[OAUTH-WG] Re: We cannot trust Issuers

[Watson Ladd <[e-mail]>]

I've opened https://github.com/oauth-wg/oauth-selective-disclosure-jwt/pull/448
as a step torwads this.

On Wed, Jul 31, 2024 at 5:31 AM Brian Campbell
<[e-mail]> wrote:
>
>
>
> On Tue, Jul 23, 2024 at 11:15 AM Leif Johansson <[e-mail]> wrote:
>>
>> On Mon, 2024-07-22 at 19:43 -0400, Richard Barnes wrote:
>> > I would observe that any solution based on garden-variety digital
>> > signature (not something zero-knowledge like BBS / JWP) will have
>> > problems with issuer/verifier collusion.  One-time tokens and batch
>> > issuance don't help.  There is no such thing as SD-JWT with
>> > issuer/verifier collusion resistance.  At best you could have SD-JWP.
>> >
>> > I don't think this needs to be a blocker on SD-JWT.  There are use
>> > cases that don't require issuer/verifier collusion resistance.  We
>> > should be clear on the security considerations and warn people away
>> > who care about issuer/verifier collusion resistance, and accelerate
>> > work on SD-JWP if that's an important property to folks.
>> >
>>
>>
>> +1 on this
>
>
> I'm generally a +1 on this too.  There is an attempt at a discussion around unlinkablity in the privacy considerations at https://www.ietf.org/archive/id/draft-ietf-oauth-selective-disclosure-jwt-10.html#name-unlinkability currently. Concrete suggestions to that text about how to better frame the risks and difficulties around Issuer/Verifier Unlinkability (perhaps especially with respect to something like a government issuer compelling collusion from verifiers) would be welcome for consideration.
>
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