Re: [Rats] [Cbor] πŸ”” WGLC on draft-ietf-cbor-tags-oid-02

Carsten Bormann <cabo@tzi.org> Thu, 29 October 2020 20:25 UTC

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From: Carsten Bormann <cabo@tzi.org>
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Date: Thu, 29 Oct 2020 21:25:45 +0100
Cc: Francesca Palombini <francesca.palombini=40ericsson.com@dmarc.ietf.org>, "sacm@ietf.org" <sacm@ietf.org>, "rats@ietf.org" <rats@ietf.org>, "draft-ietf-cbor-tags-oid@ietf.org" <draft-ietf-cbor-tags-oid@ietf.org>
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To: Laurence Lundblade <lgl@island-resort.com>
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Subject: Re: [Rats] =?utf-8?q?=5BCbor=5D_=F0=9F=94=94_WGLC_on_draft-ietf-cbor?= =?utf-8?q?-tags-oid-02?=
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Hi Laurence,

On 2020-10-29, at 20:44, Laurence Lundblade <lgl@island-resort.com> wrote:
> 
> The question I have is whether there is any intent for these OIDs to be keys or labels in CBOR maps.

The way tag factoring (Section 5 [1]) works for maps was specifically meant to support this.

> In X.509/PKIX extensions are labeled by OIDs. Would there be similar use in CBOR?

Please see the example on page 8 [2] for such usage.

> Typically, CBOR map labels are integers and sometimes text strings. Having to pay attention to tags in map keys might be very inconvenient for some CBOR decoders, though that could be avoided in a given protocol by saying the map keys are byte strings that borrow tag 111 content eliminating the need for the tag.

That is of course also possible.

Which reminds me that we specify CDDL control operators, but not prelude-like conventional names for the types created by these tags (e.g., cf. [3]).  Now Issue 6 [4].

Grüße, Carsten

[1]: https://www.ietf.org/archive/id/draft-ietf-cbor-tags-oid-02.html#name-tag-factoring-with-oid-arra
[2]: https://tools.ietf.org/html/draft-ietf-cbor-tags-oid-02#page-8
[Yessss… :-)]
[3]: https://www.rfc-editor.org/rfc/rfc8746.html#section-5
[4]: https://github.com/cbor-wg/cbor-oid/issues/6