RC4 algorithm is one of the most significant stream and symmetric cryptographic algorithms, it is simple and used in various commercial products, it has many weaknesses such as a bias in the key stream that some key bytes are biased toward some values. In this paper, a new algorithm is proposed by using initial state factorial to solve the correlation issue between public known outputs of the internal state by using an additional state table with the same length as that of the state to contain the factorial of initial state elements. The analysis of RC4 and developed RC4 algorithm is done based on their single bias and double byte bias and shows that many keystream output bytes of RC4 are produced key stream bytes that are biased to many linear combinations while developed RC4 key bytes have no single and double biases. The results show that the series that is generated by developed RC4 is more random than that generated by RC4 and the developed algorithm is faster than RC4 execution time and requires less time. Additionally, the developed algorithm is robust against many attacks such as distinguishing attack.

Networks which function without having any centralized fixed infrastructure or central administration are called MANETs (Mobile Ad hoc Networks). These networks are formed by small or large set of mobile nodes and communicate through the wireless links. Such Networks requires best routing protocols to establish error-free and efficient communication links. MANETs has the property of dynamically changing topology due to their mobile nodes, which move from one place to another. Overall performance of MANET routing protocols depends upon various network and protocol parameters. Mobile ad hoc networks have the characteristics of self-forming and self-healing. The routing algorithms of the routing protocols ensure selection of routes and connectivity between the mobile nodes. This paper presents analysis of three well known routing protocols of MANETs, namely; AODV (Ad hoc On Demand Distance Vector), DSDV (Destination Sequenced Distance Vector) and OLSR (Optimized Link State Routing). Analyses of these routing protocols have been carried out using NS-3 (Network Simulator-3) by varying node density and node pause time. Different performance metrics such as throughput, packet delivery ratio, end to end delay, packet loss and normalized routing load have been considered for this analysis. This analysis concludes better performance of the OLSR routing protocol.

Digital images have become part of everyday life by demonstrating its usability in a variety of fields from education to space research. Confidentiality and security of digital images have grown significantly with increasing trend of information interchange over the public channel. Cryptography can be used as a successful technique to prevent image data from unauthorized access. Keeping the nature of image data in mind, several encryption techniques are presented specifically for digital images, in literature during past few years. These cryptographic algorithms lack a benchmark for evaluation of their performance, cryptographic security and quality analysis of recovered images. In this study, we have designed and developed a benchmark based on all the parameters necessary for a good image encryption scheme. Extensive studies have been made to categories all the parameters used by different researchers to evaluate their algorithms and an optimum benchmark for evaluation is formulated. This benchmark is used to evaluate three image encryption schemes. The results of evaluation have highlighted the specific application areas for these image encryption schemes.

The energy has undergone a major concern in wireless sensor networks. One direction of the LEACH protocol would be towards a future in which four levels will continue to dominate. The other direction would be towards to improve these levels further and increasingly smaller amount of energy consumption. The support provided by the LEACH protocol has been crucial in which upgrade these levels and build smart distributed network. The previous scenario is not motivated by the scientific altruism. They are large number of clients in the proposed scenario and therefore have a good reason to encourage a scalable alternative for communication. LEACH protocol to take a leaf out of the proposed scenario and it has a good energy saver, less energy consumption. The proposed scenario needs to be better understanding the catalytic role played by the previous three levels LEACH protocol. It should also see whether there is scope for deploying more nodes through collaboratively proposed protocol with three level protocols.

Underwater Wireless Sensor Networks (UWSNs) consist of certain number of sensors and vehicles interacting with each other to collect data. In recent years, the use of Autonomous Underwater Vehicle (AUV) has improved the data delivery ratio and maximized the energy efficiency in UWSNs. Clustering is one of the effective techniques in energy management which increases the lifetime of these networks. One of the most important parameters in creating optimized clusters is the choice of appropriate cluster head (CH), which not only increases the lifetime of the network and the received data in the sink, but also reduces energy consumption. Clustering of networks was primary done via distributed methods in previous researches. It spends too much energy and also involves too many nodes in the clustering process and fades their main functionality, which is gathering data in sensor networks. It also causes more damping of the network. However, in the proposed protocol, instead of having them distributed by the network and the nodes, the stages of clustering and selecting the appropriate CH is the task of the AUV (Autonomous Underwater Vehicle). Since all the necessary measures to cluster in the network will be carried out by the AUV by this method, many control overheads in the process of clustering the network will be removed and energy consumption caused by nodes reduces significantly. With this method, the network scalability will also be manageable and under control. For simulating and implementing our method we mainly used the OPNET software. The results show that energy consumption of nodes in the proposed algorithm has been significantly improved compared to previous results.

Need of wireless communication is increasing to work from distance. That is why new applications are made everyday which increases demand of spectrum but due to limitation of spectrum and inefficient utilization of spectrum. A new paradigm is constituted which is called Cognitive Radio Network (CRN). It get more attention in recent times due to most promising solution for the efficient utilization of spectrum. Spectrum sensing in CRN makes it prone to many attacks on each layer. One of these attacks is PUE attack where a malicious user pretends to be a primary user and not let others to use primary user's channel in its absence. It may cause Denial of Service attack in the network. There are many techniques available in the literature for detection and prevention of PUE attack but still there are some limitations in these approaches. Current research provides detection results based on the energy level of all users in the network. In this paper we provide a novel approach to prevent PUE attacker based on signal activity patterns. Simulation is done in MATLAB-2013 and results show that proposed method gives excellent performance.

Delay/disruption Tolerant Networks (DTNs) provide connectivity in those networks which lack continuous connectivity or considerable delays like that of terrestrial mobile networks, military ad-hoc networks, sensor or planned network in space. They lack in an end-to-end path between Source and Destination resulting in long variable propagation delays. The Internet Protocols do not operate properly in these networks, thus raising a variety of new challenging problems in this area. The DTN effectively improves the network communications where the connectivity in the network is intermittent or is prone to disruptions. Routing in DTNs is challenging because of long and frequent time durations of non-connectivity. There are several routing approaches that have been proposed with strategies ranging from flooding to forwarding approaches. In this paper these protocols are analyzed based on the quantitative data gathered by simulating each protocol in ONE simulator environment. The performance is discussed and compared for different routing protocols and results are discussed for different performance metrics.

Energy efficiency is a very crucial issue for battery operated Wireless Sensor Networks (WSNs). Routing plays a major in energy dissipation and it is shown in the literature that Cluster based approach is the most energy effective in any network in comparison to direct or multi hop based approach. Therefore, optimized Clustering became a key point to achieve energy efficiency in Wireless Sensor networks. In this paper, we have designed and implemented a novel protocol in MATLAB in which Cluster Heads are chosen on the basis of energy threshold, minimum average distance from surrounding nodes and farthest distance among Cluster Heads to provide optimal coverage. This paper also compare results of randomly selected CHs and farthest CHs and results demonstrates that farthest chosen CHs provide much better results than randomly selected CHs. To further evaluate performance of our protocol, results of our protocol are compared with LEACH and proposed protocol dominates LEACH in terms of minimizing transmission distance, energy dissipation and hence increasing network lifetime. Apart from this, proposed protocol is based on Poisson distribution because simulation results clearly states that Poisson distribution is very well suited for WSN in comparison to Uniform and Random distribution.