Mobile calls may not be private

A German computer scientist has released details about breaking the secret code used to protect the conversations of more than 4 billion mobile phone users.

Karsten Nohl, along with other experts, spent five months trying to break the algorithm used to encrypt calls using GSM technology, the most popular standard for mobile phone networks all over the world. gender.

Nohl told a media conference in Berlin that his work shows that GSM security is still flawed.

He said: 'We are trying to warn everyone of this common weakness. Along with consumer demands, we hope to create some pressure for better coding. '

The GSM Association (GSMA) that created the algorithm and supervised the development of this standard said that Nohl's work was highly illegal in the UK and many other countries.

But Nohl said he consulted lawyers before announcing it and believed it was legal.

GSM encryption was first introduced in 1987 and has become the main tool for encrypting mobile conversations.

$ 30,000 can eavesdrop on all mobile conversations

Karsten Nohl along with a few dozen others announced the material they announced will break the A5 / 1 algorithm, a 22-year-old code used by many manufacturers. In 1994 a series of weaknesses of this system were published.

Karsten Nohl, who claims to be a "security researcher before the attack", also announced his intention to break the code at the Hacking conference at Random (HAR) in the Netherlands in August 2009.

He said: 'Any cryptographic function is a key to open. You cannot decrypt without a secret key ' . To do this, Nohl and his colleagues use computer networks to break code through 'every clue' they get about the input and output of the code.

All the clues are listed in a list that, according to Nohl's description: 'It's like a phone book, if someone tells you a name, you can look up their number.' .

He said using just this code manual and a healthy computer and a $ 30,000 radio device would allow anyone to decode the signals from billions of GSM users around the world.

Anyone, including criminals, only needs $ 30,000 to solve the A5 / 1 algorithm.

GSM is no longer safe

Many experts said that previously it was possible to decode GSM signals for eavesdropping on conversations, but the investment in equipment had to be in the hundreds of thousands of dollars.

According to Ian Meakin of cell phone encryption company Cellcrypt, " only government agencies and large funded crime organizations have access to the necessary technology."

He said Nohl's work was a "major concern" because it reduced the cost of decoding GSM calls. Unknowingly, it can put these tools and technologies into the hands of criminals.

However, GSMA rejects worries. They argue that there have been many sketches on how to violate A5 / 1 so far, but so far there has been no actual attack.

The association also said it is proposing to upgrade A5 / 1 to a new, more secure standard called A5 / 3, which is currently under construction.