Enter your PIN code securely!: utilization of personal difference of angle kappa

In previous studies, the angle kappa, the offset between the optical axis and visual axis, was considered to be calibrated when eye trackers based on a 3D model were used. However, we found that the angle kappa could be used as personal information, which is immeasurable from outside the human body. This paper proposes a concept for PIN entry by considering the characteristics of the angle kappa. Thus, we measured the distribution of the angle kappa and developed a prototype of the system. We demonstrated the effectiveness of the method.