3.5 Re-keying Technique Among the chosen sj N , some nodes has to be designated as initiators, which initiates the re-keying process. In this section, suppose that initiators are selected by centralized node considering reputation index (RI) of nodes. The initiators are selected based on the RI of nodes (explained in section 3.1.3). The direct reputation of node sj N is given as: ) 1(ReRe z prpwspws
Where reputation prpws Re value of sj N contained in wi N prior to the addition of recent satisfaction index. z = constant that replicates the level of confidence possessed by wi N for its sj N . wsP = recent satisfaction index for wi N about sj N Thus sj N with high pws Re values are selected as initiators. The selected initiator starts the re-keying process periodically using the re-keying interval int .int RkyRky is the fixed parameter and rekeying procedure is demonstrated as follows. Let int Rky is the initial time Let max Rky represent the maximum thresholds for re-keying interval. Let min Rky indicates the minimum thresholds for re-keying interval. Let Rkyt represent the stop time.
Fig.5 Re-keying time interval
According to the re-keying interval, re-keying process is performed using the following cases.
Case 1 If int Rky > minRky Then The re-keying is performed for requested weak nodes from NT by the initiator. End if Case 2 If int Rky > maxRky Then The re-keying is performed for requested strong nodes from NT by the initiator. End if