Email can be a vulnerable way to communicate, especially if you're sending around valuable information because you're a politician or a journalist or an activist. High-profile email users are targets for hackers, trying to get them to click the wrong link and give up their passwords. Google offers a version of Gmail with extra security — you need a physical USB key to log in. Anyone can use it, but Google markets it to high-profile users. Mark Risher, head of Google's Account Security team and a creator of its Advanced Protection Program, talked to Molly Wood about it.