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 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 - he said he
divulged information that has been common knowledge in academic
circles and made it "practically useable." Intercepting mobile
phone calls is illegal in many countries, but GSM-cracking tools
are already available to law enforcement. Knoll believes that
criminals are probably using them too. "We have just basically
copied what you can alread