Data hiding techniques can be employed to enhance the security of biometrics-based authentication systems. In our previous work, we proposed a method to hide challenge responses in a WSQ-compressed fingerprint image. In this paper, we extend the work to analyze the security holes in the data hiding method and enhance the hiding technique to thwart attacks on the system. We employ several proven IT security techniques to provide a secure method of hiding responses in fingerprint images. The technique presented here can be used in hiding responses in other biometrics with minor changes to suit the domain.