Aggregation Protocol for Sensor Networks

Hop-by-hop data aggregation is a very important technique for reducing the communication over5 head and energy expenditure of sensor nodes during the process of data collection in a sensor 6 network. However, because individual sensor readings are lost in the per-hop aggregation process, 7 compromised nodes in the network may forge false values as the aggregation results of other 8 nodes, tricking the base station into accepting spurious aggregation results. Here a fundamental 9 challenge is how can the base station obtain a good approximation of the fusion result when a 10 fraction of sensor nodes are compromised? 11 To answer this challenge, we propose SDAP, a Secure Hop-by-hop Data Aggregation Protocol 12 for sensor networks. SDAP is a general-purpose secure data aggregation protocol applicable to 13 multiple aggregation functions. The design of SDAP is based on the principles of divide-and14 conquer and commit-and-attest. First, SDAP uses a novel probabilistic grouping technique to 15 dynamically partition the nodes in a tree topology into multiple logical groups (subtrees) of similar 16 sizes. A commitment-based hop-by-hop aggregation is performed in each group to generate a 17 group aggregate. The base station then identifies the suspicious groups based on the set of group 18 aggregates. Finally, each group under suspect participates in an attestation process to prove the 19 correctness of its group aggregate. The aggregate by the base station is calculated over all the 20 group aggregates that are either normal or have passed the attestation procedure. Extensive 21 analysis and simulations show that SDAP can achieve the level of efficiency close to an ordinary 22 hop-by-hop aggregation protocol while providing high assurance on the trustworthiness of the 23 aggregation result. Last, prototype implementation on top of TinyOS shows that our scheme is 24 practical on current generation sensor nodes such as Mica2 motes. 25