Re: [Ace] ace-coap-est: unclear definition of /.well-known/est URI

[Esko Dijk <[e-mail]>]

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) <[e-mail]> 
Sent: Wednesday, September 12, 2018 17:31
To: Esko Dijk <[e-mail]>; [e-mail]
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:[e-mail]] On Behalf Of Esko Dijk
Sent: Wednesday, September 12, 2018 11:10 AM
To: mailto:[e-mail]
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