Pass-image authentication method tolerant to random and video-recording attacks

User authentication is widely used in many Internet services and is also used by automatic teller machines (ATMs). Recently, there has been an increase in the ATM password thefts using small charge-coupled device cameras. This study discusses a user authentication method in which graphical passwords, instead of alphanumeric ones as, are used to mitigate observation attacks. Several techniques for password authentication have been discussed in various studies. However, there has not been sufficient research on authentication methods that use pass-images instead of pass-texts. This study proposes a user authentication method that is tolerant to serious attacks when a user's pass-image selection operation is video recorded twice. In addition, usage guidelines recommending eight pass-images are proposed, and the corresponding security strength is evaluated.