  Because of lack of infrastructure and Central Authority(CA), secure
communication is a challenging job in MANETs. A lightweight security solution
is needed in MANET to balance its nodes resource tightness and mobility
feature. The role of CA should be decentralized in MANET because the network is
managed by the nodes themselves without any fixed infrastructure and
centralized authority. In this paper, we created a distributed Public Key
Infrastructure (PKI) using Shamir secret sharing mechanism which allows the
nodes of the MANET to have a share of its private key. The traditional PKI
protocols require centralized authority and heavy computing power to manage
public and private keys, thus making them not suitable for MANETs. To establish
a secure communication for the MANET nodes, we proposed a lightweight crypto
protocol which requires limited resources, making it suitable for MANETs.
