Locking In Brand Loyalty

MAKERS OF LAPTOPS, CELL PHONES, AND OTHER consumer gear want users to stick with their brands when they buy add-ons such as battery packs or expansion cards. It's a way to ensure quality, manufacturers say. It also lets them charge a premium for accessories.

Next month, their mission could get a lot easier, thanks to a new chip from EXEL Microelectronics Inc., a San Jose (Calif.) subsidiary of Japan's Rohm Co. EXEL's new chip uses the same "challenge-and-response" encryption tricks that Net surfers use to protect E-mail. When a new battery is plugged into an EXEL-protected cell phone, for example, an EXEL chip embedded in the battery performs an electronic "handshake" with a corresponding chip in the phone. In that handshake, the phone chip issues a random, 32-bit number to the battery chip, which combines that number with a longer, 64-bit "key," and bounces it back to the phone. If the new number doesn't match a similarly calculated number in the cell phone, the battery is rejected. Bad news for consumers, perhaps, but good news for manufacturers.

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