Example implementations described herein are directed to authentication based on the user's private factors, while not revealing at the server side information allowing the server (or anyone with the server's information) to deduce the private answers. In example implementations, the user answers a questionnaire with authentication factors, wherein the answers are transformed in a one-way fashion and the transformed answers are provided to the server side. Example implementations facilitate authentication based on polynomial interpolation or other methods to permit a user to authenticate, even if the user does not answer all of the questions correctly.