The designs of today's common online services (social networks, media streaming, messaging, email, etc.) are in conflict with privacy. Indeed, there have been many incidents (hacks, accidental disclosures, etc.) where private information has leaked.

My research aims to build systems that provide strong privacy guarantees and are practical (that is, have functionality and costs comparable to that of the status quo). In the talk, I will describe the challenges in building such systems and and how I address them. As an example, Popcorn is a Netflix-like media delivery system that provably hides (even from the content distributor) which movie a user is watching, is otherwise consistent with the prevailing commercial regime (copyrights, etc.), and achieves plausibly deployable performance (the per-request dollar cost is 3.87 times that of a non-private system).