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ietf-wg-spice / draft-ietf-spice-sd-cwt

SPICE SD-CWT
https://ietf-wg-spice.github.io/draft-ietf-spice-sd-cwt/intialize-draft-contents/draft-ietf-spice-sd-cwt.html
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privacy considerations should include linkability or unlinkability, and the associated use cases #27

Open npdoty opened 2 weeks ago

npdoty commented 2 weeks ago

Privacy considerations are currently missing from this draft, but could use some extensive documentation.

But most urgently, the draft should be clear about whether selective disclosure also reveals linkability across different verifiers, or not. What is revealed about the issuer is also a separate disclosure, as well as a potential source of linkability. It sounds like there might be some significant use cases where linkability and selective disclosure is desirable, though age verification might not be one like that.

For many use cases, particularly on the web, linkability across verifiers (or between colluding verifier and issuer) is a particular privacy concern and unlinkability is a desirable property. The draft should make it clear which properties are provided.

OR13 commented 2 weeks ago

The privacy considerations for sd-cwt are very similar to that of sd-jwt, @npdoty do you think we should use a reference, or would you like us to propose alternative framing of these considerations?

If you have a chance to review the sd-jwt considerations, I welcome any comments on where we should add more or less text.

Hope to see you in person at a future IETF.

Denisthemalice commented 6 days ago

I raised several issues during the last call from SD-JWT.

(# 514) A section should be added to consider the case of a presentation of claims to Verifier that have been issued by different Issuers (https://github.com/oauth-wg/oauth-selective-disclosure-jwt/issues/514)

I sent an update of this issue: (# 529) Update of Issue #514 (new section 9.12) for the support of Post Quantum cryptography (https://github.com/oauth-wg/oauth-selective-disclosure-jwt/pull/529)

(# 515) The term "unlinkability" is overloaded. For more clarity, the wording "End-user intrackability" should be used in addition (https://github.com/oauth-wg/oauth-selective-disclosure-jwt/issues/515)

(# 516) A new section about "End-User intrackability" should be added (https://github.com/oauth-wg/oauth-selective-disclosure-jwt/issues/516)

These contributions can be used to fill-in the Privacy Considerations section.