I hadn’t really looked at this article on MasterCard selling your purchase data to Google, except to note that some were speculating about their BS “double blind encryption” claims. bloomberg.com/news/articles/…
I say the claims are BS because without details they’re exactly that. If I perform surgery on you without washing my hands first, I don’t get to claim some secret “double germ-free hands” technique. Give verifiable details or get out.
People are speculating this is some sort of Private Set Intersection technique, and that’s possible. Various folks at Google have written *research papers* on these techniques. But as far as I know, they didn’t scale to data this size.
This is an area where almost every simple thing you do with encryption is going to provide terrible user privacy, and the useful things are very very hard to do.
Given the talent and resources at Google it’s not *impossible* that they’ve developed a system that does secure multiparty computation at a never-previously-seen level of scale. However...
From a scientific point of view, this is like reading (in a footnote) that Google & MasterCard are protecting your data in their secret moonbase.
