Computer security researchers say that the GSM phones used by the majority of the world's mobile-phone users can be listened in on with just a few thousand dollars worth of hardware and some free open-source tools.

In a presentation given Sunday at the Chaos Communication Conference in Berlin, researcher Karsten Nohl said that he had compiled 2 terabytes worth of data -- cracking tables that can be used as a kind of reverse phone-book to determine the encryption key used to secure a GSM (Global System for Mobile communications) telephone conversation or text message.

While Nohl stopped short of releasing a GSM-cracking device -- that would be illegal in many countries, including the U.S. -- he said he divulged information that has been common knowledge in academic circles and made it "practically useable."

Full story: Computerworld