Patent attributes
Techniques described herein may be used to implement a Completely Automated Public Turing test to tell Computers and Humans Apart (CAPTCHA) test that requires a user of a user device (e.g., a smartphone, a laptop computer, etc.) to physically move in a certain pattern. In one implementation, a user device may prompt the user to physically move the user device according to a specified pattern. As the user does so, sensors of the user device may detect the movements of the user, and cause the user to be authenticated based on the physical movements. In another implementation, a user device may request that the user make a physical gesture in front of the user device. In so doing, an infrared sensor of the user device may detect the user's movements, and the user device may cause the user to be authenticated based on the physical movements.