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