Status of pending Protected Audience API capabilities

As we move Protected Audience API closer to general availability and approach third-party cookie deprecation in Chrome, you may be wondering about the availability of Protected Audience API services and features. Here you'll find a list of the scoped Protected Audience API features and when they'll be supported.

# Feature availability timeline

# Additional features

# Event-level auction win reporting

We initially indicated that the event-level auction win reporting would be a temporary solution, and Private Aggregation API will be used to generate summary reports. After listening to feedback and examining the relative complexity of aggregation-based solutions, particularly for billing, we have decided to not remove support for event-level auction win results reporting with reportResult() and reportWin() functions having the ability to call sendReportTo() until sometime after third-party cookie deprecation.

Event-level auction win reporting will be supported until at least 2026, and we will provide advanced notice before the API transitions to any alternative solutions.

Auction loss reporting will continue to be supported through the Private Aggregation API.

# Trigger-based aggregate reporting

During a Protected Audience auction, you can send an aggregatable report when triggered by an event using Private Aggregation API’s contributeToHistogramOnEvent() method. The triggering event can come from the auction itself, such as an auction win or loss, which allows you to generate an auction loss report. The event can also come from a fenced frame outside of the auction using Fenced Frame Ads Reporting API’s window.fenced.reportEvent() to trigger the aggregatable report submission.

See the contributeToHistogramOnEvent() section of the Private Aggregation page to learn more.

# Trusted Execution Environment usage for Key/Value service

The Protected Audience API Key/Value service allows the auction to retrieve real-time signals when the bid is generated by the buyer and the ad is scored by the seller. The Key/Value service will eventually be required to run in a trusted execution environment (TEE) to ensure that the user's data is kept private.

Running the Key/Value service in a TEE will not be required until sometime after third-party cookie deprecation. We will provide at least 12 months notice before TEE usage is mandatory. Until then, you can continue to use your own server for real-time key/value signals. Note that running the Key/Value service in a TEE with user-defined functions (UDFs) will be available for testing by the end of Q1 2023 with on-device Protected Audience API.

# Fenced frames

Fenced frames are a new HTML element that limits communication between the content and the embedder, and is used for rendering content based on cross-site data. The Protected Audience API will render content into a fenced frame.

After working closely with various stakeholders and examining the significant effort to accommodate this change, Chrome will not mandate fenced frames until at least 2026 to maintain ecosystem inclusivity,and Chrome will provide significant advanced notice. Until then, if fenced frames are not used, you will need to use an iframe to render the opaque URN. Also, it should be noted that sellers could still require the use of Fenced Frames.

# Improved Protected Audience API and Attribution Reporting integration

Recently, challenges have been pointed out around the integration of the Attribution Reporting API and Protected Audience API, especially where fenced frames are involved.

For event-level reporting with the Protected Audience API, we have a proposed set of initial improvements to make this integration easier which you can learn more about in the explainer. The integration will be available for both fenced frames and iFrames. Event-level reporting will be available for testing in Chrome Stable M112+.

For those who need Attribution Reporting with the Protected Audience API, we are working on more flexible solutions to capture more bidding signals with aggregatable reports, and we will publish a proposal once it is ready.

# K-anonymity

For a creative to be considered k-anonymous, the tuple of interest group owner, bidding script URL, creative URL, and creative size must meet the threshold of a crowd of 50 users per creative (k=50) within the past 30 days before the ad can be served. The creative is available to be served as soon as it hits the 50 users threshold and does not need to wait for 30 days.

The k-anonymity enforcement will be ramped up gradually. Later in 2023, we will begin to check the render URL for k-anonymity. Later in Q1 2025, we will begin to check the ad size in addition to the URL for k-anonymity.

You can learn more about the parameters from the k-anonymity explainer.

# Bidding and Auction Services

We have heard some concerns about Protected Audience API latency and are actively working on improving on-device latency. Both Chrome and Android plan to provide Bidding and Auction Services as an additional way to run bidding and scoring logic besides on-device auctions. Bidding and Auction services is a Protected Audience API service solution for running auctions off-device, which we believe will allow for even faster performance.

We will continue to support on-device auctions, and the use of the Bidding and Auction Services is not required unless it fits your use cases.

More details can be found in the blog post.

# What's next?

We want to engage in conversations with you to ensure we build an API that works for everyone.

# Discuss the API

Like other Privacy Sandbox APIs, this API is documented and discussed publicly.

# Experiment with the API

You can experiment and participate in conversation about the Protected Audience API.