An Efficient Mechanism for Securing Mobile Ad Hoc Networks Using Public Key Cryptography (PKC)

Security of networks depends on reliable key management systems which generate and distribute symmetrical/asymmetrical encryption/decryption keys between communicating parties. Traditionally, in wired networks, a central server is responsible to generate and distribute the keys securely. But because of no central server or fixed infrastructure exists in mobile ad hoc networks, there are many difficulties to carryout key management in dynamic and self organized mobile ad hoc networks. The dynamic change in topology results in the change of trust relationship among the nodes. In this paper, we have proposed a key management scheme in grouped network structure in which group leader of a group is randomly shifted, our scheme of key management doesn't require any trusted third party. The group leader is responsible to generate and distribute ids and public-private key pair to nodes. This method reduces the quantity of keys to distribute among the nodes. Using Public key cryptography (PKC) any of the two members of group can share a session key securely to communicate. INTRODUCTION The problem of efficiently and securely broadcasting to a remote cooperative group occurs in many newly emerging networks. A major challenge in devising such systems is to overcome the obstacles of the potentially limited communication from the group to the sender, the unavailability of a fully trusted key generation center, and the dynamics of the sender. The existing key management paradigms cannot deal with these challenges effectively. In this paper, we circumvent these obstacles and close this gap by proposing a novel key management paradigm. The new paradigm is a hybrid of traditional broadcast encryption and group key agreement. In such a system, each member maintains a single public/secret key pair. Upon seeing the public keys of the members, a remote sender can securely broadcast to any intended subgroup chosen in an ad hoc way. Following this model, we instantiate a scheme that is proven secure in the standard model. Even if all the non-intended members collude, they cannot extract any useful information from the transmitted messages. After the public group encryption key is extracted, both the computation overhead and the communication cost are independent of the group size. Furthermore, our scheme facilitates simple yet efficient member deletion/ addition and flexible rekeying strategies. Its strong security against collusion, its constant overhead, and its implementation friendliness without relying on a fully trusted authority render our protocol a very promising solution to many applications. A MANET is a special type of wireless network in which mobile hosts are connected by wireless interfaces forming a temporary network without any