gasoline and toll-booth "pass" accounts and car-key ignition locks!
(From
http://www.nytimes.com/2005/01/29/national/29key.html?pagewanted=2&oref=login )
"Graduate Cryptographers Unlock Code of 'Thiefproof' Car Key
By JOHN SCHWARTZ January 29, 2005
{A team at Johns Hopkins} has cracked the security behind "immobilizer" systems from Texas Instruments Inc. The systems reduce car theft, because vehicles will not start unless the system recognizes a tiny chip in the authorized key. They are used in millions of Fords, Toyotas and Nissans. All that would be required to steal a car, the researchers said, is a moment next to the car owner to extract data from the key, less than an hour of computing, and a few minutes to break in, feed the key code to the car and hot-wire it.
The implications of the Hopkins finding go beyond stealing cars. Variations on the technology used in the chips, known as RFID for radio frequency identification, are widely used. Similar systems deduct highway tolls from drivers' accounts and restrict access to workplaces.
The Johns Hopkins researchers say that if other radio frequency ID systems are vulnerable, the new field could offer far less security than its proponents promise. ... Aviel D. Rubin, a professor of computer science who led the team, said that if criminals did eventually duplicate his students' work, PEOPLE COULD BLOCK EAVESDROPPERS BY KEEPING THE KEY OR SPEEDPASS TOKEN IN A TINFOIL SHEATH WHEN NOT IN USE."