It is not the first time someone has claimed to crack GSM’s encryption. German researcher, Karsten Nohl revealed that he and his team managed to break the code that is used in most cellular networks around the world.
In his presentation at the Chaos Communication Conference in Berlin, the largest hackers conference in Europe, Nohl said that his team took five months of work to crack the security algorithm that protects Global System for Mobile communications or better know as GSM.
Using trillions of mathematical possibilities, a codebook has been developed comprising 2TB of data and compiled into cracking tables. With this codebook, the encryption algorithm called A5/1 developed by the GSM Association (GSMA) can be cracked and anyone could eavesdrop on communications using about USD30,000 worth of computer hardware with some free open source tools.
Over the past few years, a number of academic papers have explained in theory, how the 20-year old A5/1 algorithm could be compromised. The GSM Association (GSMA) responded that so far there has been no real attack developed against A5/1 that can be used on commercial GSM networks. However it recognizes that A5/1 needs to be replaced, and is in the process of deploying a new security algorithm called A5/3.
GSM has been around for 21 years and was first cracked in 1994. Currently, there are over 4 billion active mobile phone users on the GSM network all around the world, making up about 80 percent of the mobile market. A demonstration of the technique by Nohl and his team is scheduled for tomorrow.