AES Hardware-Software Co-Design in WSN

Carlos Tadeo Ortega Otero, Jonathan Tse, and Rajit Manohar

Wireless Sensor Networks (WSNs) present a challenging design space for encryption algorithms. We evaluate hardware, software, and hybrid implementations, including one of our own design, of Advanced Encryption Standard (AES) encryption engines in the context of WSN microcontrollers. We examine the tradeoffs between energy, throughput, memory footprint, and sensor network node lifetime. Our measured results and models show that our fully Quasi Delay-Insensitive, asynchronous AES design, combined with a low-power microcontroller, offers a 60x increase in throughput at 90x less energy per bit over the commercially available TI MSP430 AES WSN hardware. Our hardware AES offers a 30x throughput improvement over its software counterpart, albeit with reduced lifetime. By incorporating power gating and providing dedicated memory resources to the AES engine, hybrid implementations can provide a 6x better throughput and increase the lifetime by 10% over software.