Security for portable devices with low power authentication chip

Paul Boughton
To protect mobile-phones, cameras, portable power tools, and other battery-powered applications, Atmel has launched a low-cost, cryptographic battery authentication chip.

The AT88SA100S CrytpoAuthentication IC is the only battery authentication chip that uses a cryptographic engine and a 256-bit key that cannot be cracked using brute force methods and is used to protect portable devices from counterfeit battery packs.

The AT88SA100S ensures replacement batteries meet the product manufacturer’s standards by providing secure, reliable authentication that can be used to prevent product operation and/or charging with counterfeit product.

The AT88SA100S has 256-bits of SRAM for key storage, a guaranteed unique 48-bit serial number stored permanently inside the chip and 88 one-time, user-programmable fuses that can be used for the storage of battery parameters or status information. The 256-bit key is stored in the on-chip SRAM at the battery manufacturer’s site and is powered by the battery pack itself. Physical attacks to retrieve the key are very difficult to effect because removing the CryptoAuthentication chip from the battery erases the SRAM memory, rendering the chip useless.

Battery authentication is based on a 'challenge/response' protocol between the microcontroller in the portable end-product (host) and the CrytpoAuthentication IC in the battery (client). In order to speed system design, Atmel provides complete source code libraries for ARM and AVR microcontrollers that implement all necessary cryptographic modules for performing the host-side authentication capability. The AT88SA100S requires only a single GPIO pin on the host processor and only three wires on the connector to the battery, plus a standard bypass capacitor for a low overall BOM impact. 

The AT88SA100S battery authentication IC is available now in production quantities in a 1.3mm x 3mm, green-compliant (exceeds RoHS) 3-pin SOT-23 package at $0.65 in quantities of 1K units, making it 40% to 60% less expensive than any other battery-authentication IC on the market.

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