A system called “WiKey” presented at a conference last year could tell what keys a user was pressing on a keyboard by monitoring minute finger movements. Once trained, WiKey could recognize a sentence as it was typed with 93.5 percent accuracy—all using nothing but a commercially available router and some custom code created by the researchers.And a group of researchers led by a Berkeley Ph.D. student presented technology at a 2014 conference that could “hear” what people were saying by analyzing the distortions and reflections in wi-fi signals created by their moving mouths.