Performance and Energy Consumption Analysis of AES in Wireless Sensor Networks

With WSN deployments increasing in popularity, securing those deployments becomes a necessity. This can be achieved by encrypting inter-node communications and/or using message authentication codes. AES is a well studied symmetric cipher, with no known practical vulnerabilities, that can be used to solve both problems. We provide an optimized implementation of AES, with five modes of operation for encryption (ECB, CBC, CFB, CTR and GCM) and two modes for authentication (CBC-MAC and GCM-MAC), that use the hardware accelerator available on the ATmega128RFA1 microcontroller, and compare it with the best known software implementation. We show that our hardware AES implementation is both faster and more energy efficient than a software implementation. This is not the case for previous sensor nodes and implementations, which show an improved execution speed, but with a higher energy consumption. We also show that our implementation of CTR is faster and more energy efficient than the unsecure fully hardware- supported ECB mode.