ABSTRACT
This chapter discusses various attacks that most frequently occurs on any authentication schemes. It provides various remedies for those attacks. Device anonymity break can help the attacker to track the device if it is a mobile device or obtain the other information like type of device, use of device, frequency of device data collection, energy consumption by device and so on. Perfect forward secrecy is the mechanism that ensures that if the server is attacked and compromised then the entire system of communication will not be null and void. Off line password guessing attack is the most dangerous attack if an attacker is able to implement it within a polynomial time on the system. Most of the smart card based schemes provide protection from password guessing attack. There are other cyber attacks that also exist like side channel attack, stuxnet and many more.
