The main problem with user authentication on the Web is that many sites are used infrequently and people forget their passwords over time. Another problem is that the number of sites which require a username and password combination to access it are increasing dramatically. The result is that users choose trivial passwords or they pick the same password that they already use for higher-security applications. Even so, users often forget their passwords; that's why many sites have forgotten-password recovery systems in place.
Déjà Vu is well suited for this problem because the ``forgotten-password'' recovery rate is very high for Random Art images, as we show in the user study. The creation of image portfolios is also easy to accomplish over the web.