Measurement of Energy Costs of Security in Wireless Sensor Nodes

Both correct transmission using hashing and protection of messages using encryption in sensor nodes require additional energy. This paper describes our measurement results for energy consumption in CrossBow and Ember sensor nodes for the process of exchanging data messages between nodes both in the clear and in a protected form. Full strength algorithms were loaded into and executed in nodes. It was found that the CPU operates for substantially longer times for both hashing and encryption operations compared to the time for handling messages without any security. The longer radio transmission times due to hashing were especially costly. Hence, security algorithms have great impacts on energy consumption in sensor nodes. For the full operational mode, with CPU processing and also radio transmission of messages, our results indicate that the lifetime of a transmitting node in a security regime is only about one-half of the lifetime without security.