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The NSA can decrypt and listen to phone calls

Not even 4G phones are safe
Mon Dec 16 2013, 16:56

THE NOT SO SECRET US National Security Agency (NSA) has managed to decrypt the cypher used for many mobile phone communication and therefore can listen to phone calls.

While decryption by military and law enforcement agencies has long been possible, one significant difference is that the latter are forbidden by law to tap into phones without a court order.

According to the Washington Post, the fact that one intelligence organisation is able to tap phones on this unprecedented scale suggests that others around the world can too.

Part of the problem is that while many networks use up to date protocols for data such as LTE and HSDPA, voice calls are still carried over older and less secure 2G services.

The key to network encryption is the A5/1 cypher that is used to transmit mobile phone signals. It appears from one of Edward Snowden's leaked documents that this has been cracked without the key. "At that point, you can still listen to any [individual person's] phone call, but not everybody's," said Karsten Nohl, chief scientist at Security Research Labs in Berlin.

The highest profile victim of this decryption in action is German Chancellor Angela Merkel, whose phone calls were intercepted by a listening post on top of the US Embassy in Berlin.

Although proof of concept demonstrations of A5/1 decryption have been taking place for the past 10 years or so, this is the first time that the extent of it has been fully realised, and it raises the point that if friendly nations can manage this, hostile countries almost certainly can as well. µ


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