But the good thing about using EKS is that the underlying system could be used for a lot more than this. We could have "blogs" that are tagged with a single string for keyword search, and let only the owner of the blog edit it (over the mix network) but anybody else gain access to it via EKS. We can also have arbitrary files uploaded via the mix network and downloaded via EKS with actual keyword searches, where the user types in the keyword to search for, more similar to P2P filesharing networks of the past (although it wouldn't be appropriate to use it for large files). The EKS also totally removes the need for a trusted nymserver like Pynchon Gate requires, which allows it to be used for group communications without having the risk of social network analysis, and also without being infeasible from a bandwidth perspective. So EKS is a huge advantage over PIR, but it is also hugely more difficult to implement (I could implement the PIR from pynchon gate in a day).