
coaps://www.example..com/.well-known/est/ArbitraryLabel/<short-est> as well for 
cases where the client is getting a cert from a CA that serves more than on 
cert profiles. We may need to specify that the labl should be as short as 
possible, even though it is kind of self-explanatory. 

I hope it makes sense.

Panos


From: Ace [mailto:ace-boun...@ietf.org] On Behalf Of Esko Dijk
Sent: Wednesday, September 12, 2018 11:10 AM
To: mailto:ace@ietf.org
Subject: [Ace] ace-coap-est: unclear definition of /.well-known/est URI

Dear all/authors of ace-coap-est,

Section 5 of ace-coap-est-05 indicates URI discovery is possible to find the 
EST functions entry point URI. Also a well-known URI is defined:

coaps://www.example..com/.well-known/est/ArbitraryLabel/<short-est>.

This URI seems more complicated than needed? What if we simply define an 
always-available well-known URI, usable without any discovery:

coaps://www.example..com/.well-known/est/<short-est>

This re-uses the well-known EST namespace which is exactly defined to do EST 
functions. So using the short-est names within this namespace should be fine.
It is important that a well-known URI is available that is usable without 
discovery, just like EST RFC 7030 defines it for https.
The "ArbitraryLabel" only makes the URI longer.

best regards
Esko Dijk

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