It's been a while, but I've updated the Composite Claims document based on
much of the feedback I've received from this group. I went ahead and
renamed it to include the group name so it's easier for folks to notice
that it's here.

https://datatracker.ietf.org/doc/draft-lemmons-cose-composite-claims/00/

The new draft has CDDL to more clearly communicate the formats as well as
significantly expanded examples demonstrating how they can be used.

On Fri, Oct 27, 2023 at 3:21 AM Chris Lemmons <[email protected]> wrote:

> Yup! Those are both relevant and useful, though they don't support exactly
> the same use cases.
>
> In particular, SD-CWTs don't quite work for the bearer tokens I'd like to
> use because I'd like the _issuer_ to deny access to the non-disclosed claim
> _values_. The bearer needs to not have to modify their token. Additionally,
> I need the relying party to be able to read the claim key so they can tell
> if the stuff inside the envelope might be a problem. A relying party that
> doesn't care what the identity of the bearer is might accept a token that
> has an envelope with an identity claim inside. A relying party that does
> care might reject the request if they can't open the envelope to verify the
> identity.
>
> I hadn't seen the JPTs before, but the Design Considerations section does
> a good job of highlighting where these approaches differ. For
> example, conveying claim values from issuer to relier without revealing
> them to the bearer is one of the goals of this envelope and that should be
> called out because it has both security and privacy implications.
>
> On Thu, Oct 26, 2023 at 3:27 PM Orie Steele <[email protected]>
> wrote:
>
>> Hey Chris!
>>
>> Glad to see the draft : )
>>
>> I am very interested in this, and look forward to hearing from others,
>> regarding the approach in the draft.
>>
>> Because this draft comments on both signatures and encryptions in
>> relation to CWT claims I wanted to share 2 other related threads for folks
>> who are interested in the general properties of disclosure and linkability:
>>
>> 1. https://datatracker.ietf.org/doc/draft-prorock-cose-sd-cwt/ (like
>> https://datatracker.ietf.org/doc/draft-ietf-oauth-selective-disclosure-jwt/
>> but for CWT).
>> 2.
>> https://datatracker.ietf.org/doc/html/draft-ietf-jose-json-proof-token-02 (
>> has selective disclosure and unlinkability capabilities, which you might be
>> interested in leveraging, alongside or instead the logical operators)
>>
>> Regards,
>>
>> OS
>>
>> On Thu, Oct 26, 2023 at 4:00 PM Chris Lemmons <[email protected]> wrote:
>>
>>> Link up front:
>>> https://datatracker.ietf.org/doc/draft-lemmons-composite-claims/
>>>
>>> This is new work I'd like to see if there is interest in. I have a
>>> specific need for these particular CWT claims, but they're completely
>>> general and not specific to my use-case. I have a draft linked above,
>>> but the core concept is that sometimes, you need to compose claims
>>> with boolean logic or encrypt the claim contents.
>>>
>>> For example:
>>>
>>> I am Chris or David, but I decline to tell you which. If that's ok
>>> with you, you can accept my credential.
>>>
>>> Or to encrypt a claim, consider:
>>>
>>> I have a bearer token with a claim about who I am, but it is
>>> encrypted, and a claim for what I am authorized to access, which is in
>>> the clear. A processor that only cares about the latter doesn't need a
>>> decryption key for the former, allowing the token to be processed by
>>> an entity without revealing the identity to the processor.
>>>
>>> And lastly, it defines a crit claim for cwts, which doesn't exist yet.
>>>
>>> I think this document should be very simple and direct in scope. It
>>> shouldn't need to go into detail about all the possible way these
>>> elements can be composed. It just needs to register the compositions
>>> and explain how they can be safely used and how they must be
>>> processed.
>>>
>>> What are your thoughts? Would it be worth a few minutes of agenda at
>>> 118 to explain and answer questions, if we have time available?
>>>
>>> _______________________________________________
>>> COSE mailing list
>>> [email protected]
>>> https://www.ietf.org/mailman/listinfo/cose
>>>
>>
>>
>> --
>>
>>
>> ORIE STEELE
>> Chief Technology Officer
>> www.transmute.industries
>>
>> <https://transmute.industries>
>>
>
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