[Retracted] HGKM: An Efficient Hybrid Group Key Management for Unmanned Autonomous Vehicles MBN in Wireless Network Environment

Table 6

The computation cost of join operation to group members.

Group key management algorithm	Joining leader element		Joining member element
	Members directly affected operation unit	Members outside immediately attacked operation unit	Members directly affected operation unit	Members outside immediately attacked operation unit
HGKM		1		1
LKH	H
OFT	H

h_unit: the tallest from key tree to activity component in HGKM. h: the highest of that gathering key tree, which measures up to 2 log n; n is the aggregate number of gathering individuals.