It’s a technological arms race, pure and simple.

That’s how Jamie Bartlett, author of The Dark Net, sums up the constantly evolving battle in cyberspace between terrorists and the intelligence agencies trying to discover their hidden communications.

“The unbelievable growth in widely available (encryption) software will make their job much harder,” he said. “What it will mean is a shift away from large-scale traffic network analysis to almost old-fashioned intelligence work to infiltrate groups – more and people on the ground as opposed to someone on a computer in Cheltenham.”

In the Second World War there was Enigma, the German cipher machine eventually decoded by Britain. There was also steganography, the art of shrinking and concealing information inside objects such as microdots, usually only detectable by those who knew exactly where to look.

In Cold War days spies sat next to each other on park benches or left secret messages to be picked up later in “dead letter drops” behind objects such as flowerpots or in crevices in walls.

In the 1990s extremist groups used satellite phones and faxes to communicate, with paper messages from Osama Bin Laden in Afghanistan churning out of a fax machine operated in North London by his UK representative. Already that sounds almost prehistoric.

For close to two decades now the internet has been the river through which most terrorist communications flow, hiding amongst the legitimate, the ordinary, the innocuous or the just conventionally criminal.

The dark web sounds sinister and it certainly does hide a multitude of very dark dealings. But the sheer volume of ordinary people now using it as a matter of course have inevitably pulled it closer into the mainstream of digital communications.

The more people who use it, the easier, in theory, it will be for terrorists to hide their own messages amongst its terabytes of data. But the dark web does have benign uses and while it presents a growing challenge to counter-terrorism authorities this is a phenomenon that is unlikely to disappear anytime soon.

http://www.bbc.com/news/technology-31948818