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patcg-individual-drafts / private-aggregation-api

Explainer for proposed web platform API
https://patcg-individual-drafts.github.io/private-aggregation-api/
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Consider reducing maximum number of contributions per report #32

Closed alexmturner closed 1 year ago

alexmturner commented 1 year ago

We plan to pad the encrypted payload, which will increase the size of the payload. To mitigate this size increase, we're considering reducing the number of contributions allowed in each report (e.g. from 50 to 20).

Note also that currently, any additional contributions would be dropped, but we could also consider allowing batching of contributions into multiple reports if this maximum value is limiting. Please let us know if you have any thoughts!

csharrison commented 1 year ago

How large will the padded payload be?

alexmturner commented 1 year ago

The encrypted payload currently has size around 76 + #contributions*36 bytes, i.e. ~1.9 kB for 50 contributions and ~800 B for 20 contributions.

We also might be able to compress our representation (eliminating the "bucket" and "value" strings) to get the per-contribution factor down to 21 or 23 bytes, i.e. ~1.1 or ~1.2 kB for 50 contributions and ~500 B for 20.