[Rats] Robert Wilton's Discuss on draft-ietf-rats-eat-21: (with DISCUSS and COMMENT)

[Robert Wilton via Datatracker <[e-mail]>]

Robert Wilton has entered the following ballot position for
draft-ietf-rats-eat-21: Discuss

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DISCUSS:
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Hi,

Thanks for this document.  Sorry, I didn't have time to review this document
that closely.  I have flagged one issue for discussion to change the reference
to the architecture document to being a normative reference.  This would mean a
downref, but should otherwise be an easy change to make.  The rest of my
comments are non-blocking.

(1) p 71, sec 11.2.  Informative References

   [RATS.Architecture]
              Birkholz, H., Thaler, D., Richardson, M., Smith, N., and
              W. Pan, "Remote ATtestation procedureS (RATS)
              Architecture", Work in Progress, Internet-Draft, draft-
              ietf-rats-architecture-22, 28 September 2022,
              <https://datatracker.ietf.org/doc/html/draft-ietf-rats-
              architecture-22>.

"From section 1.3, EAT follows the operational model described in Figure 1 in
[RATS.Architecture].".  This, along with other references indicates that the
RATS architecture should be a normative reference.


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COMMENT:
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(2) p 0, sec

   An EAT is either a CBOR Web Token (CWT) or JSON Web Token (JWT) with
   attestation-oriented claims.

This is probably contentious, but given that this is a new spec, I wonder
whether it wouldn't be better (i.e., encourage wider interop) if only CBOR,
COSE and CWT were used/allowed.

(3) p 20, sec 4.2.6.  swname (Software Name) Claim

   The "swname" claim contains a very simple free-form text value for
   naming the software used by the entity.  Intentionally, no general
   rules or structure are set.  This will make it unsuitable for use
   cases that wish precise naming.

I found it interesting, and slightly surprising, that the hardware model claim
is opaque, but the software name claim is not.

(4) p 24, sec 4.2.11.  uptime (Uptime) Claim

   The "uptime" claim MUST contain a value that represents the number of
   seconds that have elapsed since the entity or submodule was last
   booted.

Relative to other claim descriptions, the MUST in this description seems
strange.  Perhaps better as just "The "uptime" claim contains a value ..."

(5) p 88, sec Appendix B.  UEID Design Rationale

   A UEID is not a UUID [RFC4122] by conscious choice for the following
   reasons.

Note that the UUID spec is currently being updated (it is also on this week's
telechat review), so some of the concerns being described here may no longer be
valid.  It is still only 128 bits though, and 6 bits are spent identifying UUID
format and version.

(6) p 89, sec Appendix B.  UEID Design Rationale

   Note also that that a type 2 UEID (EUI/MAC) is only 7 bytes compared
   to 16 for a UUID.

Note that the paragraph at the end of appendix B.1. states that UEIDs are a
minumum of 128 bits ...

Regards,
Rob