If the server could actually decode things it would’ve gotten something that could be decrypted into let’s say 15 phone numbers. A little bit like if they were hashed, to simplify.

So the answer the server returns isn’t who the phone number belongs to, it’s who those 15 phone numbers belong to.

And then the client can decrypt it and just get the one that it cares about.

But unlike if you were just doing hash buckets no one who saw the data going back-and-forth could actually understand any of it. Correct?

Is this only really good for data to look up cases? I had thought homomorphic encryption could be used to do actual calculations, at least certain kinds.