> If advertisers are getting information out of encrypted data, that means the encryption is broken.

I'm just suggesting that Facebook wants to use homomorphic encryption to tell your phone which adverts to download. It won't know which adverts it told you to download or why ... but it will know that you've downloaded them once you do.

It could in theory serve the adverts through homomorphic encryption, but then it wouldn't be able to invoice people based on how many times their adverts were served. I don't see that happening though.