## 2 Related Work
ARAN provides security against external attacks by introducing authentication, message integrity and non-repudiation. Every node in ARAN has a certificate from a trusted server; therefore, it becomes difficult for malicious nodes to participate in the routing process. Processing in ARAN is divided into three stages: a preliminary certification process, a mandatory end-to-end authentication stage and an optional stage providing a secure shortest path. ARAN doesn't record the entire route information and also doesn't consider the total number of hops in the route discovery. As it makes use of public key cryptography to protect routing process, the time delay of signature generation and verification is significant. In general, significant time delay at each hop causes unacceptable route acquisition latency. [PERSON], [PERSON] and [PERSON] [13] have suggested a mechanism to counter the blackhole attack that could be initiated by the malicious node present in _ad hoc_ networks. In their proposed scheme, they have modified the RREP packet by adding an extra field that carries information about the one-hop next node. After the RouteReply packet is received from an intermediate node, a special RREQ is generated for the one-hop next node of the replying node. This is to ensure that the path conveyed by RREP exists from the intermediate node to the destination node or not. If the reply is sent by that node, the route is considered to be safe and free of blackhole nodes. While this scheme is successful in eliminating the blackhole attack by a single attacker, it fails completely in identifying a cooperative blackhole attack involving multiple malicious nodes or other forms of passive attacks. In [14], techniques based on symmetric encryption to protect the network from external attacks are used. All the nodes in the network have to obtain a one-time public and private key pair from a Certification Authority (CA), along with a CA key, which have to be used while exchanging the session keys by the communicating nodes. These session keys are used to encrypt both routing and data packets. Although this solution is capable of protecting the routing information and possible external attacks, maintaining a group secret for a one-hop neighbor all the time consumes a significant bandwidth. Even after using such a computationally heavy approach, it cannot counter the impersonating nodes because node authentication and data integrity are not guaranteed inside the group. In [15], a new secure routing protocol, AODV-SEC, was proposed. This protocol is based on AODV and considers the main features of SAODV. As per the proposal, a trusted CA issues digital certificates along with encryption keys. This digital certificate is a new type of certificate, known as m-Cert, and contains only relevant information related to the certificate. This, in turn, reduces the overhead by 50%. This m-Cert is X.509 standard compatible. With this approach, the path that is formed may not be the shortest. [PERSON], [PERSON] and [PERSON] [16] proposed Security Aware ad hoc Routing (SAR) protocol. This takes into consideration the trust level of intermediate nodes during the route formation phase. In most protocols, the length of the route is the only metric used. The required trust level is specified in the modified RREQ packets. When intermediate nodes receive an RREQ packet with a particular trust level, the node can only process the packet or forward it if it can provide the required trust level. However, limited security is achieved at the cost of performance degradation in terms of latency time and, in certain cases, the route formation even fails. The authors of [17,18] has raised a very critical aspect related to the research being done in the field of MANETs specially related to the use of simulation tools. In a survey [17], it was concluded that most of the research articles related this field used simulation for experimentation and random waypoint models was used by 64% of simulations.