Your phone can see dozens of WiFi networks right now. So can mine. If we're in the same area, we're probably seeing many of the same networks. Can we use that overlap to discover each other without either of us revealing which networks we actually see? Without directly communicating in that particular environment? This is the core idea behind Shimmer: devices discover nearby peers by comparing their environments cryptographically, without disclosing the raw details. Instead of broadcasting "I se...