Four UK men arrested in Silk Road drugs bust as NSA targets Tor

'We know where you are, what you are doing and we will catch you,' vows new National Crime Agency boss

The crackdown on illicit goods trading website Silk Road has continued today with the arrest of four men in the UK on suspicion of drug dealing. More arrests are expected to be made in the coming weeks.

The newly formed National Crime Agency (NCA) today warned that pursuing the people behind such sites would be a "key priority" for the organisation, which reports to the Home Secretary.

The director general of the NCA, Keith Bristow, said that the arrest of the four UK-based Silk Road traders was proof that "the hidden internet isn't hidden and your anonymous activity isn't anonymous. We know where you are, what you are doing and we will catch you".

The arrests follow the apprehension in San Francisco, California of Ross William Ulbricht, the hacker reportedly responsible for the Silk Road website. Ulbricht was also known as "Dread Pirate Roberts" on the website.

Ulbricht is facing charges of money laundering, drug trafficking, hacking and soliciting a murder.

Silk Road was accessible via Tor, the encrypted browser developed more than 10 years ago by the US Naval Research Laboratory, before it became the responsibility of the Tor Foundation, a non-profit open-source software project.

As of 2012, 80 per cent of the Tor Project's $2m annual budget comes from the US government, with the Swedish government and other organisations providing the rest.

According to The Guardian newspaper, rumours in hacker circles are that the National Security Agency helped the CIA to track down the location of the Silk Road servers - reportedly in Iceland, but possibly also either Latvia or Romania - and to hack the website in a bid, not just to track down its ultimate owner, but also to glean information about its users.

That enabled the speedy arrests in the UK today.

The Tor browser, despite being developed by the US military, has been the target of hacking efforts by the NSA, according to the latest documents leaked by whistleblower Edward Snowden.

However, it has not yet fully cracked the software. One of the leaked documents states: "We will never be able to de-anonymize all Tor users all the time... With manual analysis we can de-anonymize a very small fraction of Tor users."