Today, Nohl has published a how-to guide on how to crack the encryption, saying that users with a high-end PC, a radio and some easily downloaded software can record phone calls using the codes.
"The message is to have better security, not we want to break you," says Nohl of his decision to make the codebook available via file sharing sites. "The goal is better security. If we created more demand for more security, if any of the network operators could use this as a marketing feature ... that would be the best possible outcome."
The 64-bit A5/1 algorithm is 21 years old and has been protecting GSM networks since its implementation in 1988. Law enforcement has had the ability to intercept GSM calls for decades, and regular wiretapping is also possible. 3G networks use fully secure 128-bit A5/1, and the GSMA says they are gradually phasing out the A5/1 for the more secure A5/3.
Written by: Andre Yoskowitz @ 30 Dec 2009 14:08
