> clients upload once and successively finer resolutions of the same aggregate can later be authorized without renewed client participation. That sounds less like ordinary secure aggregation and more like secure aggregation plus a delayed release mechanism, because the privacy story now leans on the release controller never colluding with the server. I’d want the failure modes spelled out pretty hard, especially what a malicious or compromised controller learns when it authorizes a layer, and whether earlier coarse releases can be combined with later ones to back out more than the paper intends. “Uploaded once” is the easy part, the part that matters at 3am is what happens when one of the two non-colluding parties is flaky or hostile.