Re: [COSE] tstr values for kty, alg, crv, etc.

Yes, I much prefer int labels for a small C implementation. Adding support for tstr labels would noticeably increase code size. I hope no one registers a tstr label.  It seems unlikely because algorithms are relatively hard to invent and vet.

LL

> On Jul 28, 2021, at 5:47 AM, Carsten Bormann <cabo@tzi.org> wrote:
> 
> Hi Daisuke,
> 
>> On 2021-07-28, at 13:45, AJITOMI Daisuke <ajitomi@gmail.com <mailto:ajitomi@gmail.com>> wrote:
>> 
>> In my opinion, the tstr type for 'kty', 'alg', 'crv' or 'key_ops' is not necessary because I think the major advantage of COSE is its compactness,but I would like to know what you are assuming as the value of tstr.
> 
> The registrant gets the choice between a text string and an integer.
> 
> https://www.iana.org/assignments/cose/cose.xhtml <https://www.iana.org/assignments/cose/cose.xhtml> lists the registration procedures for certain ranges, e.g.:
> 
> https://www.iana.org/assignments/cose/cose.xhtml#algorithms <https://www.iana.org/assignments/cose/cose.xhtml#algorithms>
> 
> Range <sort_none.gif>	Registration Procedures <sort_up.gif>
> Strings of length 1	Standards Action With Expert Review
> Integer values between -256 and 255	Standards Action With Expert Review
> Strings of length 2	Specification Required
> Integer values from 256 to 65535	Specification Required
> Integer values from -65536 to -257	Specification Required
> Strings of length greater than 2	Expert Review
> Integer values greater than 65535	Expert Review
> 
> So labels the representations of which would be 1+0 and 1+1 bytes long require standards action, 1+2, specification required, and 1+>2, expert review.
> 
> It doesn’t look like anyone has felt a need to register a text string label for an algorithm ID yet; there are still quite a few 1+1 (and even a few 1+0!) values available for registration.
> 
> I would expect that, until we run out of codepoints, the registration of text labels will remain an occurrence for special circumstances (which means we might not be prepared for text labels when we finally actually need them).
> 
> Grüße, Carsten
> 
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