Design and analysis of a wireless authentication protocol against DoS attacks based on Hash function

Denial of service(DoS) by exhausting the server resources has become a major security threat in open networks.Particularly,wireless networks are vulnerable to DoS attacks when they have much fewer system resources than the wired counterparts.The basic strategy against DoS attacks is to impose an adjustable cost on the attackers while the attacks are being launched.An authentication protocol against DoS attacks that is improved by asking the client to commit its system resources to the execution of the protocol before the server allocates its memory and processing time.The server sends the client a puzzle whose solution requires a brute force search for some bits of the inverse of an one way Hash function.The difficulty of the puzzle is parameterized according to the server available resources.The server stores the protocol state and computes expensive public key operations only after it has verified the client's solution.The puzzle protects the server that authenticates the clients against resource exhaustion attacks during the first messages of the connection opening before the clients are reliably authenticated.Then a four pass public key authentication and key establishment protocol is proposed.