Comment by fragmede

Netflix being unable to know your watch history on their service is exactly the goal of homomorphic encryption. The technology to make that work at that scale does not exist, however for smaller bits of data, eg phone numbers, that's entirely possible!

With PIR, an Apple phone recieving a phone call queries Apple's database with that phone number, but because it's using homomorphic encryption, Apple doesn't know the number that called despite looking it up in their database to provide caller id info, so they can't tie your phone number and the callers phone number together.

https://machinelearning.apple.com/research/homomorphic-encry...