Comparing Block Cipher Modes of Operation on MICAz Sensor Nodes

Wireless sensor networks are a key technology for "ubiquitous computing" applications. The challenges of securing such networks are tremendous. On the one side, sensor nodes are commonly deployed in potentially hostile environments, which requires additional protection in comparison to traditional computing systems. On the other side, the capabilities of sensor nodes in terms of computing power, memory, and available energy are severely limited, which makes it hard to adapt existing security solutions. In this paper, we examine different options for providing confidentiality and message authentication to sensor network communication. More specifically, we examine four modern block cipher modes of operation regarding their applicability in sensor networks. These are the offset codebook mode (OCB), the counter cipher feedback with header mode (CCFB+H), the EAX mode, and the Galois/Counter mode (GCM). Our practical evaluation targets the MICAz sensor node and accounts for the typically small packet size of sensor network traffic. Our results indicate that the CCFB+H mode is the best choice for a large range of applications.