The In today’s era with increase in the use of internet and networking devices, there is an increase in demand for more secure data communication. This problem has led to development of hybrid security mechanisms. Various techniques are available in literature that makes use of different steganography and cryptographic mechanisms which has certain pros and cons. In this paper, we propose a new hybrid security mechanism that tries to choose the best cryptographic and steganography mechanism. In addition, to increase the embedding capacity of the proposed mechanism, Huffman encoding scheme is used. The proposed strategy is implemented in MATLAB-09. In order to check the efficacy of the proposed technique three types of analysis were performed named as: security, robustness and efficiency analysis. It is found from the simulation and results that the proposed scheme outperforms other techniques in literature in every aspect.

The scarcity of free spectrum compels us to look for alternatives for ever increasing wireless applications. Cognitive Radios (CR) is one such alternative that can solve this problem. The network nodes having CR capability is termed as Cognitive Radio Network (CRN). To have communication in CRN a routing protocol is required. The primary goal of which is to provide a route from source to destination. Various routing protocols have been proposed and tested in idealistic environment using simulation software such as NS-2 and QualNet. This paper is an effort in the same direction but the efficacy is evaluated in realistic conditions by designing a simulator in MATLAB-7. To make the network scenario realistic obstacles of different shapes, type, sizes and numbers have been introduced. In addition to that the shape of the periphery is also varied to find the impact of it on routing protocols. From the results it is observed that the outcomes in the realistic and idealistic vary significantly. The reason for the same has also been discussed in this paper.

Mobile Ad hoc Network (MANET) consists of wireless mobile nodes that can be set up any time at any place without the requirement of pre-requisite infrastructure. The nodes in these networks have several constraints such as battery power, processing capability and bandwidth. Moreover each node in MANET has to act as a relay node for others for the successful network operations. In an ideal environment in spite of above mentioned limitations, the node performs this community task faithfully but as in real world there exists nodes with selfish attitude also. Therefore, this paper is an effort to evaluate the efficacy of network with nodes having such behavior prevailing in realistic environment. Various researchers have evaluated the network performance in idealistic conditions but none has made an effort to evaluate it in practical condition such as in presence of obstacles. To make the scenario realistic different number, type and shape of obstacles were taken. The work was accomplished by designing a simulator in MATLAB-11.

A routing protocol is used to facilitate communication in ad hoc network. The primary goal of such a routing protocol is to provide an efficient and reliable path between a pair of nodes. The routing protocols for ad hoc network can be categorized into three categories: table driven, on demand and hybrid routing. The table driven and hybrid routing strategies require periodic exchange of hello messages between nodes of the ad hoc network and thus have high processing and bandwidth requirements. On the other hand on demand routing strategy creates routes when required and hence is very much suitable for ad hoc network. This paper therefore examines the performance of three on demand routing protocols at application layer using QualNet-5.01 simulator.

Mobile Ad hoc Network (MANET) is a self-organized wireless network, consisting of nodes (mobile devices) responsible for its creation, operation and maintenance. The communication in the MANET is of multihop in nature due to absence of any fixed infrastructure. An attacker may intrude easily into MANET by posing as legitimate intermediate node and present various types of security attacks on data exchanges taking place between source and destination. In this paper we study the impact of presence of black hole node on MANET performance on the basis of reachability, hop count, neighbor node density and path optimality. We observe that as the percentage of black hole nodes increases, the MANET performance degrades significantly.

Communication in Mobile Ad Hoc Network (MANET) is accomplished using routing protocols. These protocols provide an efficient and reliable path for data sharing. In static environment where the nodes are stationary these protocols performs exceptionally well but in an environment having mobile nodes the performance of these protocols degrade drastically. To investigate this factor various researchers developed mobility models using simulation tools such as QUALNET, NS-2 etc. These models represent the erratic movement of nodes and give us an idea regarding their location, velocity and acceleration change over time. This paper is an effort to study the effect of mobility models such as Random Way Point, File and Group Mobility Models on the performance of routing protocols using QUALNET simulator. The results show that the choice of mobility models affect the performance of routing protocol significantly.

In order to facilitate communication in Mobile Ad hoc Network (MANET), routing protocols are developed. The performance of these protocols depends upon various factors such as: transmission range, number of nodes deployed and mobility of the nodes. Another factor which affects the performance of MANET routing protocols is the environment in which ad hoc network is deployed. The MANET environment may contain obstacles such as mountains lakes, buildings and river. These obstacles restrict nodes movement but may or may not obstruct the effective transmission range of nodes deployed. This paper is an effort to evaluate the performance of MANET routing protocols in presence of obstacles by designing a simulator in MATLAB-10. To make the situation more realistic obstacle of different shapes, size, number and type were introduced in the simulation region. We found significant impact of the same on the performance of routing protocols.

Steganalysis is the art of detecting the message's existence and blockading the covert communication. Various steganography techniques have been proposed in literature. The Least Significant Bit (LSB) steganography is one such technique in which least significant bit of the image is replaced with data bit. As this method is vulnerable to steganalysis so as to make it more secure we encrypt the raw data before embedding it in the image. Though the encryption process increases the time complexity, but at the same time provides higher security also. This paper uses two popular techniques Rivest, Shamir, Adleman (RSA) algorithm and Diffie Hellman algorithm to encrypt the data. The result shows that the use of encryption in Steganalysis does not affect the time complexity if Diffie Hellman algorithm is used in stead of RSA algorithm.