Proposing updates to First-Party Sets based on community feedback and upcoming WICG call

Hi Privacy Community Group members,


First-Party Sets is a proposal that was previously incubated in this forum,
and has since moved to the WICG [1] for further development.


We wanted to inform you all that we are proposing changes to the proposal
[2] in response to the feedback received from this group.


Here is a high-level summary of the proposed changes, but we encourage you
to read the proposal for additional details:

   -

   Leverage the Storage Access API [3] for sites to request cross-site
   cookie access, instead of the SameParty attribute [4].
   -

      This is in response to feedback from browser implementers that
      cross-site cookie access by default within a FPS poses privacy concerns,
      and that a mechanism like the Storage Access API is preferred to mediate
      such access.
      -

   Define a set through use-case-specific "subsets" [5]. Each subset
   category will have its own requirements, and browser handling approach.
   -

      Since each type of "subset" has a different set of considerations
      around user understanding and ability to run technical checks for
      conformance to requirements; a more granular approach allows us to
      implement controls relevant to each category.

If you are interested in further discussion, we are organizing a WICG call
on Wednesday, August 17 2022, at 9am PT/12pm ET/6pm CET. Please see [6] for
more information on joining this and future calls. As always, you are also
welcome to engage via issues on the repository.


Thank you,

Kaustubha Govind, on behalf of First-Party Sets editors


[1] https://www.w3.org/community/wicg/

[2] https://github.com/WICG/first-party-sets/issues/92

[3]
https://github.com/krgovind/first-party-sets#leveraging-the-storage-access-api

[4] https://github.com/cfredric/sameparty

[5]
https://github.com/krgovind/first-party-sets#defining-a-set-through-use-case-based-subsets

[6] https://github.com/WICG/first-party-sets/issues/89