Authentication is the process of uniquely proving an identity to a certain service, network or device and the verification of the given identity. Upon successful identity verification, access to certain services, networks or devices are granted.
Authentication usually means that there is some way to ensure that the entity to which you are talking to is who it claims to be. This is called authentication of the channel end point. Usually you also need to authenticate yourself to the service in order for the service to be sure that you are you, not someone else who is pretending to be you. This is the authentication of the message originator. Authentication can be based on different kinds of methods. The most usual case is the use of a password, but it isn't really a good choice, because passwords are typically short and easy to break. The more secure methods include the use of public key cryptography, challenge-response schemes, symmetric encryption, etc. Authentication in general has several security requirements. These include protection against replay attacks, confidentiality, resistance against man-in-the-middle attacks etc. All of these are common to any authentication scheme to be used. More information about authentication methods and threats that they may have can be found in basic text books about computer security [4,32].
Types of Authentication
As mentioned there are principally two types of authentication and it is worth understanding the two types and determining which you really need to be doing. User Authentication is the process of determining that a user is who he/she claims to be. Entity authentication is the process of determining if an entity is who it claims to be. Imagine a scenario where an Internet bank authenticates a user initially (user authentication) and then manages sessions with session cookies (entity authentication). If the user now wishes to transfer a large sum of money to another account 2 hours after logging on, it may be reasonable to expect the system to re-authenticate the user!
A wireless ad hoc network is a decentralized wireless network. The network is ad hoc because it does not rely on a preexisting infrastructure, such as routers in wired networks or access points in managed (infrastructure) wireless networks. Instead, each node participates in routing by forwarding data for other nodes, and so the determination of which nodes forward data is made dynamically based on the network connectivity.