This paper describes a new protocol for authentication in ad-hoc networks. The protocol has been designed to meet specialized requirements of ad-hoc networks, such as lack of direct communication between nodes or requirements for revocable anonymity. At the same time, a ad-hoc authentication protocol must be resistant to spoofing, eavesdropping and playback, and man-in-the-middle attacks. The article analyzes existing authentication methods based on the Public Key Infrastructure, and finds that they have several drawbacks in ad-hoc networks. Therefore, a new authentication protocol, basing on established cryptographic primitives (Merkle's puzzles and zero-knowledge proofs) is proposed. The protocol is studied for a model ad-hoc chat application that provides private conversations.
A mobile ad hoc network consists of mobile nodes that can move freely in an open environment. Communicating nodes in a wireless and mobile ad hoc network usually seek the help of other intermediate nodes to establish communication channels. In such an open environment, malicious intermediate nodes can be a threat to the security and or anonymity of the exchanged data between the mobile nodes. While data encryption can protect the content exchanged between nodes, routing information may reveal valuable information about end users and their relationships. The main purposes of this paper are to study the possibility of achieving anonymity in ad hoc networks, and propose an anonymous routing protocol, similar to onion routing concept used in wired networks. Our protocol includes a mechanism to establish a trust among mobile nodes while avoiding untrustworthy nodes during the route discovery process. The major objective of our protocol is to allow only trustworthy intermediate nodes to participate in the routing protocol without jeopardizing the anonymity of the communicating nodes. We present our scheme, and report on its performance using an extensive set of simulation set of experiments using ns-2 simulator. Our results indicate clearly that anonymity can be achieved in mobile ad hoc networks, and the additional overhead of our scheme to DSR is reasonably low when compared to a non-secure DSR ad hoc routing protocol.