Table 6 Experimental Computation times for various group sizes

Members (n)

Cluster members \(\left( {l\, = \,\left\lceil {\surd n} \right\rceil } \right)\)

Cluster size \(\left( {r\, = \,\left\lceil {{n \mathord{\left/ {\vphantom {n l}} \right. \kern-0pt} l}} \right\rceil } \right)\)

Setup time (ms)

Level-1 cluster key computation time (ms)

Level-2 computation time (ms)

Total group key generation time excluding setup time (ms)

Level-I

Level-II

Members

Cluster heads

Cluster heads as members

Group head