1. An electronic-device-implemented method for authenticating a user, the method comprising: providing an authentication instruction to move the electronic device in a pre-defined manner; using an imaging sensor in the electronic device, capturing multiple images of the user while the user moves the electronic device in the pre-defined manner; using a displacement sensor in the electronic device, determining positions of the electronic device when the multiple images were captured; comparing the images at the positions with corresponding pre-existing images of the user captured at different points of view; and if the comparisons achieve a match condition, authenticating the user.