A non-transitory computer-readable medium encoded with a computer-readable program which, when executed by a first processor, will cause a computer to execute a method of authenticating a user, the method including training a plurality of models. The method additionally includes sending, by a computer, an acoustic signal. Further, the method includes receiving, by the computer, a reflected acoustic signal, wherein the reflected acoustic signal comprises information about a signature. Moreover, the method includes receiving, by the computer, motion data about the information about the signature. The method additionally includes comparing the information about the signature to a model to generate a score. Additionally, the method includes deciding, based on the score, if the information about the signature is within a predetermined tolerance level.