Subject: [Rats] Review of draft-birkholz-rats-uccs-01

From: Russ Housley <[email-masked]>
Date: Thu, 30 Jul 2020 16:45:40 -0400

# Major Concerns

In Section 3.1, the re are two MUST requirements, but they are not presented clearly.  The are:

   1)  The secure channel MUST authenticate the Verifier to the Attester.

   2)  The secure channel MUST protect the integrity of the communications from the Verifier to the Attester.

The way it is written also requires integrity protection in both directions.  Is that really needed?

In Section 3.1, says:

   Further, the provider of the UCCS SHOULD be
   authenticated by the reciever to ensure the channel is truly secured
   and the sender is validated.

I do not understand what this is trying to say beyond the MUST requirement above.  Maybe part of the problem is the mixing of the discussion about authentication and integrity.

In Section 3, when talking about confidentiality, I think that it would be better to say:

      If confidentiality is also required, the secure channel SHOULD mutually authenticate Verifier and the Attester.

# Minor concerns

In section 1, the phrase "Secure Channel provides the correct properties" is a bit troublesome.  The properties are not difficult to explain in a sentence or two, so they should just be stated here.  Also, the sentences that follow can be omitted if you simply include in the summary of the "correct properties" that the party sending the UCCS is authenticated.

In Section 1.1, please add Verifier and Attester the the terms that are defined.

# Nits

General: Why are Claim and Secure Chanel capitalized?

In section 1.1, please add a reference for the CWT Claims Registry.

In section 2, please add a reference for a device's trusted execution environment (probably the TEEP architecture draft).

Russ