Techniques for identifying a user and authenticating payment transactions based on the identification include requesting the user to send his audio, video, and/or image from the point of sale location and comparing the received audio, video, and/or image to an audio/video/image on file to identify and authenticate the user as being the official holder of the payment device being used in the transaction. Once the user is authenticated, the payment processing can be performed using conventional techniques. Some techniques involve use of accelerometer data associated with the user in addition to or in lieu of the audio, video, and/or image data to perform the identification and authentication of the user.