Date Added: Nov 2012
In two-tier wireless sensor networks, resource-rich storage nodes at the upper tier collect sensing data from resource poor sensor nodes at the low tier, and then answer queries from the user. Sensor nodes perform sensing task and submit sensing data in one time-slot to the nearest storage node while storage nodes answer and process the query from the network owner. However the storage nodes confront serious security concerns. Storage nodes may be compromised and leak the sensitive data as well as returning fake query result. Therefore, it is important to protect the privacy and verify the query results.