Graphical passwords: a survey <s> Guessing <s> In this paper we propose and evaluate new graphical password schemes that exploit features of graphical input displays to achieve better security than text-based passwords. Graphical input devices enable the user to decouple the position of inputs from the temporal order in which those inputs occur, and we show that this decoupling can be used to generate password schemes with substantially larger (memorable) password spaces. In order to evaluate the security of one of our schemes, we devise a novel way to capture a subset of the "memorable" passwords that, we believe, is itself a contribution. In this work we are primarily motivated by devices such as personal digital assistants (PDAs) that offer graphical input capabilities via a stylus, and we describe our prototype implementation of one of our password schemes on such a PDA, namely the Palm PilotTM. <s> BIB001 </s> Graphical passwords: a survey <s> Guessing <s> Graphical password schemes have been proposed as an alternative to text passwords in applications that support graphics and mouse or stylus entry. In this paper we detail what is, to our knowledge, the largest published empirical evaluation of the effects of user choice on the security of graphical password schemes. We show that permitting user selection of passwords in two graphical password schemes, one based directly on an existing commercial product, can yield passwords with entropy far below the theoretical optimum and, in some cases, that are highly correlated with the race or gender of the user. For one scheme, this effect is so dramatic so as to render the scheme insecure. A conclusion of our work is that graphical password schemes of the type we study may generally require a different posture toward password selection than text passwords, where selection by the user remains the norm today. <s> BIB002 </s> Graphical passwords: a survey <s> Guessing <s> In ubiquitous textual password schemes, users choose passwords that contain predictable characteristics that are roughly equated with what users flnd easy to recall. This motivates us to examine user choice in graphical passwords to determine whether predictable characteristics exist that may reduce the entropy of the password space. We present an informal user study of the scheme proposed by Jermyn et al. (1999), and the results, both in context of the study’s goals and a separate analysis of the results performed at a later date. Our results support that user drawings contain the predictable characteristics relating to symmetry, number of composite strokes, and centering within the grid. Our results also highlight a usability challenge with the DAS scheme. <s> BIB003
Unfortunately, it seems that graphical passwords are often predictable, a serious problem typically associated with text-based passwords. For example, studies on the Passface technique have shown that people often choose weak and predictable graphical passwords BIB002 . Nali and Thorpe's study BIB003 revealed similar predictability among the graphical passwords created with the DAS technique BIB001 . More research efforts are needed to understand the nature of graphical passwords created by real world users.