Digital security and its discontents—from Hillary Clinton’s emails to ransomware to Tor hacks—is in many ways one of the chief concerns of the contemporary FBI. So it makes sense that the bureau’s director, James Comey, would dip his toe into the digital torrent with a Twitter account. It also makes sense, given Comey’s high profile, that he would want that Twitter account to be a secret from the world, lest his follows and favs be scrubbed for clues about what the feds are up to. What is somewhat surprising, however, is that it only took me about four hours of...