In MANET multicasting, forward and backward secrecy result in increased
packet drop rate owing to mobility. Frequent re-keying cause large message
overhead which increases energy consumption and end-to-end delay.
Particularly, the prevailing group key management techniques cause frequent
mobility and disconnections. So there is a need to design a multicast key
management technique to overcome these problems. In this paper, we propose
the mobility based key management technique for multicast security in
MANET. Initially the nodes are categorized according to their stability index
which is estimated based on the link availability and mobility. A multicast tree
is constructed such that for every weak node, there is a strong parent node. A
session key-based encryption technique is utilized to transmit a multicast data.
The re-keying process is performed periodically by the initiator node. The rekeying
interval is fixed depending on the node category so that this technique
greatly minimizes the re-keying overhead. By simulation results, we show that
our proposed approach reduces the packet drop rate and improves the data
confidentiality.