Are graphical authentication mechanisms as strong as passwords?

The fact that users struggle to keep up with all their (textual) passwords is no secret. Thus, one could argue that the textual password needs to be replaced. One alternative is graphical authentication. A wide range of graphical mechanisms have been proposed in the research literature. Yet, the industry has not embraced these alternatives. We use nowadays (textual) passwords several times a day to mediate access to protected resources and to ensure that accountability is facilitated. Consequently, the main aspect of interest to decision-makers is the strength of an authentication mechanism to resist intrusion attempts. Yet, researchers proposing alternative mechanisms have primarily focused on the users' need for superior usability while the strength of the mechanisms often remains unknown to the decision makers. In this paper we describe a range of graphical authentication mechanisms and consider how much strength they exhibit, in comparison to the textual password. As basic criteria for this comparison, we use the standard guessability, observability and recordability metrics proposed by De Angeli et al. in 2005. The intention of this paper is to provide a better understanding of the potential for graphical mechanisms to be equal to, or superior to, the password in terms of meeting its most basic requirement namely resisting intrusion attempts.