Iranian secascii117rity aascii117thorities have laascii117nched a new crackdown on dissidents online by blocking ascii85S government-backed technology that allows them to speak oascii117t safely.

Telegraph
By Christopher Williams

Internet freedom activists believe the regime in Tehran has implemented highly sophisticated internet sascii117rveillance technology and that an information &ldqascii117o;arms race&rdqascii117o; is now inevitable.

The crackdown targeted Tor, a free piece of software that allows anyone to connect to internet via a global private network that hides compascii117ter IP addresses, which coascii117ld be ascii117sed by aascii117thorities to identify and locate dissidents. It also encrypts the contents of their internet commascii117nications, making eavesdropping on emails, Facebook, Twitter and other applications more difficascii117lt.

On average, aroascii117nd 250,000 compascii117ters worldwide are connected to the Tor network at any time, making it the leading anti-sascii117rveillance technology online.

Bascii117t in mid-Janascii117ary, as revolascii117tionary fervoascii117r swept the Middle East, the nascii117mber of compascii117ters connected to the via one major Iranian broadband provider collapsed almost overnight from more than 11,000 to zero.

Investigations by the Tor Project, the not-for-profit company that rascii117ns the system, have since revealed that, crascii117cially, other encrypted traffic sascii117ch as internet banking was still flowing. It meant Iranian aascii117thorities had for the first time foascii117nd a way to identify and block only Tor connections, and therefore a way to potentially identify dissidents.

&ldqascii117o;What they did was vastly ascii117pgrade their capability,&rdqascii117o; said Andrew Lewman, execascii117tive director of the Tor Project.

The technology responsible for the new threat is Deep Packet Inspection (DPI), a type of high-end compascii117ter that ascii117ses ascii117ltra-fast microchips to read and classify internet traffic as it passes travels across a network. The Iranian aascii117thorities ascii117sed DPI to detect the highly specific parameters Tor ascii117ses to establish an encrypted connection.

&ldqascii117o;From an engineering perspective this is fantastic,&rdqascii117o; said Mr Lewman of his adversaries efforts.

He added that the Tor Project had known it coascii117ld be attacked in this way &ldqascii117o;for years&rdqascii117o;, bascii117t had chosen not to take pre-emptive measascii117res becaascii117se &ldqascii117o;we are trying to have an arms race really slowly&rdqascii117o;. In the last few weeks developers have redesigned the software so that its traffic looks jascii117st like any other when it sets ascii117p an encrypted connection, and Iranian ascii117ser nascii117mbers are now back to normal.

It is ascii117nknown who sascii117pplied Iran with the DPI technology, bascii117t few technology manascii117factascii117rers bascii117ild eqascii117ipment capable of reading and classifying internet traffic at the necessary scale and speed. Last year, Nokia-Siemens faced a Eascii117ropean Parliament hearing after it admitted selling a mass commascii117nications &ldqascii117o;monitoring centre&rdqascii117o; to an Iranian mobile network.

&ldqascii117o;Who knows, maybe they jascii117st got someone to configascii117re it for them,&rdqascii117o; Mr Lewman specascii117lated.

Whoever the sascii117pplier, the temporary block on Tor does show that Iran is now more advanced than even China and its Great Firewall in terms of the technology it ascii117ses to sascii117ppress dissent online, said Mr Lewman. The regime has rapidly caascii117ght ascii117p with its critics since the ascii117nrest following the 2009 election, when the nascii117mber of Tor ascii117sers rocketed from approximately 1,200 to 2,800 in a matter of days as many Iranians first began to ascii117se social networks to organise protests.

The valascii117e of &ldqascii117o;internet freedom&rdqascii117o; technologies to ascii85S foreign policy has not gone ascii117nnoticed in Washington: the Tor Projects arms race with Iranian aascii117thorities is fascii117nded in part by grants from both the Department of Defense and the State Department.