AS DETAILS of American snooping spread, sales of “1984”, George Orwell’s fable of an ever-watching state, rocketed. So did traffic to websites run by Tactical Technology Collective, a charity that teaches journalists and activists how to evade online spies. “It can be hard to persuade people surveillance matters to them,” admits Stephanie Hankey, a co- founder. Apparently not any more.

Dissenters have always taken laborious measures to cloak compromising communications. But computers now flag suspicious patterns in quotidian activities too. That requires greater vigilance from the most committed clandestines, who face three challenges.

The first is stopping the nosy sniffing communications in transit. Unencrypted e-mails are as open as postcards, warns Ben Wagner, an internet specialist at the European University Institute. Pretty Good Privacy (PGP), scrambling software that works with several web clients, can prevent such snooping.

Another task is to stop spooks sucking data from wherever it is stored. That means withdrawing from services, such as social networks and search engines, that must pass data to governments—or seeking out alternatives in untouchable territories. A battered desktop with free software makes a secure e-mail server. True coverts strip proprietary operating systems from their devices (a compromised one can access all your files).

It is trickier to elude systems that record whether communications have taken place. “Using a mobile is the worst thing you can do,” says Marek Tuszynski at Tactical Technology. The call logs kept by telecoms firms are difficult to dodge. Internet users have more security. Free software such as Tor can hide their identity by cleverly routing their requests.

But staying under the radar is tedious and hard to keep up. Clueless contacts can blow your cover. Even technophiles may compromise themselves by simpler means. Google’s Chrome browser, which offers a very basic private mode, wryly warns its users to beware of “people standing behind you”.

Ms Hankey would prefer laws, not just technology, to preserve people’s privacy. She wants governments in Europe and elsewhere to boost alternatives to America’s “digital monopolies”. Mr Wagner commends caution: “Perhaps some things shouldn’t be online at all.”