Optimizing AES for Embedded Devices and Wireless Sensor Networks

Abstract—The increased need for security in embedded ap-plications in recent years has prompted efforts to develop en-cryption/decryption algorithms capable of running on resource-constrained systems. The inclusion of the Advanced Encryption Standard (AES) in the IEEE 802.15.4 Zigbee protocol has driven its widespread use in current embedded platforms. We propose an implementation of AES in a high-level language (C in this case) that is the first software-based solution for 16-bit microcontrollers capable of matching the communication rate of 250 kbps specified by the Zigbee protocol, while also minimizing RAM and ROM usage. We discuss a series of optimizations and their effects that lead to our final implementation achieving an encryption speed of 286 kbps, RAM usage of 260 bytes, and code size of 5160 bytes on the Texas Instruments MSP430 microprocessor. We also develop rigorous benchmark experiments to compare other AES implementations on a common platform, and show that our implementation outperforms the best available implementation by 85%. Index Terms—AES, encryption, embedded optimizations, se-cure sensor networks, CC2420, MSP430, Zigbee security. I