20-08-2012, 12:28 PM
Adhoc Network using NS-3 and Implemented Simple Data Encryption Standard
Adhoc Network.doc (Size: 2.72 MB / Downloads: 80)
ABSTRACT
"Ad Hoc" is actually a Latin phrase that means "for this purpose." It is often used to describe solutions that are developed on-the-fly for a specific purpose. In computer networking, an ad hoc network refers to a network connection established for a single session and does not require a router or a wireless base station.”
If you need to transfer a file to your friend's laptop, you might create an ad hoc network between your computer and his laptop to transfer the file. This may be done using an Ethernet crossover cable, or the computers' wireless cards to communicate with each other. If you need to share files with more than one computer, you could set up a multi-hop ad hoc network, which can transfer data over multiple nodes.
Basically, an ad hoc network is a temporary network connection created for a specific purpose (such as transferring data from one computer to another). If the network is set up for a longer period of time, it is just a plain old local area network (LAN). An identity-based broadcast encryption protocol for ad hoc networks is proposed. Whenever a new mobile ad hoc network is formed, the proposed protocol only requires each group member to broadcast his/her identity to construct the group key, which avoids a large number of message exchanges between group members like group key management protocols proposed previously. Hence it is highly efficient in terms of member removal to construct a new network. In addition, our protocol is also efficient in computation since the encryption and the decryption only require two bilinear pair computations.
INTRODUCTION
Wireless network technology enables computing devices to communicate with each other without any physical medium. Compared with wired networks, wireless communication provides better connectivity and mobility, which allows mobile devices to access other local area networks or the Internet at anytime and anywhere. The benefits of flexible routing, global connectivity and a highly adaptive potential make ad-hoc networks suitable for a wide range of applications in both military and commercial environments, such as battlefields, disaster relief operations, mobile device/personal networking, mobile information sharing and vehicular networks . However, maintaining security in wireless ad-hoc networks is quite challenging.
First, unlike wired networks that at least have some degree of physical protection, wireless communication over radio waves lacks defined and restricted boundaries. Anyone can connect to the network as long as the transmitted signal strength is strong enough to cover the area, and therefore, security attacks on data communication, such as passive eavesdropping, packet injection or even violations of confidentiality are widespread.
Second, the end-to-end communication in network cannot rely on any fixed infrastructure, such as a base station or access points (AP); thus, existing security protocols that are based on a centralized or infrastructure-based network environment will not work in this environment.
ROUTING
Routing is generally accomplished by maintaining a routing table in each end system and router that gives, for each possible destination network, the next router to which the internet datagram should be sent. The routing table may be static or dynamic. A static table, however, could contain alternate routes if a router is unavailable. A dynamic table is more flexible in responding to both error and congestion conditions. In the Internet, for example, when a router goes down, all of its neighbors will send out a status report, allowing other routers and stations to update their routing tables. A similar scheme can be used to control congestion; this is a particularly important function because of the mismatch in capacity between local and wide-area networks. Routing tables may also be used to support other internetworking services, such as those governing security and priority. For example, individual networks might be classified to handle data up to a given security classification. The routing mechanism must assure that data of a given security level are not allowed to pass through networks not cleared to handle such data. Another routing technique is source routing. The source station specifies the route by including a sequential list of routers in the datagram. This, again, could be useful for security or priority requirements. Finally, we mention a service related to routing: route recording. To record a route, each router appends its internet address to a list of addresses in the datagram. This feature is useful for testing and debugging purposes.
RADIO SIGNAL STRENGTH (RSS)
Radio signal strength (RSS) is notorious for being a noisy signal that is difficult to use for ranging-based localization. In this study, we demonstrate that RSS can be used to localize a multi-hop sensor network, and we quantify the effects of various environmental factors on the resulting localization error. Ranging-based localization is the task of identifying the positions of a network of nodes based on estimates of the distances between them, called range estimates. In many ways, radio signal strength (RSS) is an ideal modality for range estimation in wireless networks because RSS information can be obtained at no additional cost with each radio message sent and received. The simplicity of RSS is especially appealing for the localization in wireless sensor networks because of their cost, size, and power constraints, despite the fact that RSS may yield very noisy range estimates.
A main challenge with RSS ranging is that the effect of reflecting and attenuating objects in the environment
can have much larger effects on RSS than distance, making it difficult to infer distance from RSS without a detailed model of the physical environment. This has given RSS the reputation of being too “unpredictable”
for range estimation [9, 29].
It is often assumed, however, that RSS can be used for range estimation in open, outdoor environments
that are free from obstructions such as walls and trees.
RSS-based ranging systems are much more sensitive to environmental factors than expected, even in an “ideal” open, outdoor environment. Changing some environmental factors such as transmission power does not only mean that calibration coefficients must change, but that the radio signal carries fundamentally less distance information and that localization will suffer. This high sensitivity may limit the practical use of RSS for
ranging-based localization, even in ideal outdoor environments, unless the system is designed to automatically
adjust factors such as transmission power and calibration coefficients.
CONCLUSION
• In this project presented we presented simulation of simple wireless adhoc network using NS-3 and implemented Simple Data Encryption Standard (SDES) RSA algorithm in C++ for Encryption and decryption.
• It fulfills the need for security protection in ad hoc networks. Our protocol ensures the privacy of communication and protects sensitive data by dynamically changing the secret key for data encryption during packet transmission. Under this protocol, only the original sender and authorized recipient are able to decrypt the cipher text, which is accomplished through a secret key available only to them.
• Encryption in ad-hoc networks is used to protect data in transit, for example data being transferred via networks (e.g. the Internet, e-commerce), mobile telephones, wireless microphones, wireless intercom systems, Bluetooth devices and bank automatic teller machines.
• A series of experiments in different network configurations has been simulated in NS-3, and the results also indicate the efficiency of our proposed protocol, as well as the low computational overhead during end-to-end communication. “ns-3” is a discrete-event network simulator for Internet systems, targeted primarily for research and educational use. ns-3 is free software, licensed under the GNU GPLv2 license, and is publicly available for research, development, and use.