Motion Passwords

This paper introduces "Motion Passwords", a novel biometric authentication approach where virtual reality users verify their identity by physically writing a chosen word in the air with their hand controller. This method allows combining three layers of verification: knowledge-based password input, handwriting style analysis, and motion profile recognition. As a first step towards realizing this potential, we focus on verifying users based on their motion profiles. We conducted a data collection study with 48 participants, who performed over 3800 Motion Password signatures across two sessions. We assessed the effectiveness of feature-distance and similarity-learning methods for motion-based verification using the Motion Passwords as well as specific and uniform ball-throwing signatures used in previous works. In our results, the similarity-learning model was able to verify users with the same accuracy for both signature types. This demonstrates that Motion Passwords, even when applying only the motion-based verification layer, achieve reliability comparable to previous methods. This highlights the potential for Motion Passwords to become even more reliable with the addition of knowledge-based and handwriting style verification layers. Furthermore, we present a proof-of-concept Unity application demonstrating the registration and verification process with our pretrained similarity-learning model. We publish our code, the Motion Password dataset, the pretrained model, and our Unity prototype on https://github.com/cschell/MoPs