Among various others, the Grayhole and Blackhole
attacks are considered as the most dangerous attacks towards
adhoc network. Even though, there exist several mechanisms
for securing adhoc networks from such attacks, traditional
preventive approaches in this regard have serious limitations
and several disadvantages. Nodes share a single symmetric
key for encryption and decryption of messages. Also, there is
a problem of group re-keying which is complex and time
consuming task. Also AODV fails to remove malicious nodes
during the route discovery process and therefore does not
succeed to transfer all data packets to the destination under
Blackhole and Grayhole attacks. Most of the traditional
methods lack reliability. Also, under these attacks, the Packet
Delivery Ratio (PDR), Throughput, may decrease, as the
number of malicious nodes increases. So a new mechanism
for securing ad hoc networks has been proposed