Dear Lazyweb, what's the deal with security of iCloud-synched Notes on iOS 10?

In previous versions of iOS, Notes were synched via IMAP. This means that to store them in iCloud, you had to have iCloud email configured. I didn't, and don't, so I only had the option of storing my notes on my own IMAP server, not on iCloud. Which sounds fine, except that it was unreliable: if I edited the same note from more than one device, I would end up with duplicate copies of the note due to merge conflicts like half of the time. I never figured out how to reproduce this, but it was a constant hassle.

But with iOS 10 I see that I now have the ability to sync my Notes through iCloud without having iCloud email set up. This suggests to me that Notes are now synched to iCloud through some mechanism that is not IMAP, and that might therefore work more reliably, so I'm giving that a try to see how that works out.

My question is, do any of you know what that new mechanism is, and what kind of crypto is involved? Specifically, does this give apple the ability to read my Notes?

I am not asking "do they promise not to", I'm asking "do they have the ability to do so, e.g., in response to a subpoena." For example, I think the current belief is the Apple cannot intercept and decode the content of your iMessages, unless you are using iCloud to back up your phone instead of backing up to your Mac, in which case they can, because they can decode the copy of those messages that ends up in the iCloud backup. I am asking whether Notes fall under the "iMessage" crypto regime (private keys exist on the device, public keys on the server) or the "backup" crypto regime (Apple holds the private keys).

(If the answer is "Yes, Apple can read your Notes", that won't necessarily stop me from using iCloud for Notes sync, but I'd like to know.)

(Some of you are dying to tell me about some third party app that you like more than Notes. I am happy for you but please don't.)

Previously.