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Attacks on Graphical Password: A Study on Defense Mechanisms and Limitations

User authentication is mostly reliant on password-based based verification. Users generally used text-based passwords, which are user-friendly but often predictable and vulnerable to some common attacks. To overcome these shortcomings, graphical authentication methods have emerged. Here, users choose a sequence of images as passwords. Though such methods help users to better remember their passwords, they too suffer from attacks seen in the case of textual passwords. This paper presents a comprehensive summary of the vulnerabilities state of the art graphical password schemes against the following well-known attacks -  Dictionary, Guessing, Brute force, Shoulder surfing, Spyware, and Social engineering. We believe the findings of this study can help researchers design more secure graphical password schemes making them more usable and a realistic replacement for text-based passwords. 
 