Rogers investigating risk of ‘sandwich attack’ eavesdropping on cellphones

Following a cryptography investigation by researchers in Israel, Rogers Communications is looking at whether its consumers’ cellular phone conversations are open to an eavesdropping hack. Israeli researchers published a report on Jan. 12, in which they described hacking the A5/3 encryption on Global System for Mobile (GSM) communications phones. In Canada, 6.2 million subscribers to Rogers and Fido use GSM technology. “Rogers is investigating any risk, however no customers have been affected,” Rogers corporate communications manager Carly Suppa told The Wire Report by email. But it is almost impossible for Rogers to know whether its customers have been affected, Al Hawtin, vice-president of marketing and business development at Elliptic Technologies, said in an interview. “Your calls could have been intercepted, information could have been gleaned,” Hawtin said. “They don’t know .” Hawtin said the A5/1 and A5/3 GSM ciphers used to encrypt phone calls are over 20 years old and in need of an upgrade. “They should have done this quite a while ago,” Hawtin said, adding that upgrading the current security system would be costly. “Think of all the base stations out there. There are three billion handsets out there, and you need to upgrade them all.” In the report, researchers described how they broke the GSM A5/3 cipher using a "related key attack," in which a message is first encrypted using one key and is then changed to one or more keys. The hack, which has three components, is also known as a “sandwich attack.” The GSM Association, an international industry group representing GSM users, told The Wire Report in an email that there is no cause for concern. “The attack described in the paper has no effect on the security of A5/3 when it is used in GSM networks, and it remains secure,” spokeswoman Claire Cranton said. She added that “the attack is not against the A5/3 cipher as a whole, but against a component of A5/3,” and that “related key attacks are impossible to carry out in the context of GSM and A5/3.” Cranton did not reply to a follow up question asking whether the hack opens GSM phones to potential eavesdropping. Fido did not return calls.

Rogers investigating risk of ‘sandwich attack’ eavesdropping on cellphones

News | January 26, 2010

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