Audio one-time pad smart-card?

[A. Melon]

Hold the ComDot card, a new product from Tel Aviv-based ComSense 
Technologies Ltd., up to your computer's microphone and squeeze the slight 
bump in its center. Otherwise indistinguishable from a garden-variety 
credit card, it emits a high-pitched series of noises similar to that of a 
fax machine or dial-up modem. 

Because it communicates via sound, the ComDot doesn't require a 
specialized card reader like other "smart" cards -- only a computer with a 
sound card and a microphone. It is even designed to work over the 
telephone. 

[...]

The card transmits an encrypted identifying code via high-frequency sound 
waves -- a long screech, followed by a lower-pitched warble. The computer 
then verifies the ID with the ComSense servers; the user enters a PIN 
(personal identification number) for added security, and the log-in is 
complete. 

[...]

The ComDot itself consists of a three-year battery, computer processor, 
two speakers and a small amount of memory. It never emits the exact same 
tone twice, so even if someone trying to gain unauthorized access to 
patient files were to record the sound and replay it, they would not 
succeed. 

[...]

Not only could the ComDot sit inside a fraud-proof, ultra-secure credit or 
ATM card, but the technology could also be used to validate online 
commerce transactions. Instead of merely requiring consumers to type in 
their credit card number, they would squeeze their ComDots, and perhaps 
enter a PIN. 

[...]

http://www.cnn.com/2001/TECH/ptech/06/22/smart.card.reut/index.html