K-anonimity - enforcement, timeline

[jonasz]

Hi,

The February blogpost mentioned that k-anonimity would be "available for testing later in 2023 Q3". As we are approaching Q3, it'd be great to clarify the plan in more detail. In particular, will k-anonimity be enforced during mode a and mode b testing phases? If so, with what k? These testing phases will work with sub 1% amount of traffic, so it's hard to imagine any k that wouldn't impact performance significantly. Of course there could be other approaches to the initial testing of k-anonymity than strict enforcement, and I was wondering if you have any plans / thoughts on that.

Best regards Jonasz

[JensenPaul]

@itaysharfi may have answers

[itaysharfi]

I expect to release the final enforcement plan soon. In the meantime, I can confirm that we will not be enforcing any K on mode A/B traffic during the testing period. More information will be coming soon.

[itaysharfi]

Hi @jonasz ,

We just published the timeline at https://developers.google.com/privacy-sandbox/relevance/protected-audience-api/k-anonymity

Best, Itay

[martinthomson]

@itaysharfi, that article says two different things about the ad size inclusion. The table says "Sometime after 2025", which I read as "t>=2026-01-01". The text later says "Not before 2025, we will begin to check k-anonymity for the ad size", which I read as "!(t <2025-01-01)" or "t >= 2025-01-01". Then you say "Ad size won't be a part of the k-anonymity check until at least 2025" which is more clearly "t >= 2025-01-01". The table is probably incorrect on that basis, but I wanted to check.

[itaysharfi]

We plan to enforce K-anon on ad sizes in Q1 2025 or later

@kevinkiklee for doc clarity issue

[jonasz]

Thanks for the details, Itay!

I have some follow up questions:

1. When the doc says "creative", does this apply to both an ad and an adComponent? (In other words: does this plan apply equally to ads and adComponents, or are there any differences we should be aware of?)
2. One of the steps is:

   In Q1 2024, for up to 20% of Chrome Stable traffic, excluding Mode A and Mode B experimental traffic, we will begin to check k-anonymity with the same parameters.

I was wondering, is that available as of now?

[brusshamilton]

1. When we say "creative" this applies to both ads and adComponents. There is a difference between the two however. The ad URL has to be jointly k-anonymous with the interest group owner and the bidding script URL. The adComponents only require that the adComponent URL be k-anonymous.
2. Currently we are in the process of ramping up k-anonymity enforcement, so we haven't yet reached 20%. Enforcement is currently enabled at 5%, and we plan to continue to ramp up further in the next few weeks.