Maintaining Privacy and Integrity of Range Queries in Wireless Sensor Networks

The Two-tiered sensor network model has been widely adopted because of its storage and energy saving benefits, where storage node serves as an intermediate tier between sensors and sink for storing and processing queries. Storage node may contain vital data; we should recognize that they are vulnerable to attack. Therefore, we assume that storage nodes are not trustworthy but the sink is completely trustworthy. Here we propose SafeQ, protocols that prevents attackers from gaining information from both sensor collected data and sink issued queries. A SafeQ uses a novel technique to encode both data and queries such that a storage node can correctly process encoded queries over encoded data without knowing their values to privacy. We have two schemes to preserve integrity, they are-one using Merkle hash trees and another using a new data structure called neighborhood chains to generate integrity verification information so that sink can verify whether the result of the query contains exactly the data items that satisfy the query. For improving performance, we have an optimization technique using bloom filters to reduce the communication cost between sensors and storage nodes.