[COSE] A couple of COSE questions

Laurence Lundblade <llundbla@qti.qualcomm.com> Thu, 15 June 2017 19:58 UTC

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From: Laurence Lundblade <llundbla@qti.qualcomm.com>
To: cose <cose@ietf.org>
Thread-Topic: A couple of COSE questions
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Date: Thu, 15 Jun 2017 19:58:08 +0000
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Subject: [COSE] A couple of COSE questions
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Hello I have a few questions…

Registration of hash algs
There’s no assignments for hash algs (SHA-256.. SHA-512, SHA3-256…) in the IANA registry here<https://www.iana.org/assignments/cose/cose.xhtml#algorithms>. I assume this is because the COSE protocol doesn’t have a need because they are bundled up with the signing alg identifiers.  For non-COSE protocols that use CBOR and do have a need to identify a hash, would it be reasonable to add them?  The COSE registry seems like it is the place to register algorithm IDs for use in CBOR in general.  I assume the process would be to write a simple RFC, publish and then add to the registry.


Registration of tagging for COSE messages
Why isn’t there a registry section for the tags for these different COSE messages?

   COSE_Tagged_Message = COSE_Sign_Tagged / COSE_Sign1_Tagged /
       COSE_Encrypt_Tagged / COSE_Encrypt0_Tagged /
       COSE_Mac_Tagged / COSE_Mac0_Tagged


Tagging of bstr wrapped data
It seems like it would be helpful to use an option tag on the bstr-wrapped payload for COSE_Sign and such to tell general purpose parsers and translators to remove the bstr wrapping and keep going. Tag 55799 seems like the best fit so far, but it may not be a perfect fit and it would be nice to use a tag less than 24.

Thanks!

LL