@evan @jessamyn
Ah, ok, I was not incorrect in my thinking. They need to store at least your account identifier in the clear to be able to send it to matches. That and learning the phone number for at least as long as it takes to prove you own it and likely forever to be able to repudiate it later if you drop that number, it later gets reassigned, and the new owner wants to use it with the service. At that point the new user would want you to not 'have' it.
So not nothing but fairly minimal.