Top-k Query Processing and Malicious Node Identification against Data Replacement Attack in MANETs

In mobile ad hoc networks (MANETs), it is effective for mobile nodes to retrieve data items using top-k queries, in which data items are ordered according to a particular attribute score, and the query-issuing node acquires the data items with the k highest scores. However, accurate results may not be acquired in environments where malicious nodes are present. In top-k queries, it is important to neutralize attacks in which malicious nodes attempt to replace necessary data items with unnecessary ones (we call these, data replacement attacks). In this paper, we propose methods for top-k query processing and malicious node identification against data replacement attack in MANETs. In the top-k query processing method, in order to maintain accuracy of the query result, nodes reply with data items with the k highest scores, along multiple routes. Moreover, to enable detection of data replacement attacks, reply messages include information on the route along which reply messages are forwarded, and thus the query-issuing node can know the data items that properly belong to the message. In the malicious node identification method, the query-issuing node first narrows down the malicious node candidates, using the received message information, and then requests information on the data items sent by these candidates. In this way, the query-issuing node can identify the malicious node. Finally, we verify, through simulation experiments, that the proposed top-k query processing method achieves high accuracy of the query result, and that the malicious node identification method effectively identifies a malicious node.