Hi all,

The Aggregation service team is seeking feedback on the following proposed limits for adtechs onboarding to cloud providers. This is to limit privacy leaks and/or exploitation by a bad actor.

Number of cloud providers per adtech:

Adtechs can specify their cloud deployment option using the coordinator origin when running Aggregation Service with Attribution Reporting API or Private Aggregation API. The coordinator origin includes the cloud provider in clear text which presents a risk of information gain by a bad actor. This opportunity for info gain increases as we increase the number of supported cloud providers. To minimize the risk of abuse, we propose the following:

• Adtechs can only be onboarded to 1 cloud provider at a time on Aggregation Service, with the exception of a migration window where adtechs may need to use 2 cloud providers simultaneously to generate summary reports. This limits the risk of bad actors identifying which cloud provider was used to generate summary reports for a subset of users.

Cloud migration:

We propose the following limits for cloud migration to allow adtechs to do testing and ramp up when migrating from one cloud to another, and to minimize risk of abuse:

• A migration window of 2 months. This window starts when adtechs first onboard on the destination cloud and is intended to give adtechs sufficient time to do testing on the new cloud and a slow migration from the source to destination cloud. After the migration window, the adtech will be offboarded from the source cloud. We would notify adtechs prior to migration window closing.
• Adtechs can be enrolled in a max of 2 providers during the migration window. Outside of migration, adtechs will be allowed enrollment in a max of 1 cloud provider.
• Adtechs will be allowed a max of 2 migrations in the past 365 days. Rollback will be considered a migration and would count towards this limit.

We welcome feedback on these limits. In particular:

• The proposed migration window of 2 months
• Any adtech use cases that may require more than 1 cloud provider outside of a cloud migration