I don’t think tstr can be removed from the standard. That would break backwards 
compatibility. Maybe a strong recommendation could be added with the comment 
that many implementations don’t support tstr.

There is a revision of 8152 in process right now called 8152bis. That seems 
like the place to do it.

LL


> On Aug 5, 2021, at 8:29 PM, AJITOMI Daisuke <[email protected]> wrote:
> 
> Hi folks,
> 
> > I prefer to see the option of `tstr` labels removed if possible.
> 
> I'm glad to see that there are several people who agree with me.
> 
> To remove the option of tstr labels from the spec, would a revised RFC be 
> needed? Or would an errata enough for that?
> Anyway, I would like to hear from the key members in COSE whether this change 
> is acceptable or not.
> 
> If it is acceptable, I would like to support moving this effort forward.
> 
> Best regards,
> Daisuke
> 
> 2021年8月5日(木) 19:48 Jeremy O'Donoghue <[email protected] 
> <mailto:[email protected]>>:
> Hi list,
> 
>  
> 
> I agree with Laurence on this. I work on platform-related security standards 
> at GlobalPlatform where we are using COSE quite extensively. A major use-case 
> is highly constrained embedded targets where the benefits from eliminating 
> string handling are considerable – many such platforms do not have a heap, 
> and minimal code size is an important design goal.
> 
>  
> 
> I prefer to see the option of `tstr` labels removed if possible. We do have a 
> 64bit integer space for algorithms which should suffice. If this is not 
> possible (e.g. for backward compatibility with proprietary implementations), 
> at least a note to registrants that integer values are greatly preferred in 
> some implementations for reasons of code size would be helpful. 
> Implementations could then decide whether to not implement tstr support.
> 
>  
> 
> Best regards
> 
> Jeremy
> 
> 
> 2021年7月29日(木) 5:50 Laurence Lundblade <[email protected] 
> <mailto:[email protected]>>:
> 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 <[email protected] 
>> <mailto:[email protected]>> wrote:
>> 
>> Hi Daisuke,
>> 
>>> On 2021-07-28, at 13:45, AJITOMI Daisuke <[email protected] 
>>> <mailto:[email protected]>> 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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> 

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