1. A method comprising: receiving private data, the private data (1) comprising private time-sensitive data associated with activities of a user, and (2) being stored in a computer system; generating an alphanumeric word using the private data; prompting the user to speak the alpha-numeric word; extracting a voice feature from a received phrase in response to the prompting; comparing, via a processor, the voice feature with a voice profile, to yield a comparison; and determining whether to accept a speaker identity based on the comparison.