Security in Wireless Ad Hoc and Sensor Networks

13

Specific Challenges and Solutions

In this chapter we explain other challenges specific to ad hoc and sensor networks. Instead of surveying all the solutions related to a specific challenge, one or two well-known schemes are elaborated for each challenge. Our goal is to introduce the specific challenges and their technical implications.

13.1 SPINS: Security Protocols for Sensor Networks

The first challenge is the stringent resource constraints, especially in wireless sensor networks. The hardware limitations for sensor networks are explained in Chapter 2. The memory available in a sensor node is typically in the order of Kbytes. Moreover, a sensor node has limited computational power and its lifetime is based on the lifetime of an onboard battery and therefore power consumption is always an important consideration. Finally, sensor nodes generally transmit short data packets, e.g. 30 bytes. This indicates that even a very low-cost security scheme may introduce high overhead, i.e. 3 bytes is 10% of a 30-byte packet.

All of these factors dictate the need for a very low cost security scheme. For example, asymmetric encryption schemes that require long signatures and overhead, e.g. 50–1000 bytes per packet, are impractical for sensor networks. Similarly, block ciphers, e.g. AES and DES, which require high computation codes or large look-up tables, may not be practical for sensor nodes. SPINS (Perrig et al., 2001b) is perhaps the earliest security protocol that addresses these challenges. ...