Re: [Cbor] draft-ietf-cbor-cddl-control-00 should add CDDL notation for CBOR Sequences

Hi Henk,

To quote RFC 8764

1) "CBOR Sequences are already supported as contents of byte strings using the ".cborseq" control operator"
2) "CDDL does not provide for unadorned CBOR Sequences as a top-level subject of a specification"

All the document I cited do 2) not 1) .cborseq as currently specified is not a solution.

Cheers,
John

-----Original Message-----
From: Henk Birkholz <henk.birkholz@sit.fraunhofer.de>
Date: Thursday, 5 November 2020 at 15:29
To: John Mattsson <john.mattsson@ericsson.com>, "cbor@ietf.org" <cbor@ietf.org>
Subject: Re: [Cbor] draft-ietf-cbor-cddl-control-00 should add CDDL notation for CBOR Sequences

Hi John,

as the control for cborseq is introduced in:

> https://tools.ietf.org/html/rfc8610#section-3.8.4

and RFC8742 states that:

>    Currently, CDDL does not provide for unadorned CBOR Sequences as a
>    top-level subject of a specification.  For now, the suggestion is to
>    use an array for the top-level rule, as is used for the ".cborseq"
>    control operator, and add English text that explains that the
>    specification is really about a CBOR Sequence with the elements of
>    the array

it seems to me that you are asking for a specific CDDL notation that can 
represent a cborseq as a top-level subject. Why is using an array here 
not good enough in your case?

Viele Grüße,

Henk

On 05.11.20 13:49, John Mattsson wrote:
> Hi,
> 
> I the most important missing piece in RFC 8610 is the lack of CDDL for CBOR Sequences (RFC 8742) and I think draft-ietf-cbor-cddl-control would be a good place to add CDDL for that.
> 
> CBOR sequences has already been standardized in RFC 8742. CBOR sequences are used quite heavily in IETF documents such as RFC 8769, draft-ietf-6tisch-minimal-security, draft-ietf-lake-edhoc, draft-palombini-core-oscore-edhoc, draft-mattsson-cose-cbor-cert-compress, etc.
> 
> I don't understand all the complexities of CDDL formalism, but this seems like a quite easy thing to solve. I do not care exactly which notation is used, but could we please just agree on something and put in a draft.
> 
> The notation could be something like:
> 
> - reuse the CDDL notation for group ( ... )
> - reuse the Diagnostic Notation for CBOR sequences << ... >>
> - Some modification of the CDDL array notation ] ... [
> - Something looking like symbol swearing #$%@#$% ... #$%@#$%
> ...
> 
> Cheers,
> John
> 
> 
> 
> 
> 
> 
> 
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