Private Aggregation for Shared Storage M119 update

[Kevin Lee]

The following Private Aggregation API changes for Shared Storage will be live on M119 Canary by Monday Oct 2nd and will be available in the M119 Beta and Stable releases:

• Debug mode eligibility

  • The debug mode is only available to callers that are allowed to access third-party cookies. If the caller does not have access to third-party cookies, the debug mode will silently fail. This also means that when third-party cookies are deprecated, the debug mode will no longer be available. 

  • This change is backwards incompatible for callers using enableDebugMode() without third-party cookie eligibility.

• Report payload padding

  • To avoid the payload size being dependent on the number of contributions, the aggregatable reports will be padded with null contributions to a fixed length

  • This change will increase the size of the payload sent to the reporting endpoints, and the reporting endpoints using plaintext debug payloads will need to handle the null contributions added. 

  • This change is compatible with existing aggregation service versions.

• Reducing delay: 

  • When a context ID is specified, we remove the randomized 10-60 minute delay, which is superfluous as a report is always sent in this case. Instead, we wait until 5 seconds after the Shared Storage operation was started. Additional contributions after those 5 seconds will not be allowed. 

• Null report fixes

  • Currently reports with no contributions are inadvertently dropped. With the fix, when a context ID is specified, a null report is sent even if the budget is denied. Separately, it fixes a bug causing the budget to always be denied for null reports.

  • This change will increase the number of reports sent to reporting endpoints, and the reporting endpoints using plaintext debug payloads will need to handle the null report case.

If you have any questions or comments, reply to this post or open an issue in the Privacy Sandbox Dev Support repository on GitHub.