[Cbor] Robert Wilton's Discuss on draft-ietf-cbor-tags-oid-06: (with DISCUSS and COMMENT)
Robert Wilton via Datatracker <noreply@ietf.org> Thu, 08 April 2021 12:06 UTC
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Date: Thu, 08 Apr 2021 05:06:08 -0700
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Subject: [Cbor] Robert Wilton's Discuss on draft-ietf-cbor-tags-oid-06: (with DISCUSS and COMMENT)
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Robert Wilton has entered the following ballot position for draft-ietf-cbor-tags-oid-06: Discuss When responding, please keep the subject line intact and reply to all email addresses included in the To and CC lines. (Feel free to cut this introductory paragraph, however.) Please refer to https://www.ietf.org/iesg/statement/discuss-criteria.html for more information about IESG DISCUSS and COMMENT positions. The document, along with other ballot positions, can be found here: https://datatracker.ietf.org/doc/draft-ietf-cbor-tags-oid/ ---------------------------------------------------------------------- DISCUSS: ---------------------------------------------------------------------- Hi, Hopefully not tricky to discuss/resolve, sorry for posting it close to the telechat! I would like to please see some more clarity or guidance about when TAG TBD112 should be used, given that there are two possible encodings of absolute OIDs below "1.3.6.1.4.1". Specifically, the questions that I have, that probably need to be clarified are: - is a CBOR encoder allowed to optimize a TBD110 tag into a TBD112 tag? - Should CBOR decoder clients always expect to be able to handle both TBD110 and TBD112 tags? - Or, it the decision over whether to use TBD110 or TBD112 down to the application and the application needs to agree which is use. ---------------------------------------------------------------------- COMMENT: ---------------------------------------------------------------------- I found this document to be interesting because I knew from the title that it was going to only be 4 pages long and say that OIDs are obviously encoded as a tagged array, hence I was surprised to see that was not the solution and it uses BER encoded OIDs instead. The document explains, and I think that I understand why this has been done, but I question whether the title of the document and name of the tags is right. Is it really a CBOR representation of OIDs, or is it actually a CBOR representation of BER encoded OIDs? I.e., it is plausible that there would ever be a requirement for non BER encoded OIDs. E.g., I'm not an ASN.1 expert, but say if somewhat wanted to do a CBOR encoding of ASN.1, then it is not obvious to me that they would use a BER encoding for OIDs. Hence the suggestion is to make the title, abstract, and name of the tags clear that it is about the CBOR encoding or BER encoded OIDs. In the introduction: Since the semantics of absolute and relative object identifiers differ, this specification defines two tags, collectively called the "OID tags" here: I presume that this should be three tags? In section 4.1. Tag Factoring Example: X.500 Distinguished Name: The diagram uses a mix of single letters (e.g. c for country), and a full name "street". Is this how the X.500 attributes are defined? Otherwise it might be clearer to always use their full names. The country and street RDNs are single-valued. The second and fourth RDNs are multi-valued. Perhaps: "The country (first) and street (third) RDNs are single-valued. The second and fourth RDNs are multi-valued." h'550407': "Los Angeles", h'550408': "CA", I think that the example would be more clear by splitting the city and county onto separate lines. Finally, the document contains these two sentences that seem to somewhat conflict with each other: "While these sequences can easily be represented in CBOR arrays of unsigned integers, a more compact representation can often be achieved by adopting the widely used representation of object identifiers defined in BER; this representation may also be more amenable to processing by other software that makes use of object identifiers." compared to: "Staying close to the way object identifiers are encoded in ASN.1 BER makes back-and-forth translation easy; otherwise we would choose a more efficient encoding." Regards, Rob
- [Cbor] Robert Wilton's Discuss on draft-ietf-cbor… Robert Wilton via Datatracker
- [Cbor] OID representation (was: Re: Robert Wilton… Carsten Bormann
- Re: [Cbor] OID representation (was: Re: Robert Wi… Francesca Palombini
- Re: [Cbor] OID representation (was: Re: Robert Wi… Carsten Bormann
- Re: [Cbor] Robert Wilton's Discuss on draft-ietf-… Carsten Bormann