Date Added: Jul 2012
First phase for information security is authentication and the main phase for authentication is memorability of password and rules that will be used for authentication purpose. The most commonly used scheme is textual scheme. However the strong password of textual scheme is hard to memorize and normal passwords are vulnerable to many attacks. Hence, graphical authentication scheme has been proposed as an alternative solution, motivated particularly by the fact that humans can remember images better than text. However, these are vulnerable to shoulder surfing attack. To overcome this problem many grid based authentication schemes has been proposed. But, either these scheme's shoulder surfing resistant property is not strong or these have many complex rules, which are hard to memorize.