[COSE] early allocation for x5bag

[Michael Richardson <[e-mail]>]

Hi, in draft-ietf-anima-constrained-voucher, we are recommending use of x5bag
to contain the chain of certificates that this constrained version of BRSKI
(RFC8995) needs.  This is used in the request direction as per RFC8995
section 5.5.2, and in the return (RFC8366) voucher to provide any chain
that the pledge might need to validate the signature on the voucher.

We are planning to do interop at the hackathon, and implementors noticed that
we don't have a key value in draft-ietf-cose-x509.  This would be TBD4 in
Table 1.   Oops!

Can we ask the WG chairs to do an early allocation for these values?
(Or at least x5bag).  This is IANA Considerations section 4.1:

4.1.  COSE Header Parameter Registry

   IANA is requested to register the new COSE Header parameters in
   Table 1 in the "COSE Header Parameters" registry.  The "Value
   Registry" field is empty for all of the items.  For each item, the
   'Reference' field points to this document.

{i wish we would always put the URL of the Registry, because sometimes thing
are too similiarly named.  It is, I think:
https://www.iana.org/assignments/cose/cose.xhtml#header-parameters }

If we can't get a value allocated in time, I guess we could squat on the string 'x5bag' for now.
Code should plan to accept 'x5bag' and the new value until the end of the
summer, as we aren't sure if/when we'll get the allocation done.

I have written this into the interop planning document at:
  https://docs.google.com/document/d/1T8Rtfk1zia_p05_6eb_WQA2Mmid-eP1-cAgnwdpF9Xk/edit?usp=sharing

--
Michael Richardson <[e-mail]>   . o O ( IPv6 IøT consulting )
           Sandelman Software Works Inc, Ottawa and Worldwide