As founder and director of the University of Toronto's Citizen Lab, Ron Deibert has spent his career tracking down and uncovering some of the world’s most clandestine cyber espionage operations. Now, the cybersecurity expert is pulling back the curtain on this shadowy world in his new book, Chasing Shadows. Deibert tells David Common how our democracies have become vulnerable to these threats as we become more reliant on technology – and what we need to do to protect them.