People have long worried about technology invading their lives. The front cover of Newsweek magazine, illustrated by a telephone, camera and tape recorder, once captured those fears, asking: “Is Privacy Dead?” The date: July 1970.

Since then, we have seen the mass introduction of personal devices such as laptop computers, smartphones and health monitors. Today, more than 6bn such devices are connected to the internet. According to Gartner, a technology research company, 5.5m are being added each day. Most of them are vulnerable to being hacked by those ingenious or devious enough. We truly live in a golden age of surveillance, in which every step we take and every heart flutter we make can be recorded, for better or worse.

Our governments are desperate for us to keep that information secure — but, understandably, they also want selective access to that mass of data when national security demands. The technology companies, which often stand between governments and users, have mostly been happy to comply with lawful requests for such data.