The Key Value Service (TKV) V2 protocol is available in Chrome Stable for on-device Protected Audiences auctions. We recommend testing the V2 protocol for existing developers who've deployed BYOS and expect key-value to be part of their long-term PA design. This is an optional, early-access opportunity for developers.

This enhanced protocol replaces the plaintext HTTPS communication of the existing "Bring Your Own Server" (BYOS) model with encryption, significantly improving user privacy. This is a key step in our journey to transition from BYOS to a privacy-advancing, TEE-based key-value service.

Key benefits of the new protocol:

• Enhanced Privacy: Encryption ensures that sensitive user data remains protected.
• Future-looking: Gives adopters the opportunity to begin migrating to TEE-based key-value services before they're required.

Adtechs are encouraged to evaluate TKV during this phase to:

• Familiarize themselves with the technology: Gain experience with this new solution for providing real time signals for Protected Audience auctions.
• Provide feedback: Contribute to the direction of TKV by offering insights and suggestions.
• Prepare for future changes: Ensure a smooth transition from BYOS.

To start using the feature, follow the steps below:

1. Onboard and deploy a TEE KV server.
2. Users can set up flags and configurations to enable the feature via the command line:

chrome --enable-privacy-sandbox-ads-apis --enable-features=FledgeTrustedSignalsKVv2Support --disable-features=EnforcePrivacySandboxAttestations,FledgeEnforceKAnonymity

3. Once Chrome has started, users can check if the feature is enabled within the context of a web page by running the following code:

navigator.protectedAudience && navigator.protectedAudience.queryFeatureSupport(
    "trustedSignalsKVv2")

4. For buyers to use this feature to fetch real-time bidding signals, set 'trustedBiddingSignalsURL' and trustedBiddingSignalsCoordinator fields when joining interest groups. For example:

const myGroup = {
  'owner': 'https://www.example-dsp.com',
  'name': 'womens-running-shoes'
  ...
  'trustedBiddingSignalsURL': ...,
  'trustedBiddingSignalsCoordinator': 'https://www.publickeyservice.com',
  ...
}

5. For sellers to use this feature to fetch real-time scoring signals, set 'trustedScoringSignalsURL' and trustedScoringSignalsCoordinator fields in auction configuration. For example:

const myAuctionConfig = {
  'seller': 'https://www.example-ssp.com',
  'decisionLogicURL': ...,
  ...
  'trustedScoringSignalsURL': ...,
  'trustedScoringSignalsCoordinator': 'https://www.publickeyservice.com',
  ...
}

6. There are two default coordinator endpoints which can be applied to 'trustedBiddingSignalsCoordinator' and 'trustedScoringSignalsCoordinator':
   1. GCP: https://publickeyservice.pa.gcp.privacysandboxservices.com
   2. AWS: https://publickeyservice.pa.aws.privacysandboxservices.com

Please engage and share feedback by replying to this issue or in other ways you prefer.