Re: [Rats] I-D: draft-rundgren-cote-00

Anders Rundgren <anders.rundgren.net@gmail.com> Thu, 21 July 2022 08:11 UTC

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To: Thomas Fossati <tho.ietf@gmail.com>, Laurence Lundblade <lgl@island-resort.com>, henk Birkholz <henk.birkholz@sit.fraunhofer.de>
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From: Anders Rundgren <anders.rundgren.net@gmail.com>
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Subject: Re: [Rats] I-D: draft-rundgren-cote-00
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On 2022-07-21 8:56, Thomas Fossati wrote:
> Hi Anders,

Hi Thomas,
comments in line.

> 
> On Thu, Jul 21, 2022 at 6:09 AM Anders Rundgren
> <anders.rundgren.net@gmail.com> wrote:
>>
>> On 2022-07-20 21:32, Michael Richardson wrote:
>>>
>>>> The primary purpose is to enable developers defining community- or
>>>> application-specific type identifiers without having to go through an IANA
>>>> registration process. Although the scheme imposes no restrictions on type
>>>> identifiers (beyond being valid CBOR data items), using URLs should due to
>>>> their ubiquity be a candidate for CBOR based standards.
>>>
>>> I'm not sure I understand why RATS is on the CC.
>>
>> Well, the RATS WG is just about to adopt an entirely different CBOR object typing scheme :)
> 
>  From a quick glance, there seems to be substantial difference in scope
> between the two: one proposes a bunch of media types for EAT, the
> other an alternative typing system for CBOR.

As we all know there are almost always alternatives to achieving a specific goal.
Alternatives typically also come with different pros and cons.  FWIW, I try to evaluate the pros and cons of different approaches although the "weight" of each feature remains a thorny issue because it tends to be pretty subjective :)

In this case my assumption is that the overarching goal is providing an object typing mechanism permitting a common receiver dispatching the handling of received objects to different processors depending on their type.

This is something I have worked with since 20Y+ back based on object-integral typing-schemes like XML Schema, and more recently with JSON.  Adding such a feature to CBOR was a no-brainer.

In RATS it appears that you are currently dealing with not less than three different typing systems (media types, CBOR tags, profile URLs) which (in my simple mind...) feels slightly over the top.

I wouldn't completely ignore the fact that FIDO adopted the object-integral typing concept for attestations:
https://github.com/cyberphone/fwp/blob/main/testdata/fido2testvectors.json

Cheers,
Anders

> 
> Echoing Michael, I am not sure this is directly in scope for RATS.
> 
> And with regards to its applicability to EAT, it seems to lack a bit
> of generality as it only addresses the CBOR side of the EAT coin.
> 
> cheers, thanks