1. A method for identifying a user of a handheld device comprising the steps of: detecting, using a motion sensor and a processor, a hand tremor associated with a user holding said handheld device; and identifying said user based on said detected hand tremor, wherein said step of identifying further comprises: (a) obtaining tremor data sets associated with a plurality of users; (b) extracting features from each of said tremor data sets to generate an extracted feature set for each of said plurality of users, (c) removing features from each of said extracted feature sets to generate a reduced feature set for each of said plurality of users, (d) identifying clusters associated with said reduced feature sets, and (e) identifying said user by generating new feature vectors based on said hand tremor data and determining whether said new features lie within said clusters, wherein said step (b) of extracting features further comprises: calculating a plurality of point Fast Fourier Transforms (FFTs) averaged with an overlap for a number of points in said movement data within a predetermined frequency range.