A comparison of secure data aggregation schemes for wireless sensor networks

Several secure data aggregation (SDA) schemes are proposed in literature to reduce energy consumption for cryptographic operations and minimize their impact on the sensor network lifetime. Comparisons of SDA schemes focus primarily on the number of cryptographic operations used and number of bits transmitted in a given scenario. In reality, however, a sensor node operation is more complex: significant frame level overhead compared to data payload, sporadic communication, unreliable wireless links owing to radio interference from environment and competing transmissions by other sensor nodes, non-negligible energy consumption during sleep or power down mode, and overhead due to clock drift compensation. In this paper, we evaluate two representative SDA schemes in a more realistic setting by taking these other issues into account. We used TOSSIM simulator for our analyses, but validate our implementation of data aggregation techniques and simulation results using an analytical model. Our results show that, it is more crucial to reduce the number of packets transmitted than the overall number of bits transmitted. With low duty cycles and low probability of sensor data generation, even simple concatenation of sensor data, which reduces mostly the number of packets transmitted, is nearly as effective as the more sophisticated SDA schemes; when sensor data are generated more frequently, SDA schemes that do not require intermediate nodes to decrypt sensor data give 10% higher network lifetime.