To defend against compromised member nodes injecting bogus raw readings, clusterhead nodes aggregate the collected data using the secure sort-group-filter (SSGF) aggregation algorithm proposed in this paper, which will be presented in detail in the following subsection.
One transmission for the aggregation result is looked as one round (i.e., each round consists of both SSGF and TDMA-based listening defense mechanism).
According to the SSGF, affected by node w, the d; sent by a normal node i may also be deemed as abnormal data if [d.sub.i] [member of] [[d.sub.(k)], [d.sup.(l)])[union]([d.sub.(h)], [d.sub.(*)]].
We present the simulation results of SSGF, including the detection ratio, false positive ratio, the accuracy of aggregation results, the communication overhead for monitoring, and aggregation results for a slow poisoning attack.
Additional information on SSGF
, including an on-line application, may be found at the website maintained by the Krell Institute who administers the program for DOE: