The Associated Press
B E R K E L E Y,   Calif.,   April 14 — It was a challenge a trio of computer students and professionals could not resist: proving "tamperproof" digital cellular phones are actually vulnerable.
     After about six hours of work, two graduate students at the University of California at Berkeley and a computer cryptologist were able to "clone" the phone, allowing them to make unauthorized calls from another phone.
     "Given the state of the security of other cellular phone systems, I wasn't terribly, terribly surprised," said Ian Goldberg, one of the students. The three looked at the project as a challenge.
     USA Today reported the breakthrough on Monday.
     Still, the amount of time and effort it took to clone the codes makes the digital phone security much more difficult to circumvent than analog cellular phones, which in comparison are easily breached.

GSM Standard Cracked
The three cracked the codes guarding a Global System for Mobile Communications, or GSM, phone. The GSM digital standard is the most widely used in the world, with more than 79 million phones in use.
     Overcoming the security also revealed a hint that the code may have been intentionally weakened during its design to allow government agencies the ability to eavesdrop on telephone conversations, The New York Times reported today.
     Marc Briceno of Smartcard Developers Association, who worked with Goldberg and student David Wagner, said the weakened code would let powerful computers available to intelligence agencies decode a voice conversation relatively quickly.
     "I can't think of any other reason for what they did," Briceno said.
     For years, the computer industry has been rife with rumors about government intrusion or intimidation. Little evidence has ever emerged to support such speculation, the Times reported, but the origins of the GSM system are hazy.