Also see OTPW:<p><a href="http://www.cl.cam.ac.uk/~mgk25/otpw.html" rel="nofollow">http://www.cl.cam.ac.uk/~mgk25/otpw.html</a><p>According to its author:<p><i>"OTPW is not compatible with and is not derived from either S/KEY or OPIE. It is a completely independent and different design, which I believe fulfils my functional and security requirements better."</i>