Re: [Rats] Early feedback for draft-tschofenig-rats-aiss-token

["Smith, Ned" <[e-mail]>]

I read parts of it differently as the focus of the claims is on the RoT which in one instance (section 3.3) described as a RoT that can be 'immutable' and goes on to say that RoT details are from a manufacturer. I interpret this to mean the aiss claims are Endorsements provided by Endorsers. 

-Ned

On 4/29/22, 12:38 AM, "RATS on behalf of Henk Birkholz" <[e-mail] on behalf of [e-mail]> wrote:

    Hi authors,

    considering this is a -00 it was a quick an comprehensive read. I am 
    aware that in this state the document is basically a list of Claim 
    definitions and corresponding CDDL.

    A few questions and comments:

    1.) It seems that an AISS is Evidence as it is consumed by a Verifier 
    and reference values and policies are used to appraise it:

    > https://www.ietf.org/archive/id/draft-tschofenig-rats-aiss-token-00.html#section-7

    As "Verification" is a bit of an ambiguous term nowadays, I'd recommend 
    to rename Section 7 to "AISS Token Appraisal". Also, I would clearly 
    state that an AISS token is Evidence early on.

    2.) The colloquial term "verification service" is used in:

    > https://www.ietf.org/archive/id/draft-tschofenig-rats-aiss-token-00.html#section-3.3

    which currently only implies that that is a Verifier conducting AISS 
    token Evidence appraisal, I think. Just defining what a verification 
    service is (see 1.) would help as there are other colloquial terms that 
    mean the same thing, such as attestation service (which also are ambiguous).

    3.) Are the reports mentioned in:

    > https://www.ietf.org/archive/id/draft-tschofenig-rats-aiss-token-00.html#section-3.4

    self-assertions or Evidence or something else? Are they produced by a 
    RoT or a higher Attesting Environment? Are these states Claims that can 
    be collected from Target Environments that are "the silicon" or are they 
    derived in a different manner?

    4.) I am wondering which Attesting Environment is supposed to produce 
    the AISS token Evidence. In your definition of a RoT (Which I'll come to 
    in the next item) it is highlighted that a boot loader can be a RoT, 
    which would imply in that example that the bootloader is the first 
    Attesting Environment in layered attestation.

    Is the first Attesting Environment always the producer of an AISS token 
    or can later Attesting Environment also do that? I am asking because, if 
    you look at the scenario from a certain angle, it seems as if the 
    Attestation Environment (bootloader) would collect claims from Target 
    Environments that would be the parts of the Silicon. Is that correct?

    5.) What's the intended output of an AISS token appraisal? Theft and 
    Overouse seem to be two characteristics as stated in:

    > https://www.ietf.org/archive/id/draft-tschofenig-rats-aiss-token-00.html#section-3.6

    Are there others? I assume that determining certain Attestation Results 
    is the whole point of producing AISS tokens in the first place. Defining 
    those categories of outcomes seem to be in-scope?

    6.) In March Kathleen advised the RATS WG to include an explicit 
    definition of Root of Trust in the RATS architecture. AFAIK, that is 
    that only remaining open issue with the document. Maybe we can 
    collaborate on that definition as you started one here and I don't think 
    it's an awful definition? :o) That would be cool and hopefully move the 
    RATS architecture, which seems to be stuck for quite a while now and 
    that issue might have been the reason.

    7.) I like how most of your Claims used/defined are matching the layout 
    of CoRIM :-) (obviously) and thanks for naming it AISS and not AISST and 
    therefore avoid calling them AISST tokens later :-)

    Viele Grüße,

    Henk

    _______________________________________________
    RATS mailing list
    [e-mail]
    https://www.ietf.org/mailman/listinfo/rats