1. A method for authenticating a speaker, the method comprising: receiving reference speech input comprising a reference passphrase to form a reference recording; determining a reference set of feature vectors for the reference recording, the reference set of feature vectors having a time dimension; receiving test speech input comprising a test passphrase to form a test recording; determining a test set of feature vectors for the test recording, the test set of feature vectors having the time dimension; correlating the reference set of feature vectors with the test set of feature vectors over the time dimension; comparing the reference set of feature vectors to the test set of feature vectors to determine whether the test passphrase matches the reference passphrase; determining a reference fundamental frequency of the reference recording, wherein determining the reference fundamental frequency comprises determining a voice feature of the reference recording as a function of a time period T; determining a test fundamental frequency of the test recording, wherein determining the test fundamental frequency comprises determining a voice feature of the test recording as a function of the time period T; comparing the reference fundamental frequency to the test fundamental frequency to determine whether a speaker of the test speech input matches a speaker of the reference speech input; and authenticating the speaker of the test speech input in response to determining that the reference passphrase matches the test passphrase and that the speaker of the test speech input matches the speaker of the reference speech input; wherein the reference set of feature vectors comprises Mel Cepstrum feature vectors, and wherein the test set of feature vectors comprises Mel Cepstrum feature vectors.