SDAP

Abstract

Hop-by-hop data aggregation is a very important technique for reducing the communication overhead and energy expenditure of sensor nodes during the process of data collection in a sensor network. However, because individual sensor readings are lost in the per-hop aggregation process, compromised nodes in the network may forge false values as the aggregation results of other nodes, tricking the base station into accepting spurious aggregation results. Here a fundamental challenge is how can the base station obtain a good approximation of the fusion result when a fraction of sensor nodes are compromised? To answer this challenge, we propose SDAP, a Secure Hop-by-hop Data Aggregation Protocol for sensor networks. SDAP is a general-purpose secure data aggregation protocol applicable to multiple aggregation functions. The design of SDAP is based on the principles of divide-and-conquer and commit-and-attest . First, SDAP uses a novel probabilistic grouping technique to dynamically partition the nodes in a tree topology into multiple logical groups (subtrees) of similar sizes. A commitment-based hop-by-hop aggregation is performed in each group to generate a group aggregate. The base station then identifies the suspicious groups based on the set of group aggregates. Finally, each group under suspect participates in an attestation process to prove the correctness of its group aggregate. The aggregate by the base station is calculated over all the group aggregates that are either normal or have passed the attestation procedure. Extensive analysis and simulations show that SDAP can achieve the level of efficiency close to an ordinary hop-by-hop aggregation protocol while providing high assurance on the trustworthiness of the aggregation result. Last, prototype implementation on top of TinyOS shows that our scheme is practical on current generation sensor nodes such as Mica2 motes.