Cryptanalytic attack on an RFID chip

[Steven M. Bellovin]

Steve Bono, Matthew Green, Adam Stubblefield, Ari Juels, Avi Rubin, and
Michael Szydlo have successfully attacked a cryptographically-enabled 
RFID chip made by Texas Instruments.  This chip is used in anti-theft 
automobile immobilizers and in the ExxonMobil SpeedPass.  You can find 
details at http://www.rfidanalysis.org/ (and a link to the draft paper),
and a New York Times article at http://www.nytimes.com/2005/01/29/national/29key.html

The paper itself is very nice, and combines RF techniques, 
cryptanalysis, Internet sleuthing, space-time tradeoffs, and more.  
There are some points I'm sure we'll be discussing at length, such as 
the authors' decision to withhold some of the details of their attack, 
the actual effective range of an RFID transponder when the attacker 
uses a suitable antenna, and the practical significance of the work.  
But oddly enough, what struck me was TI's response: rather than 
attacking the researchers, they co-operated, to the extent of providing 
them with challenge keys to see if the technique was really that 
effective.  TI is to be congratulated -- such a response is all too 
rare.

Btw, the paper suggests carrying car keys or SpeedPasses in aluminum 
foil.  I suspect that a more practical form factor is a spring-loaded 
conductive sleeve that normally surrounds the RFID chip, but is push 
back either manually or on key insertion.

		--Prof. Steven M. Bellovin, http://www.cs.columbia.edu/~smb



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