Cryptographer claims a cell phone can crack RFID tags

Feb 27, 2006 3:31 PM

Adi Shamir, professor of computer science at the Weizmann Institute in Israel, has applied power analysis techniques to crack passwords for the most popular brand of RFID tags.
Shamir discussed his findings at a panel discussion at the recent RSA Conference in San Jose, Calif., TechWeb reports.
In recent weeks, Shamir used a directional antenna and digital oscilloscope to monitor power use by RFID tags while they were being read. Patterns in power use could be analyzed to determine when the tag received correct and incorrect password bits, he explained to the panel.
"The reflected signals contain a lot of information," Shamir said. "We can see the point where the chip is unhappy if a wrong bit is sent and consumes more power from the environment...to write a note to RAM that it has received a bad bit and to ignore the rest of the string," he added.
"I haven't tested all RFID tags, but we did test the biggest brand and it is totally unprotected," Shamir said. Using this approach, "a cellphone has all the ingredients you need to conduct an attack and compromise all the RFID tags in the vicinity."
Shamir said the pressure to get tags down to five cents each has forced designers to eliminate security features -- a shortcoming he says needs to be addressed in next-generation products.

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