> Or, wait, you're going to centrally store these keys? No necessarily. Three alternatives are common: Data is encrypted with a key only the actor owns. Works

> Or, wait, you're going to centrally store these keys? No necessarily. Three alternatives are common: Data is encrypted with a key only the actor owns. Works for cases where that actor is the only one who should access it (I Reveal My Attributes type of schemes) Data is encrypted with a sum (combination) of the key from an actor plus some other actors have: only you and the recipient can decrypt. Works for cases like messaging or p2p data exchange. Data is encrypted with a OR of the key from an actor plus one by a trusted proxy: proxy and actor have ability to decrypt. This is closest the "centrally" storing. With the difference that "proxy" allows for a little more flexibity -in theory-.