The bq26100 device provides a method to authenticate battery packs, ensuring that only packs manufactured by authorized sub-contractors are used in the end application. The security is achieved using the SHA-1 hash function inside the widely adopted keyed-hash message authentication code (HMAC) construction. A unique 128-bit key is stored in each bq26100 device, allowing the host to authenticate each pack. The bq26100 device communicates to the system over a simple one-wire bi-directional serial interface. The 5-kbits/s SDQ bus interface reduces communications overhead in the external microcontroller. The bq26100 device also derives power over the SDQ bus line via an external capacitor.