GSM A5/1 Cellphone Encryption Code Is Divulged

Via NYTimes.com -

A German computer engineer said Monday that he had deciphered and published the secret code used to encrypt most of the world’s digital mobile phone calls, saying it was his attempt to expose weaknesses in the security of global wireless systems.

The action by the encryption expert, Karsten Nohl, aimed to question the effectiveness of the 21-year-old G.S.M. algorithm, a code developed in 1988 and still used to protect the privacy of 80 percent of mobile calls worldwide. (The abbreviation stands for global system for mobile communication.)

“This shows that existing G.S.M. security is inadequate,” Mr. Nohl, 28, told about 600 people attending the Chaos Communication Congress, a four-day conference of computer hackers that runs through Wednesday in Berlin. “We are trying to push operators to adopt better security measures for mobile phone calls.”

The G.S.M. Association, the industry group based in London that devised the algorithm and represents wireless companies, called Mr. Nohl’s efforts illegal and said they overstated the security threat to wireless calls.

“This is theoretically possible but practically unlikely,” said Claire Cranton, an association spokeswoman. She said no one else had broken the code since its adoption. “What he is doing would be illegal in Britain and the United States. To do this while supposedly being concerned about privacy is beyond me.”

Some security experts disagreed. While the disclosure does not by itself threaten the security of voice data, one analyst said companies and governmental organizations should take the same steps to ensure the security of their wireless conversations as they do with antivirus software for computer files.

“Organizations must now take this threat seriously and assume that within six months their organizations will be at risk unless they have adequate measures in place to secure their mobile phone calls,” said Stan Schatt, a vice president for health care and security at the technology market researcher ABI Research in New York.