Weapons of Mass Surveillance: the international cyber arms trade giving governments the tools to spy on their citizens.

"It used to be 'walls have ears', now it's 'smartphones have ears'". Activist

The digital age has revolutionised the way we live our lives, giving us the tools to connect with people and share information in ways that would have previously been impossible. But this same technology has also given governments the ability to spy on their citizens on an astonishing scale.

"Every country willing to write a pay check to the right party can do this sort of surveillance but no one wants to admit it." Cyber security specialist

Cyber surveillance technology enables governments to collect, catalogue and analyse the communications of millions of people.

"You'd be able to intercept any internet traffic. If you wanted to do a whole country, go ahead." Former cyber security employee

This BBC investigation reveals a shadowy international trade in this cyber weaponry.

These companies are commercial players, (they) are developing these highly sophisticated technologies that could have a deep impact on our national security, on peoples' lives." European MP

From international arms fairs to highly classified manufacturing facilities, the program tracks how major weapons makers have branched out from producing conventional arms to cyber espionage tools, landing lucrative deals worth hundred of millions of dollars. Many of these deals are with countries run by repressive regimes.

"It's a trade-off. None of these countries have the same ethical, moral code as we do ... but we still do it. Every country therefore involves some form of compromise." Former Hd of Cyber Security, UK Ministry of Defence

In interviews with workers hired to carry out mass scale cyber espionage, the film shows how these tools are being used to shut down dissent.

"We focused on all the opposition. There were no exceptions." Former cyber security employee

Those targeted by highly invasive cyber surveillance say their lives have been shattered.

"Being watched is a horrible feeling. You lose your freedom because you cannot move. It's a violation of your privacy. It's like having a stranger in your bedroom." Activist

Weapons of Mass Surveillance, from the BBC, reported by Nawal Al-Maghafi and presented by Sarah Ferguson, goes to air on Monday 31st July at 8.30pm. It is replayed on Tuesday 1st August at 10.00am and Wednesday 2nd at 11pm. It can also be seen on ABC NEWS channel on Saturday at 8.00pm, ABC iview and at abc.net.au/4corners.