Energy comparison of AES and SHA-1 for ubiquitous computing

Abstract

Wireless sensor networks and Radio Frequency Identifiers are becoming mainstream applications of ubiquitous computing. They are slowly being integrated into our infrastructure and therefore must incorporate a certain level of security. However, both applications are severely resource constrained. Energy scavenger powered sensor nodes and current RFID tags provide only 20 pW to 50 pW of power to the digital component of their circuits. This makes complex cryptography a luxury. In this paper we present a novel ultra-low power SHA-1 design and an energy efficient ultra-low power AES design. Both consume less than 30 pW of power and can therefore be used to provide the basic: security services of encryption and authentication. Furthermore, we analyze their energy consumption based on the TinySec protocol and come to the somewhat surprising result, that SHA-1 based authentication and encryption is more energy efficient than using AES for payload sizes of 17 bytes or larger. © IFIP International Federation for Information Processing 2006.