A Mobile Ad hoc Network (MANET) is a self governing network of mobile nodes connected through wireless links. Mobile ad hoc networks (MANET) are infrastructure less networks, dynamically formed by an autonomous system of mobile nodes that are connected via wireless links. Each node in MANET operates not only as a host but also as a router that has the task to forward data. Mobile nodes only can communicate directly via wireless link if they are within each other’s radio range otherwise, they depends on intermediate nodes to forward packets. The success of communication highly depends upon the cooperation of other nodes.
In MANET, data delivery is a major challenge. Due to unpredicted movement of mobile nodes topology of the network changes frequently. The primary goal of any routing protocol is establishing an optimal and efficient route between the communicating nodes. the past few years, much research efforts have been focused on this area and many different kinds of routing protocols have been put forward in the literature, such as Wireless Routing Protocol (WRP), Dynamic Source Routing protocol (DSR), Ad hoc On Demand Distance Vector protocol (AODV) and Location Aided Routing. However, from the beginning of its design, almost none of the routing protocols specify security measures.
To implement Security in MANETs is a complex issue. Nodes in the network are much more vulnerable to attacks compare to wired (traditional) networks due to the open medium, dynamically changing network topology, lack of centralized monitoring and management point, and lack of a clear line of defense. These factors have changed the battle field situations for the ad hoc wireless networks against the security threats. The ad hoc wireless networks the nodes communicate with each other on the basis of mutual trust without any a centralized administration. These characteristic makes ad hoc wireless networks more vulnerable to be exploited by an attacker inside the network. Wireless links also makes the ad hoc wireless networks more susceptible to attacks, which make it easier for the attacker to go inside the network and get access to the ongoing communication.

The word steganography comes from the Greek word Steganos, which mean covered or secret and graphy means writing or drawing. Therefore, steganography means, literally, covered writing. Steganography is the art and science of hiding information such that its presence cannot be detected and a communication is happening. Secret information is encoded in a manner such that the very existence of the information is concealed. Paired with existing communication methods, steganography can be used to carry out hidden exchanges. The main goal of steganography is to communicate securely in a completely undetectable manner and to avoid drawing suspicion to the transmission of a hidden data It is not to keep others from knowing the hidden information, but it is to keep others from thinking that the information even exists. The main goal or steganography is to communicate securely in a completely undetectable manner and to avoid drawing suspicion to the transmission of a hidden data]. During the process, characteristics of these methods are to change in the structure and features so as not to images, videos, sound files, and other computer files that contain perceptually irrelevant or redundant information can be used as “covers” or carriers to hide secret messages. After embedding a secret message into the cover-image, a so-called stego-image is obtained. The basic model of steganography consists of Carrier, Message, Embedding algorithm and Stego key. The model for steganography is shown in Figure 1. Carrier is also known as a cover-object, which embeds the message and serves to hide its presence.
Steganography Concept:
Although steganography is an ancient subject, the modern formulation of it is often given in terms of the prisoner’s problem proposed by Simmons, where two inmates wish to communicate in secret to hatch an escape plan. All of their communication passes through a warden who will throw them in solitary confinement should she suspect any covert communication. The warden, who is free to examine all communication exchanged between the inmates, can either be passive or active. A passive warden simply examines the communication to try and determine if it potentially contains secret information. If she suspects a communication to contain hidden information, a passive warden takes note of the detected covert communication, reports this to some outside party and lets the message through without blocking it. An active warden, on the other hand, will try to alter the communication with the suspected hidden information deliberately, in order to remove the information.