18-06-2013, 12:14 PM
SECURITY IN AD-HOC WIRELESS NETWORKS
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ABSTRACT
Security is a major concern in the design of modern communication systems. It is articularly challenging with wireless networks such as Ad hoc networks. Ad hoc networks are dynamically reconfigured. For this reason they are vulnerable to several major security threats. This paper focus on different theoretical aspects of security services, attacks and security mechanisms.
INTRODUCTION
Ad hoc networks [5,15] do not have a fixed network topology. Nodes are mobile and can communicate with each other while in range, but otherwise are disconnected. This node mobility causes frequent changes of the network topology, and possible portioning. Ad hoc networks can be used to model several wireless applications, such as military operations in which the nodes are military units (soldiers, tanks and other vehicles, planets etc).equipped with wireless communication devices and more generally wireless communication system in which the fixed network is restricted. The restructuring of such networks is usually due to their mobility; however, it can also be caused by the enemy .the enemy can destroy captured devices try to use them to gather information or undermine the operations. The traditional model for static networks with Byzantine faults [7] may be used to describe some of the security threats of ad hoc networks, but what characterizes ad hoc networks is that their structure changes continuously. Furthermore, the tools which are used to establish the security (authentication, confidentiality, integrity, availability and non repudiation) of traditional networks cannot in general be easily adapted for the requirements of ad hoc networks, particularly when these get partitioned. Such issues must be addressed in order to secure ad hoc networks.
Availability
Availability implies that requested services (e.g. Bandwidth and connectivity) are available in a timely manner even though there is a potential problem in the system. Availability of a network can be tempered for example by dropping off packets and by resource depletion attacks.
Confidentiality
Confidentiality ensures that classified information in the network is never disclosed to unauthorized entities. Confidentiality can be achieved by using different Encryption techniques so that only the legitimate communicative nodes can analyze and understand the transmission. The content disclosure attack reveals the contents of the message being transmitted and physical information about a particular node respectively.
Authenticity
Authenticity is a network service to determine a user's identity. Without Authentication, an attacker can impersonate any node, and in this way one by one node, it can gain control over the entire network.
Integrity
Integrity guarantees that information passed on between nodes has not been tempered in the transmission. Data can be altered both intentionally and accidentally. (for example through hardware glitches, or in case of ad hoc wireless connection through interferences)
EXISTING SECURITY SOLUTIONS
Traditional mechanisms, such as asymmetric cryptography, one way hash functions and other techniques implanting authentication, confidentiality, integrity and non-repudiation can be used whether in a wired or wireless network. On the other hand, access control, which for us stands for fire walling, seems somehow more difficult to enforce in ad hoc network.
On other hand, applicative fire walling, as achieved by proxies, cannot be considered in Manets because of their centralized nature. According to the security goals to be achieved, several mechanisms can be implemented on different network layers. Most existing mechanisms are based on cryptography and certification must be implemented to secure key exchanges.This point is particularly important in an environment prone to "Man in the Middle attacks"such as manets. A certification mechanism can be implemented in many ways ranging from a simple physical exchange of keys ,to a more sophisticated PKI based exchange .The choice depends on the configuration of the network and the required security.
SECURITY MECHANISM IN ADHOC WIRELESS NETWORKS
Message encryption and digital signatures are two important mechanisms for data integrity and authentication. There are two types of data encryption mechanisms. Symmetric and Asymmetric (or public key) echanisms.Symmetric cryptosystems use the same key (the secret key) for encryption and decryption of a message, and asymmetric cryptosystems use one key (the public key) to encrypt a message and another key (the private key)to decrypt it. Public and private keys are related in such a way that only the public key can be used to encrypt message and only the corresponding private key can be used for decryption purpose. Even if attacker comprises a public key, it is virtually impossible to deduce the private key.
CONCLUSION
In this paper, we have analyzed the security threats an ad hoc network faces and presented the security objectives that need to be
achieved. On one hand, the security-sensitive applications of ad hoc networks require high degree of security, on other hand ,ad hoc networks are inherently vulnerable to security attacks.Therefore, security mechanisms are indispensable for ad hoc networks. The idiosyncrasy of ad hoc networks poses both challenges and opportunities for these mechanisms.